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Laser Cutting

NB: Exeter Laser do not cut metals - Laser Industries in Plymouth do.

Technically speaking, lasers do not "cut" as there is no mechanical contact between the machine and the work, everything is done with invisible to the naked eye IR light from the CO2 laser tube.

Lasers sublimate certain materials, which means they focus so much energy on a particular spot that the material under that spot is instantly raised from solid temperature to gaseous / vapour state, with no middle ground, an example of this is acrylic cutting. With other materials they cut chemically, by raising the temperature at that point to such a high level that chemical changes take place, in essence they destroy the material under the spot. With still other materials they cut by burning, raising the temperature at that point so that the material is combusted or charred, an example of this is wood cutting.

Depending on the material to be cut, and the thickness of said material, there are ranges of preferred cutting speeds and powers, and flow rates of assist gas.

Exeter Laser can cut or engrave a maximum size object of 1.3 metres wide by 3 metres long, if it is flat and not more than a few inches thick, such as a house door. If it is bulkier then the maximum object size is 1.3 metres wide by 0.9 metres deep by 0.25 metres high. Please note the maximum working area for laser engraving or cutting in one pass is 1.3 metres by 0.9 metres.

1.3 metres by 0.9 metres is also expressible as 1,300 millimetres by 900 millimetres, and at 25.4 millimetres to the inch, as 51.18 inches by 35.43 inches, but please note very well we only ever work in metric, which means we work in millimetres ONLY, please do not send us work or dxf files with dimensions in inches, or in centimetres, or metres, always use millimetres.

Exeter Laser can Laser Cut the following by no means exhaustive or complete list of materials. strike through if engrave only.

  • Acrylic
  • Anodized Aluminum
  • Carbide
  • Ceramic Substrates
  • Cloth
  • Coated Metals
  • Composites
  • Delrin
  • Fabrics
  • Fiberglass
  • Foam
  • Glass
  • Kevlar
  • Laminated Plastics
  • Leather
  • Marble
  • Masonite
  • Matte Board
  • Melamine
  • Mylar
  • Nylon
  • Paper
  • Painted Metals
  • Plastics
  • Polycarbonate
  • Polyester
  • Pressboard
  • Rubber
  • Silicon
  • Stone
  • Styrene
  • Veneer
  • Wood

Laser cutting is in many ways an interesting process.

Because the cutting is done with a beam of light, and not a physical cutting tool, there is no force applied to the work, so it does not have to be held or fixed down, although, that isn't always a benefit, and there are times when you should secure the work anyway, but the beam of light does not push the work around, or grab at it, or strain it, which is why the CO2 laser is so versatile, and can cut and engrave such a vast range of materials.

Because the beam is only about 100 to 250 microns (0.1 to 0.25 mm) in diameter at the point of focus (there are a LOT of caveats in there, what focal length lens is being used, is the optical system clean, is the point of focus aligned vertically correctly with the material to be cut, etc) you can cut very fine details, and sharp angles, as sharp as you like.

The four butterflies on the right each have a 112 mm wingspan, and were cut from 4.5 mm smoked acrylic and as you can see there are many details and features that simply would not be possible to achieve by any mechanical cutting methods. 

For many jobs, it is a CO2 laser or nothing.

There is also the question of speed, each one of these butterflies was cut in a couple of minutes, which is simply unthinkable for any mechanical process, and again, once cut, no further work or cleaning up is required, the laser cuts the actual finished product.

The 640 mm (25") high Eiffel towel in the left picture was cut from 3 mm clear acrylic, and again, you simply could not make it with anything other than a laser, some of the pieces being cut out to give that skeletal framework design are significantly less than 2 mm in size, and again, it should be stressed, what comes out of the machine is the finished work, no cleanup or other finishing is required.

Various woven materials and cloths also benefit from the laser cutting process, unlike the mechanical cut with blades or scissors which leave frayed edges to the fibres, the laser heat seals the edge being cut.

But, to return to the question of speed, because speed is a function of time, and as the saying goes, time is money.

Let's take the Eiffel tower on the left as a nice example.

You can cut the whole thing from a sheet of 3 mm thick acrylic approx 1,100 x 300 mm.

It contains over 9,200 shapes that need to be cut out, and every single one of them has to be cut out accurately or the whole thing is useless and either will not fit together, or will fit together and look awful. There is over 21 metres of cutting to be done just for the base section with the four arched legs and the lowest platform. There is over 70 metres of precision cutting to be done to make the whole model.

So, again, within the range of speeds and powers at which you can physically cut all these 9,000 + parts and 70 + metres of cutting, you have the "fast" end of the scale, where the cut edges won't be optically clear and perfect, or maybe not cut all the way through, so you break whole sections trying to pop the cut shapes out, to the slower "quality" end of the scale, and at the quality end of the scale you're cutting no faster than 15 mm/sec (which is no slouch, 15 mm/sec is 900 mm/minute which is just shy of a yard a minute) the whole job takes just about two hours of machine time, that's 80 minutes of actual cutting time and 40 minutes of moving between cuts time, but, you get a QUALITY product, with every single edge and angle and cut optically clear, and the whole thing just leaps out at you, vastly more than the sum of the parts.

With Exeter Laser, you can afford to work at the quality end of the scale, which means your products are always as good as they can be, not just as good as you can afford.

Addendum.

When cutting, generally speaking for any material over 6 mm in thickness, you will get the best results when the minimum radius anywhere in the shape to be cut is no smaller than half the thickness of the material being cut, this particularly applies to acrylic, so if the thickness of the material is 10 mm, try and aim for a minimum radius of 5 mm, or if the material is 25 mm, try and aim for a minimum radius of 12.5 mm. As you increase in thickness, again, particularly with acrylic, from 6 mm thick where this is a nice rule to follow, more or less, by the time you get to 25 mm thick, it has become a hard and fast rule...