Laser cutting silicone sheet

Anyone have any experience laser cutting 1mm thick silicone sheets on a laser cutter? We’ve been trying to find settings that will cut all the way through without completely destroying the material in the process. So far no joy. We’re using an 80W Trotec but I would think the process would be similar for any CO2 laser.

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If you figure this out please post your results! I would be interested in this capability.

Not sure what kind of things you’re making, but you could also consider casting silicone to make custom parts. @Metal_Janet has done that.

@Hekseskudd has recently been milling silicone sheet, with acceptable results for a functional gasket. There’s been discussion of freezing it for better machining. See yesterday’s scrollback in #machine-shop on Slack.

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One of our staff members is trying to cut silicone gaskets. Freezing and milling sounds like and interesting solution. I’d be interested in hearing more about that process.

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At Science World I would routinely laser-cut red silicone sheets to make flat gaskets. I had reasonable success with it, although the laser would leave a sooty residue that could be washed off with soap & water to reveal a fairly clean cut edge. Our laser cutter nozzle was hooked up to the shop air with a lot of airflow, so I wonder how much of the cutting was done by oxidation (similar to a plasma cutter) vs laser ablation.

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On a related note, now that we have killer shop air at VHS, would our laser benefit from that kind of setup?

I think for simple 2d profiling a drag knife attachment would perform better. I used a single flute end mill designed for plastic. I noticed deflection at the cut and offset my vectors to attempt to compensate for the deflection. It would be interesting to see how stiff the silicone would become with freezing. The particular type I was machining was rated to -70C so I suspect the improvement would be minimal. Still worth a try. I needed a stepped gasket with raised ring so I was area clearing down partially. I noticed that in the z axis the material machined perfectly. So I suspect that containment laterally would improve the x and y machining by not allowing the material to deflect as much.

It’s hard to say. We used the shop air instead of the small crappy air pump that came with the laser since it was one less piece of equipment to maintain. We would just need to make sure that our exhaust system could handle the additional volume of air being added to the laser cutter, otherwise it’ll vent smoke and fumes into the room

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From the research I’ve been doing, many folks have recommend a relatively high pressure air assist during the cut. Sadly, the air assist is down on our laser and awaiting a service call to have it repaired. However, even when it’s fixed the built in Trotec air assist pump is fairly anemic and there is no way to connect external air source.

As a different approach, a fellow on the Trotec users group on FB says that he uses his laser primarily to engrave silicone wristbands and occasionally cuts all the way through by accident. This morning we tried cutting via multiple pass raster engraving which has been fairly successful. His machine is higher wattage but his material is thicker so we started with his settings and the user here is now doing some experimenting to dial in a cleaner cut. We’re getting closer!

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We managed to get a clean cut by performing a deep raster engraving of the cut lines on the silicone sheet using high power, low speed, low frequency. It took several attempts with varying settings to dial in the best configuration that didn’t leave a white ash-like residue around the cut line. This process did not completely sever the silicone sheet but was deep enough that the gasket being cut could easily be pulled away cleanly without tearing the edges. The settings on our 80W Trotec were:

  • Power 100%
  • Speed 0.80%
  • PPI 1000
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A couple posts in this thread refer to “we” or “our laser” as if they’re talking about the VHS laser, but instead I think they’re referring to the laser at their other respective organizations. So to be clear for the casual reader: The VHS laser cutter is using a small dedicated air compressor that is switched on and off by the laser control system, and it’s working fine. Our air assist is not down.

When we set it up at our current location I considered using shop air since that would have allowed us to run the entire laser system at 120V. We would need a regulator to step the flow/pressure down to something suitable for laser cutting, as well as a solenoid valve so the laser control system could switch the air nozzle off when not in use.

It’s certainly a good idea! If someone wants to help make this happen, I will offer my support to facilitate the upgrade.

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Cool. I’m finishing up the air, and I’ll see how close to the laser I can get with the stuff that I have. Which side should I aim at?

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Back left corner of the laser cutter. Near the water chiller. But really anywhere back there that we can mount a regulator, solenoid, and then a short flexible hose to the cutter.

This will make the laser cutter a lot quieter! It will also let us experiment with more air assist.

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My bad. Yes, I was referring to the Trotec laser engravers we have where I work at the Wilson School of Design at KPU in Richmond. I manage the Product Design prototyping and maker workshop and support all of the laser engravers in the building. I also do contract work for the local Epilog laser distributor doing installations, service and training. I’ve never actually used the laser at VHS or any of the asian, water cooled lasers for that matter.

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Cool beans. I’ll update the LCC when I’ve got the stuff over there. Shall we set it up to have the option for nitrogen assist down the road, if possible?

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