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Cheap plastics that machine and turn nice?

huleo

Hot Rolled
Joined
Feb 12, 2014
Location
UT
Currently working on a little device that can be made from about any plastic. I currently have Nylatron that machines nice but way to expensive to make too many of these gadgets. Curious what you guys would reach for on the cheap? Need some maybe 2x2 square sticks and rounds.

I find Nylatron mostly pretty easy to work with but cutter selection is key.
 
For milling I'd say acetal, abs, pvc, or nylon. Any particular characteristics you're looking for in the material?

For turning acetal is going to be about the easiest to break a chip in. By the time take a deep and fast enough cut to break pvc you'll likely start noticing specs of tear out on the surface. Rough it fast and only the finish pass is an issue.

Abs and nylon hardly seem possible to break.

If it's on a manual or open cnc machine a shop vac will pull the chip off as you take the finish pass.

Cut your eyeball sharp tooling is the ticket. Polished carbide tooling for aluminum seems to work well. I find if the tools have touched anything besides plastic they tend to be problematic.
 
HDPE machines nice, breaks a chip better than UHMW and also doesnt string as bad when sawing. I agree with the shopvac, I use it myself esp on the lathe.

Charles
 
Only real requirement is some minor chemical resistance. PVC has been used before without any issues at all.

I am curious how pricing compares with all of these? Not that I need to beat this thing to the penny but always been amazed what we spend on Nylatron I guess. And of course we MUST use that brand and extruded only.


Probably will come down to something available in many dimensions. At least saw cutting should not cost too much!

The problems we faced with Nylatron was chipping at the corners but I think this was mostly due to aggressive Aluminum cutter geometry.
 
I build tons of stuff from PVC. I keep several sizes of solid rounds on hand and can have plate sawed for the square and rectangular shapes I need. Love it, about 75% cheaper than Delrin.I use pecking cycles for turning while roughing to break the chips.
 
Delrin is not cheap compared to PVC or HDPE and interestingly, it doesn't like high pH at all. If you need some chemical resistance you should check whether whatever plastic you want to use is OK with that chemical. Acetone for example is fine with some plastics but terrible with many others.

I'd vote for HDPE as it's very recyclable compared to PVC but the latter is good to machine for sure.
 
Go to McMaster and compare prices. They also include machinability ratings. After you find what you want then shop around at the plastic supply houses.
 
Already been said... PVC.. Its cheap and its not that bad to work with as far as plastics go.

Its no where near as big of pain in the ass as UHMW or Teflon... Might as well try hanging onto a big
wad of chewing gum while its still all wet and bubbling with spit.

If I had my choice, ALL machined parts or at least the ones I have to make would be
made of black delrin (Ass A Tel). So easy to work with and black delrin makes the best looking parts.
 
Delrin, definitely. If you use sharp tools, there won't be any burrs. If your tools aren't sharp, you can deburr it with a toothbrush.
 
We are talking easy to machine and cheap...

I usually consider application then look in that direction for easy to machine and cheap in the parameters required.


Nylatron is a lube impregnated poly...Your paying extra for that, is it required to have lube properties? If not Nylon would be my thought...but again why was this material chosen in the first place? Maybe just what was on hand and it stuck as "The Material to Use"



Personally, if I have to machine plastic...I like Acetal.

Can be cheap...can also be expensive. I have a customer that has no requirements for the part other then the perfect color...unfortunately the quantity is not high enough for me to run my own dye lot so the only material available is Medical Grade and we pay through the nose for it....and that's when its available.
 








 
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