Machining CPVC

[jspangler]

Hi

Just wondering if anyone had any idea what SFM I could use as a starting point for pvc and C-pvc??

 

My machinery handbook doesn't list ANY plastics.

 

Machining it on an old Fadal, with coolant, and HSS tools, programming in MC9.1

 

Thanks

John

[TR Mfg.]

I use about 600sfm but I think that is abit on slow side.

[Thad]

quote:

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use about 600sfm

but I think that is abit on slow side.

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I think you're right. I cut steel at 600 SFM.

 

Thad

[M. Anderson]

John,

 

Good to see you back!

 

A guy told me, "..turn it up till it melts then back off a little....", seemed to work?

 

Last of this stuff I cut was a thick walled pvc pipe of somekind the customer supplied.

 

My machine is limited to 8K on rpm - I just picked 6500 out of the air and ran all tools at that. 1/4 - 3/4 EM's and 9/16 drill. Feed was ran between 80 and 120 ipm.

 

My problems:

 

Rigidity - holding the $@&* stuff still, ended up making a steel sleeve to slide the stuff onto.

 

Flute geometry - did not have EM's specific to plastics, but ended up with some 4fl HSS. 2fl's seemed to "bang" the cut to much and mess with my setup and accuracy of cut.

 

Coolant - Fines from this crap kept cloging up coolant system. (They float!) Ended up using loose mesh HVAC filters to filter coolant before it ran back into the coolant tanks.

 

HTH

 

Anyway, Good luck...

 

Mark

[Surface]

If your cutting CPVC, it's important to realize the material has a free chlorine. When you cut it, the clorine will attach to water and create hydrochloric acid.

This in turn will rust your machine, toolholders and everything it come in contact with.

Depending on how much you cut, at night or when you are done cutting, I strongly suggest spraying everything with some oil.

[Mike S @ S4A]

The nice folks at Harvey Tool also make some special uniflute cutters...maybe worth a look

or call to their tech dept for f/s rec.

[Jim at Gentex]

John,

 

We cut polycarbonate lenses quite a bit, so my data may be a good starting place for CPVC.

 

I usually run a 1/8" high helix carbide end mill @ 2500 rpm and 40 IPM and .09 depth-of-cut. This seems to give me a good balance between speed of operation and good surface finish. Too slow on the rpm's, the cutter pushes, and too fast, the plastic melts and loads up the cutter. It's a delicate balance, but once you find it you'll be OK.

 

We also use air blast instead of water based coolant b/c we can't contaminate our lenses with any kind of oils or coolants. If you can run coolant on your CPVC, you can probably increase the rpm and sfm quite a bit because you will probably experience less melting and loading of material onto the tool.

 

HTH

[jspangler]

Hi

Thanks for all the input. I will definitely check on the oiling of the machine for rust, so far it seems to be in pretty good shape (for a 20 year old fadal, ha ha).

As for chips, MAN, this stuff FILLS the machine. I have started filtering the coolant drains, and that helps. I have to dump about 2 Barrels of chips per every 10 16" dia. parts!!

 

See Ya

John

 

PS-OLD ( I mean REALLY old!!!) fadals are a trip...