Forums/Tutorials/Metal Laser Cutting & PCM Tutorials

Things you must know for Laser Cutting metal.

Dan Emery
posted this on February 16, 2012 16:33

What you must know for laser cutting metal with Ponoko?

  1. What is possible with metal laser cutting?
  2. You cannot share cutting lines.
  3. Etching or engraving is not possible for metal laser cutting (see PCM)
  4. Parts must be bigger than 0.4x0.4" / 10mm x 10mm
  5. Parts must have a 0.25” / 6mm separation in your design file.
  6. Designs should not have features smaller than 0.04” / 1mm.*
  7. All parts must be defined with closed paths.
  8. Parts may be tagged into the surrounding waste material.
  9. You may not receive the waste material.
  10. Parts will have slightly radiused corners.
  11. It's common for the back side for the material to get scratched.
 

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 an intricate jewelry design Photochemical machining is probably a better option. The formatting requirements are slightly different for PCM so please read the the guide here.
 
The materials available are 0.036"/0.9mm Stainless steel and 0.040"/1mm Aluminum

 

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.
Separating metal pieces

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 0.4x0.4" / 10mm x 10mm.

There is a minimum part size of around 0.4”x0.4”/ 10mm x 10mm. Parts smaller than this are too difficult to process and generally cannot be made. 

Parts must have a 0.25” / 6mm separation in your design file.

You need to allow about 0.25” / 6mm of ‘spare’ material around your design for the laser to pierce in and lead into your design.

Tagged metal piece

Designs should not have features smaller than 0.04” / 1mm.

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 generally should't have positive or negative features that are smaller than the material thickness. ie holes shouldn't be less than 1mm.

*For Aluminum the minimum feature size is 0.118" / 3mm.

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.

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.

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 of about 3 inches 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.
Tagged metal piece

You may not receive the waste material.

If your parts are not so small to be tagged into the waste material then generally you will not be shipped the waste with your designs. If there is a large section of spare material on your sheet you can add a simple cut line around the area if you want to have it included in your order.

 

Parts will have slightly radiused corners.

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

It's common for the back side for the material to get scratched.

The bed of the laser cutter is made of a steel honeycomb grating that supports the sheet of material while it is cutting. The materials, especially Aluminum, can get scratched on the underside as the sheet is loaded and unloaded off the machine. This is something that is largely unavoidable and may require some finishing, post cutting, to clean up the parts.