Edge polishing of acrylics

[Robert Lambie]

any i have heard of you have mentioned mate..

im certainly no expert on this subject.. but i do often work with glass! 😮
now i know a different substrate but when i get glass with a polished edge it comes polished but has (not a radious) but a slight angled shamfer (spelling? 😆 ) both sides of the edge

. \_____/ < like this!

now as far as i know that is done in the one go! as it is polished.
would this not work with a good acrylic? 🙄

.

[Rodney Gold]

For your application a laser is the best – the striations can be minimized (they are there cos the air assist – a jet of air blowing on the point where the laser is cutting, ejects the melt out the back of the px that is being cut and recools it) Even with the striations , generally the edge finish is better than flame polishing
There is NO issue with sharp corners and de burring – and the laser can cut stuff you couldnt manually do in a million years (like 1mmx 1mm sqare inside an object with polished sides and sharp corners)
A lot of how a laser cuts is to do with beam quality , depth of focus and power distribution as well as the power of a laser
A 30 -50 watt Laser using a Coherent DEOS source and a 3-4″ lens will cut up to 15mm thick px in a single pass and will rip thu 3 mm at pretty high speeds – you take the acrylic part off the machine and pack it – there is NO further refinishing required!!!
We use 3 GCC laserpro Explorers that have 1m x 500mm bed sizes and have doors you can pass a 1m x any length piece thru.
What the laser wont do is cut bevels , it cuts straight down , but it will also engrave or frost cast with exceptional crispness and detail and will engrave it the same if you want a deeper graphic for paint filling.

If you are CnCing px , use soapy water as a lubricant , this improves the cut quality majorly , use either diamond coated or Titanium coated bits and do a 2 pass job , one almost full cut and then the second as a full cut at high speed with the minutest of offsets into the part that is cut , this will clean it and you will have almost no work to do.
flame polisihing will work with this better than a single rougher cut that requires sanding.

At the end of it all , a laser will probably speed up your production 5 fold and still doa LOT of other stuff for you apart from merely acrylic cutting
A 50 w laser like an Explorer will most likely cost around 25-28K

[chuckie38]

We have a 240watt Eurolaser with a 2m x 1.5m bed. It’s actually a Zund table so it’s pretty precise. It’s getting a little long in the tooth ’cause we’ve had it six years already and am fixin’ to plunk down 175K for another one just as soon as the dollar=Euro. 90% of what we cut the edge doesn’t matter. However I’ve been unhappy with the finished edge when we try to get quality. We haven’t tried gas assist and now that you mention it I will. Co2?
If we can get a decent edge, then we can run a beating along it and make the beveled edges with a table router as Rodney suggest that they do with glass. I would have to have a special bit made although it would have to be a small bearing if most of what we’ll be doing is 10mm
A bearing will also permit is to get the same rounded edge in a radius which diamond polishers are unable to do. It’s not a big cut and perhaps I can go straight to a diamond bit – perhaps try for a larger diameter bit – but it would be a feat of engineering to make it work.
It all comes down to labor content. I’m in a feroshiously competitive market and we need to be able to do this quickly.
I was looking at a competitor’s product and the way he gets around it is making all sharp corners – no radiuses!- so he can use a diamond polisher all the time.

[Rodney Gold]

Gas assist is vital – you actually dont need Gas per se , but just a stream of compressed air directed at the cut point , and the way of setting the correct gas assist pressure is to incres it slowly till the acrylic doesnt flame – and then a bit more for safety. You MUST elevate the acrylic off the table . we dont use a honeycomb , but scrap px blocks.
apart from that , edge quality will depend on your PII and speed – Pulses Per Inch needs to be set high , like 1000 and speed must be slow enough that there is a melt , rather than cut at 100% power and max speed , reduce the speed and reduce the power accordingly till you get a good edge.