Finish on soft plastics

[Dean jeffery]

Been struggling with the finish on plastics but only soft stuff like nylon and HDPE the left parts are acrylic and are totally fine, the right is nylon and it's shite.

Anybody got any speeds and feeds for me to try I run the acrylic at 24k 1750 feed, nylon I've tried anything from 800-1750 and the results appear very similar.

Cutter is one from cutwel tools 2mm single flute and specially for soft plastics, DOC is 1mm

[m_c]

Are you climb or conventional milling?
Do you have good chip clearance?

[Dean jeffery]

Tried both climb and conv with very little difference, I just use a dyson and dust boot.
Chip clearance is not perfect but I've also fully cleaned parts down and done 2 opps to try and get better finish.

[magicniner]

I use single flute cutters from 1mm to 6mm with compressed air to clear chips out of the cut, it also cools the work and the cutter, if you use a big hypodermic with the point ground off as a nozzle it doesn't take much air and you can get the nozzle pretty close to the action,

- Nick

[Dean jeffery]

I will rig up my air blast on the next batch of parts and see if this helps matters, customers ain't said nothing but I don't like doing shity work

[Dean jeffery]

Think I found the issue same place I get the HDPE from same cutter same speeds and feeds but better finish, only the very bottoms got recut chips.

Easy to see from the pic not so easy on the eye, so my best guess is different batch of material or a crap batch before.

[A_Camera]

Why are you using 2mm cutter for this? Generally i think 4 or 6mm 2 flute would be better. You could also increase the feed rate with a larger cutter. It is also a good idea to make a final fine cut at full depth.

[Dean jeffery]

More parts per sheet, some small parts are made from that same sheet, less tools to stock, less tool changers.

But I could get away with a 3mm cutter on that part without an extra tool change, I've done a finish pass on some 10mm acrylic with the same 2mm cutter to give a clean cut in the past.

Only really any good doing full clean up passes on new cutters or soft material other wise you still get cut lines.

[m_c]

That latest photo looks more like a flex/resonance/chatter problem, which is much harder to address.
First option would be a dial indicator mounted on the cutting area, with the needle against the spindle/cutter, and see if there is much movement when you pull/push the cutter.

[Dean jeffery]

The photos do make things look worse than appear, the cut lines can't be felt with the nail when run on the edge.

Every time I've cut that material I've only had 2 decent results one been above, that's why I posted up I was convinced the speeds and feeds was the reason.

But I'm now leading towards the materials spec is way off, the customer sends the material I just cut it.

It's cheap from direct plastic and tbh if not personally buy from there, nothing comes new and never as protective film on.

Cheers for the help and suggestions though guys.