Brisbane plastics, hdpe, delrin etc.

[Artvan]

Hi all,

I'm just starting out with cnc, I have a chinese machine on its way. That was step 1.

Step 2 which I should fully figured out before step 1 is getting stock to cut.

For aluminium I've been told action aluminium is the go. I have a few suppliers of acrylic to go with.

What I can't find it acetal/delrin locally in Brisbane.

Does any one have a hobby supplier of such a material or a viable alternative material that I don't know about?

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[cncmachinistplastics]

Hi Artvan,

If you're still looking for a good plastics supplier in brisbane I'd reccomend Tynic Automation (https://tynic.com.au/)

You can see their range of plastics here: https://tynic.com.au/engineering-plastics/

[joeavaerage]

Hi,
believe it or not HDPE and acrylic are actually quite hard to machine, its because they are so heat sensitive that the chips tend to weld themselves back together.
Acetal is much more forgiving in this regard, but I still use flood coolant, partly for cooling but also flushing the chips out of the cutzone.

Craig

[RCaffin]

Acrylic is MUCH worse than HDPE - MUCH worse.
I do use a bit of HDPE for jigs etc, and I find it reasonable - with new sharp cutters. Sure, there are sometimes feathers on the edges - OK, there always are feathers, but they clean off easily.

But the key to success here is to NEVER use the same cutter for hard metal (steel, SS, even brass) and for plastic. Once a cutter has bitten into steel the really nice sharp edge the mfr put on it will be gone - in seconds. No, this does not mean the cutter cannot handle lots more steel: it can. But it won't cut plastic very well. I label my cutters: S for steel and A/P for al/plastic, and I don't mix them.

Theory: the cutting action for steel is vastly different from the cutting action for plastic. The latter is like slicing, but the former is more like micro-tearing. Sounds strange, but read up on it.

Yeah, acetal and nylon are OK. So strangely enough is industrial PVC (with the right revs/feed).

Cheers

[joeavaerage]

Hi,
what I dislike about HDPE and Nylon come to that is that the chips form long strings. Acrylic, while being very heat sensitive, does form small chips as opposed to strings. Provided you keep
the flood cooling up to acrylic it cuts well. Acrylic is one of the cheaper plastics that (with cooling) I find it useful for small parts and jigs and so on.

Craig

[RCaffin]

Hi Craig

Well, I was machining HDPE today, and while it feathers a bit the rest came off as small chips. Shower of them. Sharp cutter though.
The reason I use HDPE for a lot of things is that I collected a fair bit of sheet stuff for free some time ago. Left-overs from some large jobs. Nothing beats 'free'.

Cheers
Roger