Author Topic: Some help, please!  (Read 589 times)

Offline lloydsp

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Some help, please!
« on: June 20, 2020, 18:41:31 pm »
I almost-always mill either 6061 aluminum or PVC foam plastic, and I have my cutters optimized for that work.

But, occasionally, I must mill polyethylene or ABS, and my tools and speeds just don't work.  I just don't have any experience with the materials (except bad ones). 

Chips don't get ejected (even with full-flow coolant), they just make long strands that collect around my cutters, and make me pause the machine every minute or two to clear curls from the cutter.

Any advice?

Thanks,
Lloyd
"Pyro for Fun and Profit for More Than Fifty Years"

Offline Dragonfly

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Re: Some help, please!
« Reply #1 on: June 20, 2020, 19:27:42 pm »
A polished single flute cutter for plastics may help you. A new one which hadn't cut anything else. And more aggressive feed (resp. chip load). 
I've done little HDP work. So not much experience.
Currently I am making some parts out of solid PVC. With a 2 flute 4 mm carbide cutter for Aluminum at 1600 mm/min and DOC per pass 2-3 mm. With an acceptable result.
But they are quite different - solid PVC is hard, cuts OK but softens at quite low temp. Polyethylene is 'greasy'. The tool must be very sharp.

Offline lloydsp

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Re: Some help, please!
« Reply #2 on: June 20, 2020, 19:38:06 pm »
Fly, yeah.
I've got brand-new, perfectly-sharp carbide tooling, but it's 4-flute (never used before today).  I may have to buy more tools!  It looks like I might be getting more of this business.

Lloyd
"Pyro for Fun and Profit for More Than Fifty Years"

Offline Bubba

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Re: Some help, please!
« Reply #3 on: June 20, 2020, 20:34:08 pm »
I've got brand-new, perfectly-sharp carbide tooling, but it's 4-flute
********************************
Lloyd, that is the main reason for your problem. I past I have used successfully high rake 2 lute ONLY, brand new cobalt endmills. Rpm/feedrate set anywhere for .003-.005 chip thickness. Good luck.
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Offline lloydsp

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Re: Some help, please!
« Reply #4 on: June 20, 2020, 21:41:08 pm »
Thank you.  I can have 2-flutes or 1-flutes here in two days.

Lloyd
"Pyro for Fun and Profit for More Than Fifty Years"

Offline Bob La Londe

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Re: Some help, please!
« Reply #5 on: June 20, 2020, 23:30:29 pm »
I have a few single flute mills just for machining various thermo plastics.  Precise Bits makes some nice ones. 


I do mostly 6061 aluminum, and medium carbon steel.  I have different mills for each of those too.
Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

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Offline Garyhlucas

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Re: Some help, please!
« Reply #6 on: June 21, 2020, 00:07:38 am »
My last job everything was HDPE. Two flute cutters, high feed rates, relatively low spindle speeds we only had 5k. I even had some special profile router cutters made and they worked great.
Gary H. Lucas

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Offline lloydsp

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Re: Some help, please!
« Reply #7 on: June 21, 2020, 01:20:05 am »
Thanks, all of you.  It's obvious I need to get some new cutters, if I'm to continue with these plastics!

Lloyd
"Pyro for Fun and Profit for More Than Fifty Years"