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Things you must know for Laser Cutting metal from the NZ hub.

Dan Emery
posted this on September 10, 2012 11:58

What you must know for laser cutting metal with Ponoko in NZ?

What is possible with metal laser cutting?
You cannot share cutting lines.
Etching or engraving is not possible for metal laser cutting.
Parts must be bigger than 10mm x 10mm
Parts must have a 6mm separation in your design file.
Designs should not have features smaller than 3mm.*
All parts must be defined with closed paths.
Parts may be tagged into the surrounding waste material
Parts will have slightly radiused corners

What is possible with metal laser cutting?

Metal laser cutting is great for simple designs like electronic housings, lamp shades and foldable structures etc. If you have intricate jewelry designs you need to adhere to the minimum feature size rules outlined below.

The materials available are 0.9mm Stainless steel, Aluminum and Brass.

You cannot share cutting lines.

All designs must be isolated. There can be no joined or nested parts. This is because there needs to be spare material on one side of the line for piercing and cutting.

Etching or engraving is not possible for metal laser cutting.

Metal laser cutters are not able to etch or engrave on the surface of the material so we can offer cutting only. If you upload a file with engraving colors in it the metals option will NOT be available to select from the drop down menu.

Parts must be bigger than 10mm x 10mm.

There is a minimum part size of around 10mm x 10mm. Parts smaller than this are too difficult to process and generally cannot be made.

Parts must have a 6mm separation in your design file.

You need to allow about 6mm of ‘spare’ material around your design for the laser to pierce in and lead into your design.

Designs should not have features smaller than 3mm*.

Metal doesn’t laser cut very well once it gets hot (it can splatter damaging the (rather expensive) machine) so any parts with too much detail are likely to turn out poorly. You generally should't have positive or negative features that are less than 3mm*. This is why we sometimes have to reject metal parts with too much detail.

*Stainless steel can withstand heat better than Aluminium and Brass and can have a minimum feature size of 1mm.

The laser beam has a noticeable diameter to it so all ‘internal’ corners have a radius of 0.5mm. This means, for example, if you want to cut a triangular hole each of the corners will have a radius and will look slightly rounded. A 1mm square hole looks like a 1mm circle. To be on the safe side, the diameter of a hole should be no less than the material thickness.

All parts must be defined with closed paths.

We need to do a small amount of processing to your file before we send it off to production. All blue outline cuts need to be closed paths for our file conversion software to work accurately and for the laser to follow the line smoothly.

Parts may be tagged into the surrounding waste material

This is because the bed of the metal laser cutter has gaps about 70mm square between the supports the material rests on while it is being cut. To avoid the loss of smaller parts, the laser cutter ‘tags’ small objects so that they don’t fall through the laser bed and get lost and/or damaged. (See the diagram for an example.) This means objects will still be attached to the waste material when you receive them – all you need to do is twist them to pop them out. There will be a small amount of material left where the ‘tag’ was which you can remove with a metal file.

Parts will have slightly radiused corners

External corners also have a slight radius due to the way the laser cutter is programed to travel around corners.