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machinability of polypropylene

ASARGENT

Cast Iron
Joined
Feb 6, 2007
Location
DAVIS, ILLINOIS
anyone machine polypropylene on a regular basis? how does it machine? is it a nice cutting plastic like delrin, or is is gumming and soft like uhmw? any help is appreciated. thanks.
 
Horrid to machine. Gummy, rolls a huge thick burr (pushes material off the part ahead of the cutter). In my experience, it isn't very stable either, moves around a lot.
 
High RPM and spindle feed 2 flute (New)...make a frame cut around part first using a climb path...this will stop the burr from rolling over edge and chip out on edge
 
cutting

I use a fly cutter with a sharp high speed bit, high RPM. Make sure the cutter is turning a diameter 2 times the width of the part you are cutting.
 
Polypro is not very fun at all. I just finished an order of 50, 30, and 10 of different bores, but all got 4 holes thru from .094-.107. More hours on deburr than cutting and drilling. No matter, dry or coolant or fluid, will melt ahead of cutting edge.

You can try what you want in methods and speeds/feeds/doc. Will burr fuzzy. A good 400 grit paper will help smooth it out. Razor edge softly because it will dig with little pressure. I've found that a moderate doc, any speed, moderate feed will still melt a little, but light finish pass will clean up most of the time. Just try to have fun. :D
 
polypro

I machine polypro all of the time. it is ok, burrs easy. I use very sharp mitsubishi turning tools and always use a solid carbide I.D. threading tool for I.D. cutoff burr. I don't know if you are milling or turning but, if you are turning I can give you the ideal tool list. I mostly machine delrin / acetal, polypro, and uhmw or 316. Hand deburring for polypro is out of the question, take the time and debur it in the machine. Jon
 
High-speed steel.

Plenty of clearance and top-rake.

Hone it dead sharp.

Are you turning or milling?

I haven't much experience milling it but in turning it have had best results taking it to size in one pass whenever possible. This minimizes deflection.
 
If Turning Use Mitsibushi Hti-10
Milling Use Mitsibushi Bxd Facemill
Profiling, Slotting Pocketing... Use Hanita 4k02 (2 Flute Carbide Endmill)
 
we are turning and milling. this will surely give us a burr problem. we are quoting a high volume part at a low price. sounds to me from most of the info, we will spend more labor dollars deburring the part than we will machining it. thanks.
 
T-Bon
Good call.

Once when there was a large number of "lever arms" that needed two bores and cross drilled for pins, the debur operation was a real hold up. (D bits were used clear out the holes.)

Solution? Tumbled the works in ceramic medium with periodic replenishment of DRY ICE in the hopper.

Worked sweet, but the medium was gray in color, it left the parts burr free, but dirty looking. I should have used something white.

Ways and means, every man has 'em

CalG
 








 
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