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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.
 

Tonytn36

Diamond
Joined
Dec 23, 2007
Location
Southeastern US
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.
 

BOSTON

Stainless
Joined
Oct 5, 2006
Location
Boston,Mass.
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
 

JCSparks

Aluminum
Joined
Jan 10, 2009
Location
Grafton
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.
 

metlhed

Stainless
Joined
Jan 17, 2007
Location
Ohio
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
 

APMJBREWER

Plastic
Joined
Nov 12, 2008
Location
NC
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
 

KilrB

Stainless
Joined
Feb 18, 2007
Location
Angleton, Texas
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.
 

T-BONIMUS

Aluminum
Joined
Dec 29, 2008
Location
OREGON
If Turning Use Mitsibushi Hti-10
Milling Use Mitsibushi Bxd Facemill
Profiling, Slotting Pocketing... Use Hanita 4k02 (2 Flute Carbide Endmill)
 

ASARGENT

Cast Iron
Joined
Feb 6, 2007
Location
DAVIS, ILLINOIS
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.
 

CalG

Diamond
Joined
Dec 30, 2008
Location
Vt USA
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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