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Machining plastic

Machining plastic

Machining plastic

Can anyone provide some guidelines for feeds and speeds for machining plastics?  We have several vacuum formed parts that require secondary machining.  We have experimented with a variety of tools as well as feeds and speeds with limited success and I need to get a better handle on the details.  What are the best tools (ie. carbide, HSS, 2 or 4 flute, ect)?  Thanks is advance for your replies.


Mark Downey
American Injection Molding

RE: Machining plastic

It really depends on what type of plastic. But generally you should use a 2 flute endmill. Lots of coolant. Run your spindle as high as you can . Feed about .010" chip load.This should give you at least a 125RMS finish.
Good luck

RE: Machining plastic

The key to machining plastic in general is a sharp cutter w/ lots of chip clearance.  There for I would suggest a HSS 2 flute end mill.  You can get plastic to cut with carbide, but HSS is better!

RE: Machining plastic

i am machining platic and the one person told you to use coolant. we dont here becuase of the mess and i find it doesnt work that good with coolant. but i think a 4 flute end mill works better then a 2 flute. use speeds and feeds similar to alluminum i found works really good for the platic we are using.

RE: Machining plastic

Thanks for all the replies.  They have been informative.  I have actually come accross a VERY nice tool for cutting plastics.  The tools are from CMT, http://www.cmtusa.com/. ; These tools are giving us a burr free finish.  They have a steep helix and come in both up cut and down cut configurations.  The down cut helix does a great job and it does not pull the parts up off of the fixture.  I am very pleased with these tools.  They are also two flute tools which I have found are recommended for cutting plastic because they take larger chips without melting the plastic.  Again thanks for the feedback.


Mark Downey
American Injection Molding

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