Lotus Laser Systems

How Materials React to a Laser

There are generally three ways that a material can react to a laser: Engrave, mark or cut.

Laser engraving is defined when material ablation (removal) occurs. In this case the laser engraving machine will vaporise some of the material to create some depth.

Some materials can only be laser engraved, such as wood for example. In other words, the material cannot be exposed to the laser without some ablation occurring, however, in this example ablation is desirable because the perceived quality and value of laser engraved wood is further enhanced when there is a significant degree of ablation.

Some materials work well with minimal ablation but react adversely when over-exposed to the laser. Cast acrylic is a good example in this case where some ablation by a 10.6µm laser creates a beautifully lustrous effect but when over-exposed the engraving can become very powdery and tainted by an adverse reaction to an excessive degree of thermal stress.

Laser marking constitutes the majority of laser applications and is where the material reacts without ablation to show a contrast between the area exposed to the laser and the area that has not been exposed to the laser. Laser marking is usually some form of colour change but can also include a reaction called ‘foaming’. Foaming is a material specific phenomenon that occurs when the laser marking machine heats the material to release gasses that raise and then solidify above the surface of the material.

Polycarbonate is a good example of a plastic that if exposed to a 1µm laser will colour change and foam with a highly contrasting and desirable effect.

Laser marking without ablation can provide for an incredibly detailed result, at super-high speeds and with zero to minimal adverse reactions from the base material.

Some materials can be laser marked or laser engraved according to the system configuration used and the laser parameters set. For example, a CO2 laser at the 10.6µm wavelength can only mark the surface of anodised aluminium. Increasing the intensity of the exposure can cause removal of the anodised surface but this is not very noticeable. Using a solid state laser, like a fiber laser at the 1µm wavelength, the same material can be surface marked or ablated to a considerable depth.

Laser cutting occurs when the laser vaporises the entire thickness of the material to create a void from upper to lower surface.

Solid, flat sheet materials are used for the vast majority of laser cutting where highly accurate and detailed cuts can be made by the laser that are impossible to produce by other forms of cutting technology.

For example, laser cut acrylic provides for an instantly polished edge and some textiles, such as silk for example, are heat-sealed by laser cutter where they may otherwise fray.

For some applications a finely controlled cut takes place by the laser. For example, ‘kiss-cutting’ of adhesive labels where the adhesive surface is laser cut but the backing material is not and also, the laser scoring of some materials to form a line that can form a break point, for example for snapping-off labels out of a sheet format.

At Lotus Laser Systems we manufacture a wide range laser marking and engraving solutions ideally configured for laser cutting, laser marking and laser engraving all types of materials. Our experts would be happy to recommend which configuration best suits your application.

Source: http://lotuslaser.blogspot.com/2016/04/how-materials-react-to-laser.html

Cooling of a DC Glass CO2 Laser

DC excited (glass) CO2 lasers at the 10.6µm wavelength are rapidly growing in popularity and fast overtaking the number of RF (metal) lasers sold, especially in the more price conscious markets such as laser cutting machines for schools and laser engravers for hobbyists.

Compared to an RF alternative, DC lasers have limited functionality, lower performance and a much shorter working life but they do offer the possibility of owning a laser cutter to some that would otherwise never be able to afford a laser cutting machine with an RF laser source.

All lasers require cooling and these days modern RF lasers are all cooled by air. DC lasers, however, are a less efficient technology and generate more heat as a by-product of the process so all DC laser need to be water-cooled.

Cooling the laser effectively and efficiently is a critical process. Failure to do so will cause massive fluctuations in the performance and reliability of the laser cutter, significantly shorten the working life of the laser itself and can in some cases lead to a premature, catastrophic laser failure.

Some very low cost machines ship with no more than what is an aquarium pump for the cooling device. Such devices are wholly inadequate as they do no more than to recirculate increasingly hotter water around the laser tube, some with variable rates of flow and pressure too.

For the laser to be cooled efficiently and effectively the coolant (water) must pass through a device specifically designed to control its temperature. In a laser cutting machine this device is called a chiller, although this can be a bit of a misleading description because the chiller will only actually reduce the coolant temperature after it reaches a set-point. It is therefore an ‘on-demand’ device, continually monitoring and keeping the coolant temperature constant.

Most chillers will use deionised water for the coolant, which helps to keep both the coolant and the internal workings of the laser clean. No matter what the coolant type the chiller must be regularly monitored and maintained to ensure that it is performing correctly.

Periodically, the chiller should be drained, the internal workings of the laser flushed and the chiller replaced with new coolant. Care should be taken to ensure that any air filters/vents on the chiller are also regularly cleaned/replaced. DC lasers are a consumable part. When replacing the laser the user should never use a chiller containing old coolant

The chiller should not be placed above the height of the laser. Ideally, it should be placed on a stable surface approximately 500mm from the floor and away from all other electrical devices. This minimises the likelihood of contamination of the cooling veins.

Pay careful attention not to allow the workplace to fall below 0c as this will cause the coolant to freeze and the chiller and the laser to become damaged.

Most DC lasers <100w work best when operated at a set temperature of 21c. If the laser cutting machine is within an environment that has a high temperature and/or relative humidity the operating temperature of the chiller should be set with 10c of the dew point, otherwise, condensation may form on the internal workings of the laser and the chiller causing a short. At maximum the chiller should not operate above 24c.

Maintaining an effective cooling device for your laser can save you significant time/money and prolong the life of your laser cutter.

At Lotus Laser Systems we manufacture a wide range laser marking and engraving solutions ideally configured for laser cutting and laser engraving all types of materials. Our experts would be happy to recommend which configuration best suits your application.

Source: http://lotuslaser.blogspot.com/2016/04/cooling-of-dc-glass-co2-laser.html

Hatch Settings for Laser Engraving

To simulate a solid (usually black) effect within artwork a laser engraving machine will follow a series of parallel lines to ‘fill in’ the solid area in a way similar to what you would shade between outlines on paper with a pencil.

For a plotter format laser engraving machine this software parameter is called ‘DPI’ or ‘resolution’ and for a galvo laser engraving machine it is called ‘Hatch’. For the purpose of this article we’ll call this parameter ‘hatch’.

With a plotter laser the options for adjusting the hatch parameters are very limited. All plotter lasers are constraint to engrave (raster) at one angle, this being zero degrees (left to right) so all plotter lasers only allow for one hatch variable, which is the distance that can be set for the spacing between the hatch lines selected from a list of approximately 6 or so predefined spacing. For example, 1000dpi, 600dpi, 333dpi and so on.

A better designed plotter laser engraver and all galvo laser engravers will allow for the hatch spacing to be set as a unit of measurement, usually down to increments as small as 0.01mm. This provides for a wider range of engraving effects as well as more flexibility to balance the job speed with the output effect and quality of the laser engraving.

Galvo lasers offer the very widest range of hatch parameters because all galvo laser engraving machines can hatch at any angle (a full 360 degrees) and most will have additional controls for the start/stop of the hatch line and also how the laser is control as the motion controls turns out of one hatch line and enters into the next.

The biggest influence on output effect is the hatch spacing and hatch angle. For some jobs a smaller distance between hatch lines will not only increase the resolution of the engraving but it will also influence how the material reacts with the laser. For example, smaller values for hatch spacing can produce on some materials, such as laser engraving stainless steel, a darker effect but add significantly to the process time.

Conversely, a low hatch density (larger hatch spacing) will not only provide for a much faster, lower resolution mark but on some materials it will cause a completely different effect, such as for example a silver effect on stainless steel.

When setting the hatch values it’s also important to consider the material type as well as the characteristics of the lens being used because these factors also determine the maximum achievable resolution.

If using a galvo laser engraving machine, experiment with multiple hatch angles that overlap each other. For some materials this will not only help to darken and deepen the laser engraving but it will also help to make the effect much smoother too.

At Lotus Laser Systems we manufacture a wide range laser marking and engraving solutions ideally configured for laser cutting and laser engraving all types of materials. Our experts would be happy to recommend which configuration best suits your application.

Source: http://lotuslaser.blogspot.com/2016/04/hatch-settings-for-laser-engraving.html

Laser Cutting and Laser Engraving Leather

Leather is a general term predominantly used to describe some form of hide (skin) that can be natural (of animal origin) or synthetic (man-made). If at all possible, when laser engraving or laser cutting leather try to use synthetic materials. Not only is this morally responsible but often the job is easier to achieve with a more predictable result due to the consistent nature of a man-made product compared to a natural animal hide.

There are a multitude of different colours, thickness and types of leather. Leather can be plain in finish, embossed with patterns or even retaining fur or hair.

When laser cutting or laser engraving leather the best laser wavelength to use is a CO2 laser at 10.6µm.

When laser engraving leather the best effects are produced by using lighter colours, such as tan or even better results can be achieved using colour dyed leathers where the contrast can be further enhanced.

One of the main obstacles to overcome is the adverse reaction that leather can have to the heat of the laser engraver, particularly when laser marking over larger areas. One way to overcome this is to pre-soak the leather before it is placed within the laser engraving machine. CAUTION: do not place wet materials inside the laser machine! Prior to attempting this technique seek detailed advice from our support department.

When pre-soaked the excess moisture within the material acts as a heat-sink to minimise the material warping and/or excessively charring during the laser cutting and laser engraving process. The retained moisture also adds weight to the leather, which minimises it from moving as air flow across it from the laser fume extraction unit.

After laser engraving, some types of leather can be further enhanced by rubbing hand cream or sun lotion onto the material to moisturise it and provide for a luxurious looking lustre, especially where it has been intensely laser engraved.

If using leather with hair, such as cowhide for example, some visually stunning effects can be produced by setting the parameters of the laser engraving machine to remove the hair but without marking the hide beneath. The results can be very eye-catching, similar to some hairstyles supported by basketball players! One examples of this technique is use the hide associated with one type of animal but etch it with a fur pattern associated with another type of animal.

Commercial applications for laser cutting and laser engraving leather range from decorative marking and branding of wallets, purses and handbags to cutting intricate patterns for shoes or even the creation of decorative hides to be used in manufacturing footstools.

At Lotus Laser Systems we manufacture a wide range laser marking and engraving solutions ideally configured for laser cutting and laser engraving all types of materials. Our experts would be happy to recommend which configuration best suits your application.

Source:- http://lotuslaser.blogspot.com/2016/04/laser-cutting-and-laser-engraving.html

Nucleation of Beer Glasses by Laser Engraving

Nucleation is a process whereby the inner surface of a drinking glass is marked to provide for a roughness to which the gasses from carbonated drinks, such as beer, will be attracted and released into the liquid at an accelerated rate.

There are several ways to mark glass like this but none come anywhere near to being as fast, effective, clean or low in cost to produce as a CO2 laser marking machine.

Compared to a standard glass, after the drink is poured, a nucleated glass will enhance the visual appearance of the liquid by making it look ‘fizzier’ and in particular with lager beers it increases the volume of the frothy head, characteristics that are highly desirable to both the seller and the consumer.

When comparing a nucleated glass to one that is not nucleated the difference in effect of the appearance after pouring can be massive. By comparison, the non-nucleated glass will show a liquid that looks very flat.

To reach into the bottom of a pint glass requires a significant degree of clearance from the lens of the laser engraving machine. There is also the speed of the laser marking to consider too. Therefore, the only viable system configuration for this process is a galvo delivered CO2 laser engraving machine at the 10.6µm laser wavelength.

Not much laser power is required for nucleation. A 45w laser is usually sufficient.

A typical nucleation mark by a galvo laser engraver will be produced in approximately 1 second. Therefore, when combined with well designed automation for handling the glasses it is possible to laser engrave well in excess of 3,000 glasses per hour with a single laser engraving machine.

As no material is vaporised during this process there is no requirement for fume extraction; somewhat of an exception compared to most other applications where aCO2 laser engraver is used.

As with all laser engraved glass, it is very important to balance the laser parameters well so as to create enough of a mark to work well and look good but not too much so that the glass engraving starts to fracture and splinter. Once the machine parameters are perfected this type of system will work reliably and consistently 24/7 with near to zero required maintenance.

Compared to conventional glass marking processes, another major advantage of laser engraving glass is the ease with which the content can be changed. It is in fact quite possible to create marks that are individual from one glass to the next without any user intervention.

At Lotus Laser Systems we manufacture a wide range laser marking and engraving solutions ideally configured for laser cutting and laser engraving all types of materials. Our experts would be happy to recommend which configuration best suits your application.

Source:- http://lotuslaser.blogspot.com/2016/04/nucleation-of-beer-glasses-by-laser.html

Laser Engraving Stone

Laser engraved stone can have a stunning visual impact, especially laser engraving photos to granite.

Not all forms of stone will laser engrave so careful selection of the material is important. Stone is a general term that can be used to describe two distinct materials:

1. Naturally occurring stone, mined from the ground and shaped by breaking, sawing, cutting, grinding and polishing. Examples would be granite, marble or slate.
2. Man-made stones, also known as synthetic, composite or engineered stone such as alabaster, quartz and a range of trade names the most famous of which is Corian. These composites contain a blend of natural stone materials encapsulated by bonding resins such as acrylic. Composite materials are available in a wider range of finishes, more consistent in their make-up and are much easier to machine into shapes.

Each different type of stone will laser engrave with differing degrees of effect. Most natural materials will not vaporize. Laser engraving granite, for example, produces a result that is very similar to laser engraving glass where the highly polished surface fractures when pulsed by the laser with little to no depth.

Softer materials such as some types of marble and most of the composites will to a varying extent vaporise with some depth. This can be beneficial if, for example, it is desired to paint-fill the laser engraving to enhance the visual impact.

Materials that are dark in colour and more uniform in their make-up produce the best results. For example, some of the best effects that we have seen have been to carefully selected, black marble or granite that shows minimal flecks or veins in the material. If the stone has too much character this can irregularities in the mark and interfere with the image too.

Also important is the selection of the laser wavelength. For the majority of laser engraving to stone a CO2 laser at the 10.6µm is used. This type of laser is required especially when laser engraving composites with depth.

However, some materials such as slate, for example, can be marked with amazing detail using a fiber laser at the 1µm wavelength. This type of laser produces a focal point that can be x10 smaller than a CO2 laser and so the resolution can therefore be x10 higher.

Flatness of the material is important too, especially for stone that is Riven such as slate, for example. Too much variation in height will cause the laser to defocus and produce and undesirable result.

Last but not least, it’s important to note that stone is a very heavy material. With most machines there are limitations with regard to the weight of the material that can be loaded to the worktable. In such cases a workaround can be to use thinner stone tiles that after laser engraving can be mounted to a larger stone backing.

Some laser engraving machines exist that are specifically designed for use by monumental masons. These types of machine generally use a gantry mounted laser to move the laser over the stone. This type of machine is very limited in scope and is generally not well suited to a wider range of laser engraving applications.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions ideally configured for laser cutting and laser engraving all types of materials. Our experts would be happy to recommend which configuration best suits your application.

Source - http://lotuslaser.blogspot.com/2016/04/laser-engraving-stone.html

Laser Cutting Wood

Insofar as laser cutting is concerned, wood can be separated into two distinct groups:

1. Natural timber from various species of tree. For example, maple or cherry wood.
2. Man-made wood manufactured by bonding wood pulp, fibers or shavings. For example, MDF or plywood

All natural timbers can be cut by a CO2 laser at the 10.6µm wavelength. Limitations only apply with regard to thickness and the degree of charring that is acceptable to the customer.

Special versions of laser cutting machine are made for specific wood cutting applications such as, for example, laser cutting plywood for label dies. However, for the purpose of this article we are referring to a typical benchtop format laser cutter <100w.

For most industries laser cutting anything beyond 12mm natural timber and 9mm plywood produces an undesirable result because the feed rate (speed of cut) combined with optical limitations causes the wood to adversely burn.

When laser cutting wood the rate of laser fume extraction, particularly underside extraction and air assist delivered through the nosecone, can never be too much. When vaporised, wood produces a very dense fume that if not immediately evacuated from the cutting line will rise into the path of the beam and absorb laser power, significantly dropping the feed rate of the cut and in turn accelerating the degree of charring at the edge of the cut.

High amounts of debris from laser cutting wood can also contaminate laser optics causing them to fail prematurely and also cause HAZ (Heat Affected Zone), which is an undesirable staining to the edge and surfaces of the material.

In machines where the design of extraction is poor, surface HAZ can be minimised by first applying a low-tack, paper based tape to both surfaces of the wood. The tape acts as a masking barrier, attracting the contamination. After laser cutting the paper is removed and the wood surface underneath is clean.

Natural timber has a tendency to warp, which is challenging for laser cutting as this causes the beam to defocus, producing undesirable results. Therefore, if the application calls for laser cutting of natural timber it is best to process the material as soon as possible after receiving it from the mill.

Man-made or engineered woods can contain resins that are actually designed to be fire retardant. This is unhelpful when trying to burn through the wood with a laser cutter! Therefore, if the application calls for using a form of engineered wood it’s wise to be very selective about the exact type of material you use. For example, plywood is most commonly available in a WBP or exterior grade. The resins used to bond this type of plywood are among the least laser friendly and will resist thelaser cutting process, accelerating HAZ.

Interior grade plywood, sometimes called white glue plywood, is among the most laser friendly plywood’s. Not as commonly available as exterior grade, interior grade should be used as a preference for laser cutting if the job specification allows it as the resins in the material will vaporise much cleaner.

An often overlooked aspect is that of the surface finish of wood prior to laser cutting. If the part to be laser cut is the finished item then the surface should always be sealed/finished before it is laser cut. This reduces HAZ and any HAZ present can be wiped off with a slightly damp cloth. If however the material is to be post processed, such as sanding for example, then pre-sealing the wood is not absolutely necessary as the HAZ will be removed during post processing.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions ideally configured for laser cutting and laser engraving wood. Our experts would be happy to recommend which configuration best suits your application.

Source:- http://lotuslaser.blogspot.com/2016/04/laser-cutting-wood.html

Laser Engraving Photos To Wood

Many owners of a laser engraving machine will tell you that laser engraving wood has to be the best looking effect that a laser engraving machine can produce.

This is especially true for laser engraving a photo to wood where the grain of the material can have a significantly enhancing effect on the image itself.

All natural timbers and most engineered wooden boards can be laser engraved by a CO2 laser at the 10.6µm wavelength but some natural timbers will not mark with contrast. Therefore, when selecting timber for photo laser engraving it’s wise to consider this point to gain maximum effect.

Timbers that contain a high oil content generally vaporise with a good contrasting effect. Cherry wood and maple would be too of my favourites. These woods also tend to have quite fine grains that enhance but do not interfere too much with the image itself. Oak, for example, is not a favourite of mine because the coarse variations in the look and density of the wood can detract from the effect of the image being marked.

Although it is a slow machine, a plotter format laser engraver is best suited where the application requires a mark made over a large area and especially where a high degree of detail is required because the Plano convex lens of the plotter produces the smallest possible focal point, which provides for the highest possible resolution.

Just note however that even when using a lens with the smallest possible focal point, the size of the pulse into wood is far larger than with other materials that vaporise, such as cast acrylic, and certainly a lot larger than materials that do not vaporise, such as laser marking anodised aluminium. This is because the pulse into wood continues to grow in size a little after the pulse has been delivered and also that in order to achieve a good, contrasting effect, most laser engraving to wood has some depth (deeper = lower resolution).

When using a plotter, in terms of resolution it is not beneficial to raster engrave with hatch spacing greater than 0.08mm (300dpi). Higher resolutions can in fact cause the dot pattern to merge and reduce the perceived resolution of the laser engraved photo. Some of the best photo etching to wood work that I have seen has actually been produced with a hatch spacing 0.10mm (250dpi).

Good system software will allow you to adjust the dot pattern of the image at the laser engraving machine itself, however, for machines that do not provide for this, such as those that work via a print driver, it’s important to match the graphical image resolution with the resolution of the machine itself (image resolution in dpi = focal point size and hatch spacing).

Laser engraving photos to wood is quite a slow process and if this is your core business then nothing beats the speed of a galvo laser. Typically, for this process a galvo laser will be somewhere between x3 and x10 (or even faster!) than the speed of a plotter for this application. Therefore, if you plan to grow your business in this field and so long as the image is no larger than 175mm (approx 7”) consider carefully investing in a galvo laser engraving machine because a single galvo system can be an overall much lower cost investment as it can produce at the rate of a whole factory full of plotters and with far lower maintenance issues too.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions ideally configured for laser cutting and laser engraving wood. Our experts would be happy to recommend which configuration best suits your application.

Source:- http://lotuslaser.blogspot.com/2016/04/laser-engraving-photos-to-wood.html

Laser Marking and Engraving Glass

The word ‘glass’ is an all encompassing name given to materials that can have significant variations in chemical and other properties, however, it is most commonly used to describe various forms of silica based transparent materials that are often quite fragile in nature such as spectacles, drinking vessels, vases, etc.

Aside from the chemical differences in many forms of glass, variations in process of manufacture contribute towards making glass a material that is somewhat wide in scope and inconsistent in make-up. Even glass of the same make-up and shape can vary in size due to thermal inconsistencies during the cooling process, therefore, unlike most other materials glass can be difficult to laser engrave with a highly consistent effect.

At shorter laser wavelengths glass is generally transparent, allowing the beam to pass through. For example, the lower layer of a 1µm f-theta lens found in a laser marking machine is made from glass. However, with a specially configured 532nm green laser it is possible to mark some forms of glass within the material itself to create some stunning effects.

For surface laser marking glass the 10.6µm laser wavelength is most suitable.

When marked by laser glass will not vaporise. When exposed to a 10.6µm laser, glass thermally reacts and micro cracks are formed. During the laser marking process it’s very important not to thermally overload the material as the desired micro cracks will form into larger material fractures that will flake away from the main body of the material causing an undesirable effect. To minimise this risk, techniques like marking through wetted newspaper or marking through dish soap are often used where this surface applied additive acts as a heat-sink to minimise any thermal overload to the glass itself. Use of such additives can however significantly reduce throughput.

Aside from the laser wavelength the optical configuration of the laser engraving machine has the biggest influence on how glass appears after it is laser engraved. The focal point of a galvo laser can be as many as x5 the size of a typical plotter laser. Therefore, marking hatch filled designs is best performed by a plotter laser. When using a galvo laser the best results are created by only marking vector lines.

The plano convex lens of the plotter format laser engraving machine provides for the smallest possible focal point, as small as 90µm, which delivers a high energy density and a very locallised thermal reaction the result of which is a mark closest to resembling that of chemical etching or sand blasting. This type of machine is best used for marking higher value items such as presentation awards, for example.

However, laser engraving glass with a plotter laser can be a very slow process, often taking minutes to produce.

For more industrial applications a galvo laser is often the only system that can be used because it will create a mark in mere seconds. Actually, for simple marking applications like laser marking wine glasses with volume fill lines a galvo laser can produce a mark well under a single second, so fast that the mark will appear after the laser has finished; much the same way that the sound of thunder can follow the flash of lightening.

Today, most plate glass for fenestration is marked by a 10.6µm galvo laser and whole new processes such a nucleation of beer glasses can only be produced with this type of laser marking machine because aside from the rapid marking speed a very long focal length is required for the laser to reach into the bottom of the glass.

At Lotus Laser Systems we manufacture a wide range of laser marking, laser engraving and laser cutting machines. Our experts would be happy to recommend which configuration best suits your application.

Source: http://lotuslaser.blogspot.com/2016/03/laser-marking-and-engraving-glass.html

Laser Cutting and Laser Engraving Acrylic

Polymethyl Methacrylate (PMMA), more commonly known simply as acrylic, sometimes with the trade names of Perspex or Plexiglas, is one of the most popular of all materials to laser cut or laser engrave .

Available in a huge range of colours and finishes, acrylic is easy source, relatively inexpensive and easy to fabricate. It’s no surprise then that acrylic is one of the top plastics used for making signs, point of sale displays and machine guards to name but a few uses of this amazingly versatile material.

Acrylic is manufactured by one of two processes: Cast or Extruded .

Each process produces a material with slightly different physical, chemical and machining properties.

Cast acrylic is by far the best material to use for general applications. It has better scratch resistance and transparency and is available in a wider range of colours and thickness. It has a higher melt point so when laser engraved it will result in a clean, off-white frosted effect similar to that of sand blasted glass.

Extruded acrylic is lower cost and of a more consistent thickness. Its lower melt point provides for an almost polished effect when it is laser engraved, which provides well for processes such as reverse paint filling and it is easier to thermoform into shapes.

In a laser cutter or laser engraving machine shorter wavelength lasers cannot be used for laser cutting or laser engraving acrylic as they pass through the material. Acrylic absorbs the 10.6µm laser wavelength, more commonly known as a CO2 laser. At this wavelength acrylic acts as a waveguide, which allows for a far greater thickness of material to be cut than other materials that do not waveguide, such as wood for example.

When laser cutting acrylic the constant wave (CW) properties of a DC (glass) CO2 laser provides for a superior smooth polished edge.

When laser engraving acrylic the superior beam quality and speed of pulse of the RF (metal) CO2 laser provides for a excellent uniformity of mark and a higher resolution too, especially when laser engraving at high speed.

If the job allows, the protective film should be left on while the acrylic is cut and careful consideration should be given to the type of machine table used because acrylic is easy to damage through backward laser reflection. A table with lamella bars is by far the best to use to minimise this.

Careful attention should be given to the rate of extraction and air assist delivered through the nosecone. Too little and the material may flame, potentially catching fire; too much and the degree of polishing of the edge will be diminished.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions ideally configured for laser cutting and laser engraving acrylic. Our experts would be happy to recommend which configuration best suits your application.

Source:- http://lotuslaser.blogspot.com/2016/03/laser-cutting-and-laser-engraving.html

Cooling for a Low Power CO2 Laser

CO2 lasers generate heat as a by-product of the beam generation process. If this heat is not removed effectively it can cause the laser to overheat and at best perform unreliably and shorten the working life of the laser or in a worst scenario the laser can fail catastrophically.

An effective and efficient cooling mechanism is therefore a vital element of the laser cutting or laser engraving machine design and function.

For low power (<100w) laser cutters there are in simple term two types of laser source:

1)DC excited; generally made from glass

2) RF excited; generally made from metal with some now being made from a ceramic.

DC lasers are significantly less efficient than RF lasers and as a consequence they generate a higher heat load so they must be water-cooled. Most modern RF lasers are so efficient that air-cooling is perfectly adequate up to 100w.

Air-cooling is performed by positioning a number of fans around the laser cavity and by moving ambient temperature air over the surface of the laser the heat is removed. Air-cooling is a much tidier, lower cost method of cooling a laser, however, it can be somewhat noisy, especially for higher power lasers where the air flow must be increased to remain effective.

Water-cooling RF lasers is a more reliable and efficient cooling method, however, it adds significantly to the cost of the laser cutting machine so it’s not common to find RF lasers being water-cooled that are <100w. Higher power RF lasers generate significantly higher heat loads and so must be water-cooled.

All DC lasers require water-cooling. Some very low cost machines incorporate what is no more than an aquarium pump to recirculate a reservoir (a bucket) of water. This is a wholly inadequate and somewhat unsafe design for cooling a laser as the water temperature will consistently rise to a point where the coolant (water) is too hot to effectively remove heat from the laser. Also, it is wholly unsafe to have open containers of water close to any electrical device.

Professional, well designed laser cutting machines incorporating a DC laser will use a specifically configured recirculating water chiller. Here the coolant is pumped around the laser to pick-up the heat then returned through a cooling mechanism, which lowers the coolant to a set temperature. The function is similar to that of a radiator in a car. The coolant temperature is monitored by the unit, which self-adjusts to increase/decrease the rate of cooling and maintain the set-point.

It is important to note that devices like this require periodic maintenance, such as frequent replacement of the coolant for example. If the coolant is not changed frequently it can contaminate and in turn cause contamination of the laser itself resulting in a catastrophic failure.

Well designed water-cooled laser cutters will also incorporate a flow sensor so that the laser cannot be accidentally operated when the cooling unit is not powered-on or should the cooling unit fail.

I cannot emphasis enough just how important it is to effectively cool the laser source as significant variance in thermal load to the laser is the single biggest cause of premature laser failures.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions and we have installed machines all over the World to the widest range of environments. Our experts would be happy to advise you on this or any other aspect of your laser system installation.

Source:- http://lotuslaser.blogspot.com/2016/03/cooling-for-low-power-co2-laser.html

Choosing the Correct Focal Length of a Lens for a Laser Cutter

In a previous article we explained the types of lens that can be used in a laser cutting machine. The most common lens type used in a low power (<100w) laser cutter is the Plano convex lens.

These lenses are available in a variety of focal lengths to provide for a range of varying beam profiles and focal point sizes. When laser cutting sheet materials many people get confused about which focal length of lens to use.

A short focal length lens, like 1.5” for example, provides for a very wide beam profile with a very small focal point to deliver maximum energy density. For laser cutting applications this lens is best used for thin materials such as laser cutting paper, laser cutting card and laser cutting wood veneer because the smaller focal point provides for minimal kerf; kerf is the width of the cut.

When thin materials retain heat they are susceptible to warping, which causes a defocus leading to deteriorated output quality and material waste. The smaller focal point of the 1.5” lens delivers less heat into the edge of thin materials so the 1.5” lens can help to minimise warping.

A long focal length lens, such as one with a 4” focal length, provides for a narrower beam profile but a larger focal point. When laser cutting thick materials the profile of the beam is the most important factor because a narrower profile will be more consistent in width as it passes through a material of greater thickness.

As a very rough guide, you can use a simple formula to choose the appropriate lens for the thickness of material you want to cut as follows:

Focal length of lens in inches x n = max material thickness in mm where n is 2 for the shortest focal length and for each lens thereafter is n+1.

For example:

A lens with focal length 1.5” x2 = Change to a longer focal length after the material is 3mm thickness

A lens with focal length 2” x3 = Change to a longer focal length after the material is 6mm thickness

A lens with focal length 2.5” x4 = Change to a longer focal length after the material is 10mm thickness

A lens with focal length 4” x5 = Change to a longer focal length after the material is 20mm thickness

No matter what the lens used, considerations with regard to available maximum power and the wave guiding properties of the material must be considered too. For example, it’s generally not viable to use a 4” focal length lens with a 10w laser.

At Lotus Laser Systems we manufacture a wide range of laser cutting, laser marking and laser engraving solutions. We pride ourselves on the quality and depth of knowledge of our support staff. Our experts would be happy to advise you on this or any other aspect of your laser system operation.

Source: - http://lotuslaser.blogspot.com/2016/03/choosing-correct-focal-length-of-lens.html

Preventing Fires in a Laser Cutting Machine

Some suppliers include warning devices within their laser cutting machines designed to indicate the presence of a fire and would have you believe that material flaming during laser cutting of potentially flammable materials, such as laser cutting acrylic, laser cutting wood or laser cutting card is a normal part of the process.

Nothing could be further from the truth.

Allowing the material to flame is at best an incorrect use of a laser cutting machine and at worst a very dangerous risk of causing a major fire. Flaming during the laser cutting process will damage the material as well as deteriorate the system optical components leading to wasted time, wasted materials and expensive repairs.

Allowing the flaming to develop into igniting the material is extremely dangerous and nothing short of user negligence.

If the material is flaming it indicates a serious fault in the process that could relate to a misguided use of the equipment (incorrectly specified machine and/or inappropriately trained operator), incorrect parameters being used, incorrect focus or optical configuration (lens) and a variety of other common user errors.

In most cases flaming during laser cutting can be related to two specific causes:

1) An inadequate rate of laser fume extraction and/or air assist. If the vapours generated during the laser cutting process are not quickly and effectively removed from the path of the laser beam they can combust. In vapour form the material will ignite much easier than it will as a solid.

The best way to remove these fumes is by way of aggressive extraction from the underside of the material combined with a targeted delivery of high pressure through a small bore nosecone. This keeps the vapours away from the cutting point, preventing flaming.

2) An inappropriate use of the laser cutting machine. Some suppliers would have you believe that it is perfectly safe for a 30w laser to cut 20mm thickness acrylic. Just because the machine can do such a thing doesn’t mean it should. Using a laser of very low power to cut thick materials requires a very slow feed rate and sometimes multiple passes.

Also, using a lens with a short focal length (anything less than 127mm or 5” f/l) to cut thick material (>12mm or ½”) means that even for waveguide materials, such as acrylic, the majority of the material is being cut with a beam significantly out of focus. This maximises the heat absorbed by the edge of the material and in so doing brings closer the flash-point where the material ignites.

It is therefore more important that when using a lower power laser to cut thicker material, the user is even more vigilant with their supervision of the process.

Whenever the machine is laser cutting, no matter what the materials are in terms of type or thickness, the laser cutting machine should NEVER be left unattended for more than a few moments at most. We train operators to have a constant ‘line of sight’ to the machine at all times that it is laser cutting. In the event that flaming appears the process must be stopped and the system configuration and/or parameters adjusted accordingly. In the event that flaming still occurs our advice is not to continue with the process. If the user has no option but to continue while the material is flaming then we advise to do so with a great degree of caution and a real understanding of the risks being taken.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions and we pride ourselves on the quality and depth of knowledge of our support staff. Our experts would be happy to advise you on this or any other aspect of your laser system operation.

Source:- http://lotuslaser.blogspot.com/2016/03/preventing-fires-in-laser-cutting.html

Control Options for Efficient Use of a Laser Cutter

Although there are now a large number of suppliers of laser cutting machines there are primarily just two design principles of how to control the machine.

Some manufacturers prefer to use an on-board user interface with a buffer to which the user downloads a file via some kind of graphics or CAD package through a print driver. The user then selects the file to run via the laser cutting machine user interface. This type of control for a laser cutter has a limited level of functionality and will have a finite buffer file storage capacity, so there is a limit to the number/size of files that can be downloaded to it. Another downside of using this design is that the commonly used buttons, such as START for example, will wear-out at which point the whole panel needs changing, which for some machines can be an expensive part swap.

An alternative way to control the laser cutter is directly from a PC. This kind of control is more like the advanced CAD/CAM interface found on high-end CNC machines with the most functionality and virtually no limit to the size/complexity of the job file. However it can be more risky to control the laser cutter like this if during production the skill or experience of the user is limited or even, for example, for security reasons the operator is not allowed access to the PC. Controlling the laser cutting machine in this way can also be more time consuming, especially if the system is of a larger format and the PC is some distance away from the main laser cutting area.

Some laser cutting machines offer a combination of both of the above options so that the operator can select the method that is best suited to the skill of the operator and the application at hand.

Sometimes the operator can use the two methods for one job. For example, during initial set-up a skilled operator will use the enhanced CAD/CAM functionality of controlling the laser cutter from the PC but at the point where production starts and possibly another lower skilled worker is used for the labour, the operator can download the file to the laser cutting machine so that that all the operator has to do is to handle the materials and press the START button on the machine interface.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions. All of our laser cutting machines incorporate both of the control methods described above. Our experts would be happy to advise you on this or any other aspect of how best to configure a laser cutter for your application.

Source:- http://lotuslaser.blogspot.com/2016/03/control-options-for-efficient-use-of.html

7 Tips to Buying a Laser Engraving Machine

1) Focus on the core application: laser engraving or laser cutting It is easy to be allured by how many other applications a machine can perform. A good all-rounder is a compromise machine in almost every aspect. Just because a machine can cut as well as engrave doesn't mean it can do both functions very well. Machines designed for a specific purpose will always perform the core application better so it should be no surprise that a laser cutter will cut better than a laser engraver and vice versa.

2) Throughput (how many parts produced per hour) is almost always the key to commercial success. Speed of production is of paramount importance even if right now your business volume is low. Higher throughput will deliver the opportunity to lower your sales price while simultaneously increasing your margin and you can deliver faster too. These three elements are the key to competitiveness, winning and growing your laser engraving business.

3) Consider carefully the true cost of ownership as this has a huge impact on profit erosion. Nobody intends to buy a laser engraving machine to use for just a year and then throw it away. To most this is a long term investment but the majority of buyers focus primarily on the purchase price. The real cost of a machine should be judged by the cost of ownership over its entire working lifetime, which for a good machine will be approximately 10 years. Commonly, cheap machines cost far more to own by way of replacement parts, excessive maintenance and lower output quality/productivity. The best indicator for a high cost of ownership is a machine built with consumable components so be wary of sales hype such as 'easy to change' or 'cheap to fix'.

4) Consider the technology first then consider the brand. We often see whole workshops installed with rows of the same laser engraving machines where the buyer has made purchases based on 'we always by brand X'. If a brand can supply the right machine for the job then brand loyalty certainly has many advantages, however, performance of the technology should be a bigger priority.

If we all stuck to brand only purchases then we'd all be using Nokia or Motorola phones today. It's often newer and sometimes smaller companies that deliver innovation simply because they have to in order to enter a market or even to survive so before you buy, take a good look at what else is available from the lower profile brands before you consider buying what you are used to. A look beyond page #1 of Google can save you a small fortune.

5) Buy from a well established, reputable supplier that has knowledge of applications as well as the kit they are selling.

You would expect most providers of machinery to understand the product they are selling but this should never be taken for granted. Before buying push the salesperson to test their knowledge of the product, how it functions and especially their knowledge of applications. Don't settle for a preset demo that's been tried/tested by the manufacturer.

If the salesperson does not understand your application how can they recommend to you an appropriate system configuration? Remember that many sales people will try to sell you what they want to sell rather than what you should be buying. It is unfortunately all too common that we see companies using the wrong tool for the job because they were misinformed.

6) Look carefully at warranty and support guarantees.

Despite the hype, especially on the Internet, the only guarantee that you can rely upon is that nothing lasts forever: all machines will fail at some point. The more successful you are then the harder your laser engraving machine will work and the more likely it is that it will suffer a fault. If you are fortunate enough to be successful there is never a good time to have a machine down

When a failure occurs you want to know how quickly it can be fixed and what the overall cost will be so look carefully at the small-print of system warranties and look even more carefully at the support resources of the supplier. If you can, talk to a support technician or two as well as the salesperson as these types of people often speak very differently about the same product.

7) Remember the core fundaments to a good system design is a careful balance of Functionality, Affordability, Reliability.

A system that is more functional is often by default less affordable and can actually be less reliable. A system that is more affordable is by default less functional and can also be less reliable. Logically, an average machine will be a happy medium of all of these things but an average machine will most likely deliver no more than average results.

It's therefore of vital importance to 'buy right' and choose a system that can deliver to the demands of today with a percentage of ability to cover some of the demands of tomorrow.

This consideration is not just about laser power, laser marking speed, etc but is also about software capabilities too. Today you may need to mark text and logo but tomorrow you may need to laser mark barcodes, for example.

Don't buy a Ferrari if you have 3 kids to take to school and don't by a Nissan Micra if you want to race along the German Autobahn. If you need to do both then in this analogy you actually need two different machines. The same is often true for a good laser engraving workshop.

Source:- http://lotuslaser.blogspot.com/2016/03/7-tips-to-buying-laser-engraving-machine.html

The Importance Of A Good Environment For A Laser Cutter

The environment where you operate your laser cutter or laser engraver has a fundamental influence on the efficiency, reliability and long-term working life of the machine and its components.

All lasers generate heat as a by-product of the process inefficiencies so the room temperature is of a major concern. over heating can cause a catastrophic and somewhat expensive failure of the laser. The effective removal and control of this heat is key to prolonged and reliable use. All lasers will have an inbuilt cooling mechanism by way of fans (air-cooling) or some kind of chiller unit (water-cooling).

Most people understand this, however, an often overlooked aspect to temperature is how cold the environment gets, especially when the laser cutter is not in use. Even in the hottest of countries the temperature can fall to below freezing overnight.

During weekends and other non-working days, some environments are not temperature controlled so the temperature can fall/rise to abnormal levels. Extremes of temperature will cause many elements within the machine to expand and contract. This is particularly bad for RF lasers manufactured from metal.

Humidity is another influencing factor. High humidity, especially when combined with rapid changes in temperature, can cause condensation to form on sensitive electronics components, in turn causing those components to short-circuit.

An ideal ambient temperature for the room is between 15-30c. Rapid changes in room temperature can also cause adverse reactions. For these reasons we see spikes in support calls after times of long public holidays, such as Christmas for example.

TDusty and oily environments are not suitable to site a laser cutting machine because a build-up of dust/oil can cause components to overheat, moving parts can seize-up and optical components can fail through external contamination.

Laser cutting machines should not be placed near to any source of heat/cold/air such as radiators, fans or air conditioning units and they must not be placed near to south facing windows where solar gain may cause overheating issues.

As with any form of electrical device a laser cutter must be protected from water and any form of moisture as well as unstable power supplies.

Some workshops incorporate machines that generate significant vibration, which can cause optical elements in the laser cutter to misalign.

The floor type is often overlooked as a potential influencing factor. All laser cutters should be placed on a flat and stable floor. As the machine becomes larger and heavier this is more of an issue. Mezzanine and other flexible types of floor are not suitable as they can cause the system frame to twist in turn causing the motion system to bind.

If the environment is industrial and the above factors cannot be mitigated consider building a room within it where the laser can be isolated from the potentially harmful factors of the main factory area.

As a general rule of thumb, the best environment to place your laser cutter is one where you are comfortable to work while wearing normal, office style clothing.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions and we have installed machines all over the World to the widest range of environments. Our experts would be happy to advise you on this or any other aspect of your laser system installation.

Source:- http://lotuslaser.blogspot.com/2016/03/the-importance-of-good-environment-for.html

The Effective Use And Maintenance Of Lamella Bars In A Laser Cutting Machine

For most applications where you are laser cutting sheet materials, such as laser cutting acrylic or laser cutting wood, by far the best form of cutting table is one that incorporates lamella bars.

Lamella bars are stronger and more resilient than other forms of cutting table and we’ve written other articles to explain this in detail. With this article we shall overview the best way to use and maintain your laser cutting machine lamella table.

One of the main benefits of a lamella bar cutting table is the way in which it deflects any laser power that passes totally through the material away from the underside of the material. This prevents adverse material reaction and minimises the risk of flaming

If the machine is fitted with an underside extraction design the larger spacing of lamella bars also provides for greater efficiency oflaser fume extraction.

The surface edge of each bar supports the weight of the material. These bars are very strong and will not deform under the heaviest of materials being placed inside the laser cutter.

Depending on the job at hand, it’s often desirable to remove as many of the bars as possible so that the overall surface area of the bars holding the material is minimised. This further increases the cutting quality and extraction efficiency.

Judge carefully how many mars to remove. Too few bars and the material may deform. Also, it’s important to consider how the cut parts will fall through the gaps in the bars. Spacing bars that allow materials to kink upwards but not fall through completely must be avoided, especially where the laser cutter is fitted with a nosecone moving close to the surface of the material as kinked/traps parts may collide with the nosecone.

High debris applications, such as laser cutting wood and laser cutting card will contaminate the cutting table faster and to a greater degree. Unlike other forms oflaser cutting table lamellas are not consumable items and can be cleaned. We recommend setting aside a small number of bars that can be in the cleaning process while others are being used in the laser cutter.

Lamella bars can be cleaned by simply wiping them down with a light detergent. If they are highly contaminated then they can be soaked overnight in a weak mixture of light detergent and water. Be careful not to use a corrosive cleaning agent as the bars will be made from aluminium and when old some of the protective anodised layer will be removed.

In the UK we have the brand products Cilit Bang and Mr Muscle. Both brands make products for degreasing, usually labelled as a kitchen cleaner, and these are good for cleaning lamella bars in a laser cutter.

Spray each bar directly with the cleaner. Allow it to sit for 1-2hrs. Dilute 1 part cleaner to 20 parts water and use a decorator’s plastic wallpaper tray to hold enough solution to cover the bars. Place the pre-soaked bars in the tray and leave overnight to soak. In the morning, remove the bars and wipe down with a clean, wet cloth. Usually, the bars will then look as new

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions and we pride ourselves on the quality and depth of knowledge of our support staff. Our experts would be happy to advise you on this or any other aspect of your laser system maintenance.

Source:- http://lotuslaser.blogspot.com/2016/03/the-effective-use-and-maintenance-of.html

Contaminated Optics within a Laser Cutter

Some of the most important components of a laser cutter are the optical elements. These are components that either deflect the beam (mirror) or allow the beam to pass through (lens).

Even when completely new, all optical components will cause some degree of attenuation: in other words, remove a small amount of laser power. Therefore, especially when the design of a laser cutter incorporates a large number of optical elements the laser power that arrives at the lens is less than the power that emits from the laser source.

Contamination of the optical elements of a laser cutting machine causes further attenuation and if left unchecked can have a massive detrimental effect on cutting speeds and in turn production efficiency.

Attenuation is more of an issue where the laser cutting machine incorporates a laser source of a lower power.

For example, if a laser cutter outputting 30w incorporates four mirrors, a combining optic for a positional diode and finally the lens, then if each element draws 2 watts of power the net attenuation is a 27% (almost 1/3rd) power loss.

Contaminated optics can often draw much more than 2w of laser power so it’s quite possible that a laser cutting machine <50w can be losing more than half its potential power simply through optical attenuation and/or contamination.

Laser optics will suffer accelerated contamination if the main application creates a high amount of debris; for example, laser cutting wood or laser cutting card. An ineffective or incorrectly specified exhaust system will further compound this problem

Low levels of contamination of laser optical elements can be easily cleaned, however, if the contamination is allowed to build-up too much it is often impossible to remove. At some point an over-contaminated optic will draw so much power that the heat generated will cause it to fail catastrophically.

For these reasons optical elements within a laser cutting machine are deemed consumable items so for users where the laser cutter is of strategic importance it’s a wise precaution for the user to hold stock of replacement optics.

Over-cleaning of optical elements can cause undesirable removal of the coatings, which is almost as bad as not cleaning them enough. As a general rule of thumb it is the frequency of checking for contamination that is more important and optics should only be cleaned if they show obvious signs of contamination.

With most system designs, optics that are closer to the focal point will contaminate faster than those that are closer to the laser source so, for example, inspection of the lens should be performed far more frequently than the first mirror.

We cover the cleaning of laser optics in another article.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions and we pride ourselves on the quality and depth of knowledge of our support staff. Our experts would be happy to advise you on this or any other aspect of your laser system maintenance.

Source:- http://lotuslaser.blogspot.com/2016/03/contaminated-optics-within-laser-cutter.html

Plano Convex Lenses for a CO2 Laser Cutter

In an earlier article we explained about the two main types of Zinc Selenide (ZnSe) lenses used within a laser cutting machine and that the most commonly used of these is a Plano (flat) Convex (curved outwards) lens

Aside from physical dimensions this type of lens has three defining characteristics:

1. Focal Length (F/L): the point from the lower (flat) surface to the point of beam convergence
2. Focal point: the point of beam convergence
3. Depth of focus: a range measured between a point above and below the focal point in which the lens delivers a desirable result.

The focal range is application specific and will vary depending on the material being processed and whether the application is laser cutting or laser engraving.

During manufacture, by variation of the convex surface the point of convergence can be shortened or lengthened and in turn the size of the focal point and depth of focus will vary too

As with photography, selecting a specific lens for certain applications can enhance significantly the output quality; for example, a close-up lens or a telephoto lens. The same is true for lenses within a laser cutting or laser engraving machine.

Lenses in a laser cutter are interchangeable.

By increasing the focal length of the lens, the truncation of the beam becomes narrower and the focal point becomes larger. This is particularly useful for laser cutting through materials of a greater thickness or for laser engraving surfaces that are not uniformly flat because longer focal length lenses have a greater depth of focus.

Some manufacturers refer to long focal length lens as a 'cutting lens' and a short focal length lens as an 'engraving lens'. Technically, this is not accurate.

Longer focal length lenses are more useful when engraving high debris materials, such as wood for example, where the greater distance between the lens and the material provides for a lower risk of lens contamination.

Using a lens with a short focal length will have a very wide truncation with a very narrow depth of focus, so the uses for such a lens are very limited, however the resulting very small focal point provides for the highest possible resolution and also for maximum energy density of the laser; good for removing more material in a single pass. A good use for this type of lens would be marking photographic detail or engraving rubber stamps

The short focal length lens is commonly misunderstood as being only for laser engraving. Actually, it can also be useful for some laser cutting applications. For example, some materials are very heat sensitive and a lens with a very small focal point is less likely to draw heat away from the cutting point into the material causing adverse effects, such as material warping.

In a typical laser cutting or laser engraving machine the range of Plano Convex ZnSe lenses will be as follows:

1. 38.1mm (1.5”) F/L: high resolution engraving, <1mm material thickness cutting
2. 50.2mm (2”) F/L: good resolution engraving, <5mmmaterial thickness cutting – this is the best 'all-round' or 'general purpose' lens
3. 63.5mm (2.5”) F/L: lower resolution engraving, 3-10mm material cutting
4. 101.6mm (4”) F/L: low resolution engraving, 10-20mm material cutting

Lenses of longer focal length are available but only used for cutting and will not generally be suitable for smaller format machines

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions with a variety of lens options. Our experts would be happy to advise you which configuration would suit your application best.

Source:- http://lotuslaser.blogspot.com/2016/02/plano-convex-lenses-for-co2-laser-cutter.html

Types of Air Assist for a Laser Cutter

Most laser cutting machines will incorporate some form of air or gas assist the function of which is three-fold:

• To improve the efficiency of the laser cutting process. Generally, this works by the positive air keeping vaporised debris away from the path of the beam in order that all of the laser energy is applied to the material.
• To improve the quality of output. This works by the positive air helping to keep vaporised debris away from the surface or the edge of the material being laser cut so that contamination of the material is minimal.
• To reduce the requirement for maintenance (cleaning) and prolongue the life of optical elements. This works by positively pressurising air at the focus carriage (the laser head) so that contaminants are kept off of the sensitive surfaces of the optical elements.

Well designed laser cutting machines will provide for all three of the above functions.

Some machines do not incorporate a nosecone. These are not good for laser cutting but are sometimes better for laser engraving because without the nosecone the laser head is lighter in weight, so it can move faster with lower vibration. If these machines have air assist then it’s usually delivered via a small bent metal tube delivered at an angle to the work surface at the focal point. The angled air assist helps to dislodge debris, pushing it into the flow of the extraction across the material surface.

It’s important to note that unless the laser fume extraction is very well specified then this type of directional air assist can cause premature contamination of the lens. At Lotus we do not favour this design of air assist.

For best results when laser cutting the laser head will incorporate a nosecone, which will sit a few millimetres away from the surface of the material. At the end of the nosecone will be a small hole through which both the beam and air assist are delivered. If the bore of the hole is too big and/or the distance of the nosecone from the material is too great then the whole process of air assist becomes very inefficient.

Nosecones with smaller holes work better as they direct the air more locally through the cut instead of around the cut. The smaller hole also helps to increase air pressure and allows for a smaller air pump to be used. In case where a gas is used instead of air, such as nitrogen for example, a small nosecone is essential to minimise the waste of a potentially expensive gas.

An often overlooked aspect to the design of air assist is the hose bore (diameter) through which the air flows from the pump to the nosecone. Many machines use a tube with a bore that is too small. This greatly reduces the volume of air that can flow through it.

Using a larger bore air assist delivery tube reduces the speed at which the motion system can run but greatly increases the efficiency of the air assist process. With some models of Lotus Laser Systems it’s common for customers that process high debris materials like laser cutting wood or laser cutting card for many hundreds of hours without the need to clean the optics. Conversely, many machines on the market with poor air assist designs will require almost daily cleaning of optical elements.

One important point to note is that when a nosecone is fitted air assist MUST always be used otherwise the process can work in reverse and the lens can quickly suffer contamination and even catastrophic failure.

Lastly, it is very important for the laser cutting machine to be able to activate the air assist through its control software.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions with a variety of air assist options. Our experts would be happy to advise you which configuration would suit your application best.

Source: http://lotuslaser.blogspot.com/2016/02/types-of-air-assist-for-laser-cutter.html

Efficient Extraction From a Laser Cutting Machine

Most people when evaluating which laser cutting machine to purchase perform a simple tick-box exercise listing the various functions and features as listed in the manufactures sales brochure. Few actually analyse those features in detail to see how well designed they are and even fewer test those features to see how well or efficient they work.

Inefficient laser fume extraction is very costly in terms of increased maintenance, decreased throughput, poor quality output (wasted materials) and reduced component life. Bad extraction will be hazardous to the health of the operator and is the biggest cause of flaming (fires) in Laser Cuttes.

One of the most misunderstood and overlooked aspects of a laser cutter is the efficiency of the laser fume extraction design. In the majority of plotter format machines, extraction is taken from a vent positioned at the rear of the worktable. This causes fumes to be drawn over the surface of the material.

This type of extraction is generally OK for laser engraving but not at all good for laser cutting because the rising fumes block the path of the beam, dropping laser efficiency. The direction of air can cause lightweight materials to move on the worktable and this design of extraction often allows contaminants to contact with the laser head. The platen used in almost all such machines will quickly contaminate, causing a restriction with air-flow

Some of the larger format machines utilise extraction from the laser head by way of a long, flexi hose. Again, this only works for engraving but it has many inherent faults. Firstly, the hose contaminates fast, restricting flow and dropping efficiency and with constant flexing it will perforate over time. Because of the narrow hose diameter the vacuum pressure needs to be very high and the volume of air that can be taken in this way is very low. It’s therefore not possible to use an extract to atmosphere system with this type of local extraction. This type of extraction cannot be used when cutting small parts and/or lightweight materials as they can be pulled into the path of the beam by the air-flow.

By far the most efficient way to extract from a laser cutter is from underneath the material. We call this Underside Extraction or UE for short. This causes a vacuum underneath the material, which if the blower is strong enough can hold slightly warped materials flat to the work-table. This is especially useful for laser cutting paper, laser cutting leather or laser cutting textiles. When combined with a well designed air assisted nosecone UE will pull the laser fumes down through the cut line virtually eliminating any chance of those fumes contacting the laser head. This will often increase edge quality, especially for high debris cutting applications like laser cutting wood and reduces maintenance in some cases to near zero.

Well designed UE will provide for an even pressure and flow of air across the whole worktable so the best machines incorporate some kind of funnel underneath the worktable with the point of extraction placed centrally to the funnel.

The best laser cutting machines will incorporate dual extraction ports: one to draw over the material and another from the underside.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions and can supply a wide range of extraction solutions. Our experts would be happy to advise you which configuration would suit your application best.

Source: http://lotuslaser.blogspot.com/2016/02/efficient-extraction-from-laser-cutting.html

Extract to Atmosphere for a Laser Cutter

In an earlier article we discussed two main types of laser fume extractionfor a laser cutting machine one of which was laser fume filtration and the other Extract to Atmosphere (ETA). Here in this article we take a more detailed look at the correct design of an extract to atmosphere system.

This is a highly specialised subject. Most laser cutting machine andlaser engraving machine suppliers as well as many fume extraction suppliers do not truly understand what is required to provide for an efficient, well performing extract to atmosphere set-up for a laser cutting machine.

By some standards ETA is merely a small turbine with enough flexi-hose to hang out of the nearest window. Nothing could be further from the truth or in fact nothing could be more inadequate and potentially dangerous than this type of set-up.

For an ETA system to perform well and most importantly for it to be safe, the contaminated air within the laser cutting machine must be quickly removed and expelled well beyond roof height where it will quickly dissipate into the atmosphere safely.

This requires moving very large volumes of air, a by-product of which is the generation of high levels of noise. This is the main reason why some sites, such as those in inner cities, simply are not suitable for ETA.

Start at the laser machine by connecting a 1m flexible hose from the extraction port to some kind of gate. The gate will be used to control flow as well as shut-off the machine from cold/damp air that may enter from outside when the system is not in use.

The type of flexible hose is critical; under no circumstances use cloth or foil types of flexi hose as these are designed for very low pressure extraction, such as tumble-dryers, and they will collapse and perforate.

The only type of flexi hose to use is made from PU, sometimes treated to be ant-static and with very strong reinforcing wires. Use a transparent version as you can then monitor the level of contamination and change it when necessary.

After the gate the duct must be made from galvanised steel with at least 150mm diameter. At each join it must be riveted and sealed using a suitable mastic. This duct will widen to match the diameter of the fan inlet. From the fan it will be a constant diameter to match the fan outlet.

The fan MUST be positioned OUTSIDE of the building so that the duct from the laser cutter is under vacuum. This is safer because if the duct is compromised fumes will not escape from it into the work environment. If circumstances allow, site the fan on the floor as it will be easier to service.

The performance of the fan is critical to the efficiency of the machine and should be specified by a professional making careful calculations for the size of the laser machine and the length/design/resistance of the duct.

To reduce noise, just before and just after the fan fit a pair of attenuators. These act similar to the baffle box on a car exhaust.

Beyond the fan outlet attenuator the duct should run in a straight line upwards to a point 1m beyond the roof line or apex of the building. The duct should terminate with a jet cowl and NOT any other type of duct cap.

Careful consideration should be given to the discharge point to allow for maximum dissipation of the expelled air and minimal nuisance to neighbours
This type of set-up will provide for many, many years of use with next to no deterioration in performance and little to no required maintenance.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions and can supply custom designed ETA solutions. Our experts would be happy to advise you which configuration would suit your application best.

Source: http://lotuslaser.blogspot.com/2016/02/extract-to-atmosphere-for-laser-cutter.html

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Laser Cutting on a Lamella Table

In an earlier article we discussed two types of table used in a laser cutting machine one of which was a lamella table. Here in this article we take a more detailed look at this type of cutting table.

A lamella cutting table is essentially a series of thin bars laid on edge onto which the material to be laser cut is placed. These bars can be manufactured from sacrificial material such as acrylic or more commonly they are made from anodised aluminium.

If made from aluminium the shape of the bar is critical to its effectiveness. A well designed lamella will be shaped like an arrow head with a slightly rounded tip, which is the point where the material comes in to contact with the bar. Such a shape will deflect any laser beam that passes through the material away from the underside thereby minimising or even eliminating any backward reflection.

This is particularly useful for transparent materials such as laser cut clear acrylic, heat sensitive materials such as laser cut mirrored acrylic or materials that contaminate very easily because of the high amount of debris they produce, such as laser cutting wood.

A well designed laser cutting machine with a lamella table will allow for reasonably thick and therefore heavy sheet materials to be placed upon it without any distortion.

The best machines incorporate a design where the lamellas are easily removable. This allows for the removal of bars that are not required, reducing the surface area that the material is held by to a bare minimum and thereby creating a total void beneath the material.

Well made lamellas will last for many years and unlike the alternative, more commonly found honeycomb table, lamella bars can be cleaned, will not distort and so are not a consumable item. Should the bars ever require replacement then they can be replaced just a few at a time for a negligible cost.

For processing sheet materials like laser cutting acrylic or laser cutting plywood a lamella cutting table will produce results that far surpass that of any other form of cutting

When combined with a well specified laser fume extraction system, especially when extraction is from the underside of the material, cleaning of the laser cutting machine will be massively reduced in frequency.

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions with many types of cutting table. Our experts would be happy to advise you which configuration would suit your application best.

Source:- http://lotuslaser.blogspot.com/2016/02/laser-cutting-on-lamella-table.html

Laser Cutting on a Honeycomb Table

In an earlier article we discussed two types of table used in a laser cutting machine one of which was a Honeycomb table. Here in this article we take a more detailed look at this type of cutting table.

The honeycomb cell structure is made from what are essentially very thin strips of aluminium that are in some places glued together. This glued section is then extruded, concertina fashion, to form a sheet of honeycomb shaped cell structures.

This honeycomb material is actually designed to be laminated between two sheet materials, for example MDF, where it's used primarily in the construction industry. The resulting 'sandwich' board is very light weight and very strong, however, without this lamination the opposite is true; the honeycomb is incredibly weak.

The idea behind using this honeycomb is to minimise the occurrence of backward laser beam reflection; where the laser beam passes through the material into the honeycomb cell there is a void that allows the beam to pass well out of focus and so not reflect back into the material.

In some respect this works and a honeycomb table can be good for cutting non-rigid materials such as laser cutting textiles or when the requirement is to laser cut very small parts, however, because of the weakness of the structure it deteriorates very fast. It is also impossible to clean this type of table and problems occur when placing heavy materials upon it and/or when using extraction from below the material.

Therefore, this type of cutting table is truly a consumable item and frequent replacement can be costly over time.

Common faults with a honeycomb are that the aluminium sheet deforms, which actually can cause the very backward reflection that this type of table is trying to avoid. When processing heavy material, such as laser cutting acrylic, it can have a tendency to sag, casing for beam defocus. Once dirty it can cause debris to stick to new materials and using it with higher power CO2 lasers can actually cause the cell structure to separate.

Furthermore, there are limitations with regard to the overall size of a honeycomb cutting table.

In short using a honeycomb cutting table often has more limitations than benefits so unless it is your only available option or your application is one of the few where a honeycomb table works well it is far better to use a lamella type table when laser cutting sheet materials

At Lotus Laser Systems we manufacture a wide range laser, marking and engraving solutions with many types of cutting table. Our experts would be happy to advise you which configuration would suit your application best.

Source:- http://lotuslaser.blogspot.com/2016/02/laser-cutting-on-honeycomb-table.html

Cutting Tables For CO2 Plotter Lasers

For low power (<100w) CO2 cutting lasers one element of the machine that is often overlooked and misunderstood is the worktable.

The design and type of worktable can have a significant difference on the performance of the laser machine, the working life of its components and the quality of its output.

Most systems that are commonly available on the market today will consist of one or a combination of the following worktables:

• A stainless steel plate: This type of worktable is usually found in machines designed primarily as a laser engraver. For most laser cutting applications this type of table produces very undesirable results and requires significant maintenance (cleaning) even after the smallest of jobs.
• Honeycomb table: This type of worktable is manufactured from very thin aluminium that is glued and extruded to form a honeycomb structure onto which materials are cut. The design of this table is to minimise backward reflection and to allow hot gases and particulates to pass away from the underside of the material.
• Lamella table: This type of worktable incorporates thin bars that are usually made from anodised aluminium and indicates that the system has truly been designed as a laser cutting machine.

Most users would have had experience of a honeycomb table because this is the type of table supplied by most of the major EU and US laser machine manufacturers. Such tables are not very robust as the honeycomb material was never intended to be used in this way and will quickly deteriorate by way of bending and impact damage as well as contaminating very fast.

Therefore a honeycomb table is deemed a consumable item because it cannot be cleaned or repaired and with frequent use will require replacement in a number of months if it is to perform correctly. This is not a cheap item so it is therefore no wonder why equipment manufacturers like to incorporate this table in their machines!

It is however a good solution for laser cutting textiles and similar non-rigid materials.

For laser cutting acrylic, laser cutting wood and other rigid sheet materials a lamella table is a far more robust solution. In a good machine the lamella bars are very strong, allowing materials of a greater size/thickness/weight to be laser cut and the bars can be easily and quickly cleaned. It’s therefore common for these bars to last for several years of heavy use and replacement bars are often very low cost.

For best results when laser cutting rigid materials a high performance laser fume extraction unit should be combined with a lamella table as this combination delivers the ultimate solution in almost every aspect.

Source:- http://lotuslaser.blogspot.com/2016/02/cutting-tables-for-co2-plotter-lasers.html

Beam Delivery For A Laser Cutting Machine

For the majority of laser cutting applications the material is in a sheet format.

The advantage of the plotter mechanism when used as a laser cutter is that the beam can be delivered with a consistent power and minimal variation in focal point over a relatively large area.

When the CO2 laser power is <100w the types of material that are processed are usually non metals; materials such as acrylic, card, wood, textiles, etc. These materials are most efficiently processed at the 1000x600mm size, which provides for minimal material wastage, maximum efficiency of fume extraction and part loading/unloading.

Sectors that would benefit from using this type of machine are architects for model making, sign companies and point of sale fabricators to name but a few.
In recent years there has been a big increase in the number of educational facilities such as schools, Universities, etc who buy a laser cutter for schools to assist with Design & Technology subjects.

This type of machine is available in a range of laser powers typically from 25-100w. Higher powered lasers will deliver faster cutting speeds and often a superior edge quality but will also cost more to purchase as well as more to maintain/own over time.

This type of machine will typically be fitted with a plano-convex lens delivering a short focal length, such as 2.5” for example. The short focal length should be combined with a nosecone to deliver an air assist close to the material for increasing edge quality and minimising lens contamination.

An often overlooked part of the machine is the software. Most machines in this format are designed for laser engraving, which often is the least efficient way to use such a machine. Therefore, the software tends to be designed for the engraving process. This can be significantly limiting when using the laser as a cutting tool.

A good laser cutter will use software similar to that of a CNC router and have optimising features to minimise wasteful motion control movements as well as improving the output quality of the part that has been cut.

At Lotus Laser Systems we manufacture a wide range of plotters systems for laser cutting and our experts would be happy to advise you which configuration would suit your application best.

Source:- http://lotuslaser.blogspot.com/2016/01/beam-delivery-for-laser-cutting-machine.html

Most Common Types Of Laser Beam Delivery

Many people don’t realise that within a laser marking machine there are different ways to deliver the laser beam to the work piece and even fewer consider the massive difference that choosing the correct form of beam delivery can have on process times and output quality.

Contrary to popular conception it is not a good idea for a single format of system to be applied to all jobs even if technically it’s possible to do so.

Choosing the right form of beam delivery can determine whether or not you will meet customer price, quality and delivery requirements or even whether or not you will win the job at all and the wrong choice can have serious implications relating to system reliability, maintenance and running costs.

In a laser engraving machine there are most commonly two types of laser beam delivery:

1. Via a plotter type motion system that usually contains stepper or servomotors, linear bearing rails and belts. To this motion system are attached a series of 3 or 4 mirrors that deliver the beam via deflection to a focus carriage that usually contains a single layer plano-convex lens. The lens moves over the work area, which is usually large and rectangular in shape, to deliver the focused laser to the work piece; technically this is a flying optic laser.

These machines are commonly called a laser engraver or a laser cutter and predominantly incorporate a CO2 laser at the 10.6µm wavelength.

1. Via a sealed unit containing 2 mirrors that are attached to galvanometers; these are very accurate, high speed motors one of which turns through 0 degrees (X axis) and the other through 90 degrees (Y axis). The beam is focused through a fixed lens known as an F-Theta lens that at the 1µm wavelength is multi-layered and at 10.6µm is usually a single layer.

The work area is constraint by the characteristics of the lens and is usually quite small and circular in shape; technically this is known as a beam deflection laser.

At Lotus Laser Systems we manufacture at our UK facility all of the above mentioned system formats and our experts would be happy to advise you which configuration would suit your application best

Source:- http://lotuslaser.blogspot.com/2016/01/most-common-types-of-laser-beam-delivery.html

Laser Engraving Machine Basics: CO2 vs Fiber

When selecting a laser engraving machine, the first step should be ensuring you choose the correct wavelength for the material you are working with. The wavelength will ultimately determine the results you get with various materials. The two most common wavelengths are 1 micron and 10.6 microns. At 10.6µm, CO2 laser tubes are used whilst at the 1µm wavelength; fiber is generally accepted as the best all round laser source.

1µm laser engraving machines are usually used on metals although there are a number of other materials that also mark very well such as polycarbonate. The small spot size a fiber laser engraving machine offers makes it the best choice when you are looking to mark or engrave metal with a high level of detail. The 10.6µm wavelength will not react with metal at low power although people often attempt to work around this by using chemical sprays which are generally time consuming, messy and highly toxic. Aside from the smaller spot size, one of the big advantages of the fiber laser source is that it is highly durable and is generally going to have a much longer life than the CO2 laser source which means you should get many more years of life from your machine. As expected, you are likely going to have a larger initial outlay when choosing the route of fiber technology.

10.6µm is the most common laser source and is often used to engrave wood or plastic and is what you are likely to see fitted to most standard flat bed laser cutter. Like fiber laser tubes, these can actually be delivered using both galvo and plotter systems although many people have not yet realised the major advantages of engraving with a galvo as opposed to a plotter. As mentioned, CO2 lasers are more geared towards dealing with woods and plastics so if you are working with these materials 10.6µm is certainly the way to go. One of the advantages of working with CO2 laser tubes is that their cost is generally significantly lower than their fiber counterpart. The trade off is that their expected life is shorter so you should be prepared to have to replace the tube more frequently.

Overall, there are a number of complex factors that will play a part in determining the right laser engraving machine for you. However, selecting the correct wavelength for your application should certainly be your number one priority.

Source:- http://lotuslaser.blogspot.com/2016/01/laser-engraving-machine-basics-co2-vs.html

Use Of Different Types Of Laser Machines

Everything which looks perfect requires high accuracy and precision, whether it is a decorative wooden architecture, impressive greeting card or a glass light fixture. A good quality laser cutting machine is essential for the professionals who believe in producing fine detailed job to the accuracy. There are different types of laser cutters which are used for cutting different types of materials like glass, wood, paper, leather, metal, plastic, textile and stone. These types of cutters are able to cut the material into different degrees of thickness for providing the accurate results.

Nowadays, every company is using the technique of engraving. It is used to personalise their product with their company trademark. There are different types of laser engraving machines available in the market depending upon the size and applications. These machines are highly advanced and sophisticated. They don’t directly touch the material to be engraved; instead the laser beam is applied on the material to leave a clean and flawless impression on the material.

With the changing time, the technology of marking the material has also evolved. Nowadays, every industry is using the laser marking machine to mark their respective materials. These machines are able to mark the material with the permanent mark. They also provide good quality of flexibility and accuracy.

These machines are fast, flawless and accurate in their job. Hence, if you are interested in expanding the business than purchasing these laser machines will be very fruitful in the future for the business.

Source:- http://lotuslaser.blogspot.com/2015/12/use-of-different-types-of-laser-machines.html