How to tell the difference in Black ABS VS Black Delrin?

[conceptmachinin]

I didn't seperate these when I was machining some sheets. I put the ABS with the Delrin on the shelf. I'm having a hard time deciding on what's the ABS is. Is there a tell tail sign of ABS? I know that its usually lighter in color. It cuts a little different, but I want to be sure. Any help would be appreciated.

Thanks

Jimmy

[Geof]

Take some chips or cut off a thin sliver and burn them.

Delrin is an acetal plastic and when it burns it does it with a clear, almost invisible flame, and creates formaldehyde which has a very sharp smell.

ABS has butadiene and styrene in it, same as synthetic rubber and polystyrene.When it burns it produces a lot of sooty smoke and has something of a burnt rubber smell.

And don't inhale too much of any of the smoke.

[conceptmachinin]

Thanks, that sounds like a good way to check it.

I appreciate the help!

Jimmy

[LaughingLarry]

This is just a 'by the way' post.
I see that this is an old post, but we had this same issue, and our supplier sent out a guy to look and he did some testing and was able to separate the materials. He did the 'burn' test mentioned above, but he also weighed the parts. ABS is lighter than Acetal by about 15%. Also, he has some liquid, I think it was a methylene chloride, and he put a very small amount on the parts. It doesn't touch the Acetal, but melts the surface of the ABS. Very cool to watch.
We have used these guys for years, and they do a good job. This kinda put them over the top in our minds. I bet lots of plastic places could have shown us this, but these guys did - Industrial Plastic Supply

[RomanLini]

Cool info, thanks!

I usually measure and calc cc's (volume) and then weigh it, the specific gravity tells a lot.

With Delrin and ABS you should be able to tell from the softness if you have pieces of each on hand. Tap it with a metal object (screwdriver etc) Delrin is hard enough to "tap" ABS and PE HDPE etc will "thunk" being softer.

And the best tip is when you buy new stocks write the material name on the 4 edges of the stock with a sharpie pen!

[rowbare]

For reference: The Home Shop Machinist & Machinist's Workshop Magazine's BBS - View Single Post - What is this odd plastic?

bob