Machining Urethane?

[augshastry]

Anyone have any advice on machining Urethane. I figure on using brand new HSS tools and flooding with coolant, cut can't find any info on Speeds and Feeds. Relatively simple part (outside the fact of it being rubber). So drill and and mill info would be greatly appreciated. Oh yeah, it's Durometer hardness is 70A, and from what I've read most anything below 90 is usually cast. :/

[Matthew Hajicek - Singularity]

I'd say you're likely in experimental territory. Good luck and let us know what you find!

[Biker]

Use a good sharp HSS 2 flute tool. I don't recommend using coolant. Sometimes it will cause to much part or tool deflection. A good blast of air should work well.

[augshastry]

Okay, and I forgot to mention depth of cut and finish passes? I figured that .05 as a finish would be okay, less chance for th etool to rub and generate heat, right?

[Pilot Plant Supervisor]

I've heard of people keeping the parts in the freezer before machining, but have never tried it myself.

[augshastry]

Yeah we talked about that, but I figured it would be a waste of time, seeing as the part will heat up as we're cutting, and it'll just make the temperature change more extreme.

[augshastry]

Well, the parts have taken a backseat to a bunch of other hot stuff, but I'll keep it upadated once I eventually get around to playing with them. Again, any suggestions, tip,s or, tricks wil be greatly appreciated.

[Pilot Plant Supervisor]

I'll be watching...I'm curious to see how it turns out.

[Mic6]

Sandwich between metal?

[Jeremy Herron@DBS Solutions™]

I have done a little with it. I always freeze it in dry Ice, and it cuts like uhmw, Sharp tools and get it done before it has time to thaw. HTH

[90rsgnuguy42]

I always freeze it in dry Ice

 

This is how I've always seen it done as well.

[andate caga]

Have done this before. It was a milled part. I needed 3 it was 100% r&d. I froze the stock 2in round. Put in 4th axis and went as fast as I could with HSS tooling. Low rpm high feed. Don't make heat. No coolant, it draws away the cold. The CTE is crazy also. I had to hold +\- .01. Took 10 bad ones not get my first good one but after that I had it nailed. Good thing is that it's cheap material.

[Bill Henderson]

We had a job that they way wanted cut before they had an extrusion made to verify whether or not it would work. basically 1x3x6 inch rectangular block that when finished was .08-.110 wall thickness u-shaped part with .1 radius at bottom of channel.

 

Couldn't get the results we had hoped for. Didn't try freezing the vice though. Heat dissipated too quickly from the jaws.

[mkd]

the urethane we run is speed and feed like aluminum at room temp with coolant or without.

 

any leftover islands can snap off leaving a "gouge". better to leave .20" stock if you are aggressive or the tool is dull.

 

and yes the stuff can dull carbide. it takes a while.

[Jaz]

If it is a 2D profile have it water jetted.

[MIKO ELLO]

I know this post is old but, how did it turn out? 

I have some round 75 Shore A Polyurethane that I am trying to turn on the CNC lathe.

I have used Dry ice by itself and then Dry ice + Acetone which worked nice on a facing path but, problems on the OD.

I wanted to try liquid Nitrogen but, worried it might be too cold.

I have been using sharp carbide inserts for aluminum like a .007r CNGP and it cut okay when the part was cold.

Anyone have some ideas on what else I could try besides having them molded?

[MIKO ELLO]

I have tried HSS bits ground up but, still had problems with the parts deflecting and not cutting that well. I may just tinker with the feeds and speeds 

 

[mkd]

what problems?

Iv'e never turned the stuff

[MIKO ELLO]

3 minutes ago, mkd said:

what problems?

Iv'e never turned the stuff

Polyurethane 75 Shore A durometer is almost like rubber. It's hard to machine but, I have seen few posts of people asking the same questions. The OP has made this post several years ago but, did not see if he was able to solve the problems he was having

[crazy^millman]

Freeze it and allow for shrinkage in your program.

[Roger]

I have had really good luck cutting urethane with left hand spiral end mills!  1/4" endmill 12000 RPM, 100 IPM feed, with air blow.

View link below for picture of the part.

http://s404.photobucket.com/user/rdantesbattleground/media/20180322_083402_zps98mfrjm4.jpg.html

 

 

[Ben Peters]

What's up? Your going to wanna cut it with stone if possible. I had to cut threads on that material before so I made a fixture on a spindex that would follow the thread I had to put on the part when I turned the spindex. I ground a 60 deg. on a thin stone and drove myself crazy over the course of 3 days ... had thousands to do. Good luck!

[mkd]

HSS corncobb works

don't laugh at feed rates, 11pm on sunday night with only two toe clamps......