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Metal laser cutting FAQs
Josh Judkins
posted this on May 18, 2011 17:40
Laser cutting metal is not quite the same as cutting plastics and the other materials we offer.
Laser cutting metal is great for relatively simple designs like electronic housings or lamp shades. If you want to make jewelry or something more intricate out of Stainless steel your design might be better suited to a new metal fabrication technique we are trialling called Photochemical Machining (PCM). The formatting requirements are slightly different for PCM so contact us for the guide.
These FAQs include tips and tricks that will help you design and make successfully using metal.
What you must know for laser cutting metal with Ponoko?
- What is possible with metal laser cutting?
- You cannot share cutting lines.
- Parts must be bigger than 0.4x0.4" / 10mm x 10mm
- Parts must have a 0.25” / 6mm separation in your design file.
- Designs should not have features smaller than 0.02” / 1mm.
- All parts must be defined with closed paths.
- Parts will be tagged into the surrounding waste material
Read more detail about these points here.
What are the main differences between cutting metal and cutting other materials?
There are two main differences:
The laser cuts to the side of the line instead of cutting on the line.
Metal laser cutting takes into account the width of the cutting beam or the laser kerf. Draw your designs at the size that you want them and the laser will automatically
The laser pierces the material in the 'waste' before it starts cutting.
You need to allow about 5mm/0.20" of ‘spare’ material around your design that the laser can pierce and cut in.
Can I combine cutting lines?
It’s not a good idea. In the making guide, we suggest combining or minimizing cutting lines to reduce laser cutting time and therefore cost. This works for most materials, but with metal parts will just fall out or skew and cause all sorts of problems.
The design on the left will cut out of, say, plastic or wood as two parts. If you want to make the same two parts out of metal, you need to draw them as shown on the right. This is because you need to leave spare material on one side of the line for piercing and cutting.
Is there anything I should watch out for when designing corners and holes?
Yes. The laser beam has a noticeable diameter to it so all ‘internal’ corners have a radius of 0.5mm (0.02 inch). 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 (0.04 inch) 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.
Extremely acute angles (generally less than 10o) also pose problems as this is, in effect, the same as having two cutting paths too close together.
Can the laser handle intricate designs made out of metal?
No. Metal doesn’t laser cut very well once it gets hot so any parts with too much detail are likely to turn out poorly. You should't have positive or negative features that are smaller than the material thickness. ie holes shouldn't be less than 0.9mm.
When the metal gets too hot it can splatter damaging the (rather expensive) machine. That’s why we sometimes have to reject metal parts with too much detail.
Can I cut really small pieces out of metal?
Yes, we can cut parts with sizes down to 10mm x 10mm, 0.4"x0.4".
One of the benefits of laser-cutting metal is that you can cut small pieces and they will hold together. The downside is that small pieces are easily lost. This is because the bed of the metal laser cutter has gaps about 70mm square (~3 inches) between the supports the material rests on while it is being cut. To get around this, 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.
Some pieces are too small to keep. Small waste pieces will fall through the bed and not be included in your package. If you are concerned about which parts will be delivered, please send us a PDF showing the pieces you want to keep.
Can I engrave or etch the surface?
No, at present you can only cut metals.
Do coupons apply to metals?
No, coupons are not applied to metals.