Best machined Surface Finish for PEEK

[kalitri]

Hello,

I'm wondering what the best possible machined surface finish for PEEK is. The part is a small water resevoir, which will have the cavity milled out. At present the prototype is rough machined, with mill lines still visible, which disturbes the flow of water over the area. Basicall, how smooth can I go with PEEK.

Any suggestions will be much appricated.

Kalitri

 

[rnd2]

Sounds like the cutting tip radius needs to be increased or, forward thrust reduced. Either, or a combination thereof should avoid the grooving currently experienced.

 

[kalitri]

Thank you for your answer rnd2, but I need to know what surface finish call out i need to put on the machining drawing, for a smooth finish in PEEK. I won't be doing the machining myself...

 

[rnd2]

Then it is up to you to state the required surface finish and up to the machinist to tell you what is involved to achieve it.

 

[patprimmer]

I agree with rnd2

You need to know what you want, what you need, and what you have, how big the differences are and whether you can improve and at what cost to what extent.

You need to discuss this with your machinist, and possibly several others, then decide what you need re cost benefit.

Regards

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[jbel]

We have turned many small PEEK parts on a lathe (i.e. from quarter to dime size) and have been able to get fininshes on the order of 16 Ra. in the machine. We use high positive rake cutting inserts designed for aluminum and have had great results. Keep the tool nose radius as large as possible and you should not have many problems.

Milling this stuff should not be much different. Just be sure the machining house is using correct cutting parameters.

Hand finishing could bring that down to at least 16 Ra if you are willing to pay for it.

 

[PerBear]

I have specified Ra 0,2 um on some PEEK sealing surfaces. This is not achieavable by milling, only by polishing. This is a time-consuming operation that could increase cost a lot. You could also try heat treatment using the same 'lighter trick' normally used on scratched CDs, but PEEK has a much higher melting temperature making this difficult.

Optionally, you may coat or make a liner that has a better wetability than PEEK.