Cutting and scoring ABS

[davehills]

I have some ABS sheet in various thicknesses, ranging from about 0.8mm to 1.2mm.

What I'd like to do is both cut it and score it for folding.

Cutting works fairly well, although I do get molten edges. However, having more difficulty with the scoring. When I go to fold the piece it cracks along the score line.

Any thoughts or tips?

[TimBobTastic]

My first thought is to apply some heat along the bend line using a hot air gun / paint stripper, this should make the material more malleable, and therefore easier to form without cracking.

The scored lines should ensure you get a nice tight, constant corner

[davehills]

That was my first thought as the material cracks whatever settings are used.

Would polycarbonate or another material be more friendly towards scoring/bending I wonder?

[TimBobTastic]

PC would definitely form without cracking.... You need to check if PC is laser safe though (sorry I am not experienced enough to know the answer to that)

[Tom]

I've bent 6mm ABS with a score line and heat bender
The heat of the laser changers the plastic so it cracks when you try and bend it
but if the score line is shallow and you use a heat bender then you should be able to bend thinner

[Spooky]

PC liberates Benzine and other nasties when cut with a laser, maybe not overly dangerous nasties in the short term but long term exposure is a class 1 carcinogen so handle with care.

[davehills]

OK, so maybe PC is best avoided!

Anything available in thin sheet (0.8mm to 1.2mm) that can be scored and bent without heat?

(I'm sure the heat-and-bend technique will work)

[Matrix]

One little word of warning regarding line bending...

We've been bending parts for a while for one of our product ranges, using a strip heater on 5mm acrylic. Seemed great - 2m drop tests onto concrete no problem, and even our burliest storeman couldn't snap them!

Hmm, or maybe not. About 6 months later after product release, and several hundred parts out there with customers, we started getting may more parts returned under warranty than usual - all with the same kind of failure at the line bends. In some cases the parts are so fragile that even a wimp like me can easily snap them by hand! But every parts was known to have passed our final QA tests etc. and we've worked closely enough with some of those customers to know that they're not "abusing" the products in any way.

Basically, anything that creates a temperature gradient across the plastic (which can include lasering, but definitely line bending), puts stress into the plastic when it cools down. The stresses make the plastic extremely sensitive to any kind of solvents (including even water vapour in the atmosphere) - the plastic becomes progressively more brittle over time without the customer having to "abuse" the product in any way at all. And if the customer does decide to clean the plastic with any kind of solvent, the process will happen much faster.

For more info, google "Environmental Stress Cracking" when you have a minute - time well spent if it will save you the kind of expense and embarrassment that we've had to deal with!

Interesting, "impact resistant" plastics like ABS and HIPS are not so bad in this respect (the impact absorbing rubber ingredient helps to stop the microscopic cracks) - so if you have ABS to hand, you might already be on the right track (watch your mirrors though, ABS will make them sooty VERY quickly unless you have very good extraction!). We've also found HIPS (High impact polystyrene) to work pretty well too - though the edges do tend to melt and "swell up" a little more than ABS does.

[Spooky]

Heat bent plastics should be "annealed" after bending although in some cases it's not really possible if the shapes are small or intricate.

Matrix raises some very good points and Environmental conditions are indeed VERY important.

cheers

Dave