Machining PEEK. How bad can this be?

wrustle · Jun 17, 2015

Have a job in house working on some PEEK (Polyether ether ketone) plastic.

Here's your truly with a .500" thick sheet 12" x 12".

This one sheet will be cut up in our saw in to approx. 88 blanks that will get machined in our Haas VF-2SS sitting behind me.

What the parts are for, I have no clue, but they are costly little buggers, that I can tell you!

This one sheet of plastic right here in my hands costs.............

Just a tad over $507.00

Measure twice, cut once.............BULLSHIT.............check, double check.........and CHECK AGAIN!!!

How much fun am I in for?

I am being told to cut this with aluminum specific tooling but use feeds and speeds for steel.

Any experts out there care to weigh in on this subject?

Parts finish up at .280 thick x .500" wide by 2.5" long. Three milled bosses along the top of the .500" width, so it's basically going to look like a memory stick with three equally spaced chimneys sticking up.

Clear as mud? I thought so...........

To be continued........................

But not too long fella's.......trust me.

vettedude · Jun 17, 2015

wrustle said:
Have a job in house working on some PEEK (Polyether ether ketone) plastic.

Here's your truly with a .500" thick sheet 12" x 12".

Cut with coolant and VERY sharp tools. If it is not filled it should be easy. We use PCD on virgin peek just because it stays sharp forever and comes very sharp. The peek will never really turn into chips, you typically are going to be dealing with strings.

We turn between 250-2000 SFPM depending on the parts. being that is is virgin and tool wear is negligible the feeds and speeds will depend on the following factors.

1. is it melting - turn it down (Also chip buildup is not good and will cause it to melt)
2. am i vibrating - adjust accordingly (Peek is very stiff and will vibrate quite easily)
3. is cycle time important, go until you run into a problem with one of the others

Also, that is likely compression molded, hopefully you got it from a reputable supplier, or it can be INCREDIBLY brittle.

be ready to stop your spindle often to clear chips, also the vacuum is your friend.

rwbaldwin · Jun 17, 2015

PEEK is a thermoplastic and can be annealed, so you need to keep the tool cool. Don't get too greedy with DOC.

You need the right tool to ensure the chips fly. Sharp cutting edges, +ve rake/relief angles and polished/coated flanks so the chips don't stick. We use diamond tooling.

dstryr · Jun 17, 2015

Run lots of peek and its easy. Just use aluminum tooling (new) and machine it like delrin. Very stable.

moonlight machine · Jun 17, 2015

Easy, razor sharp polished tools. Don't let it melt. A quiet shop vac is your friend.

vettedude · Jun 17, 2015

moonlight machine said:
Easy, razor sharp polished tools. Don't let it melt. A quiet shop vac is your friend.

https://www.ridgid.com/us/en/14-gallon-high-performance-wet-dry-vac

The SNR on these makes a HUGE difference!

moonlight machine · Jun 17, 2015

Those vacs are very quiet, I built an air flow bench with 3 of them, they really move some air as well.

Krovvax · Jun 17, 2015

dstryr said:
Run lots of peek and its easy. Just use aluminum tooling (new) and machine it like delrin. Very stable.

Totally agree with that. Milling virgin peej is just like acetal. Use alu specific endmill spin to the max rpm avoid slotting has most has possible to not have heat issue and melting chip behind your tool and voila.

On the lathe the worst thing that can happen is chips getting around your tool and melt on the aurface i usually just machine it like uhmw stringy material that wont break a chip and melt easily.

btm · Jun 17, 2015

I've machined this a few times, but never in large quantities. It machined similar to delrin. I used new, solid carbide endmills (no coating) and the finish turned out great.

btm

scadvice · Jun 17, 2015

I like machining PEEK you just need to know a few rules. Climb mill, leave .015 thou. or so to finish. Avoid breaking through on an edge. Rough machine both edges and break through in the center ( with a .015 or so left on the floor for cleanup with sharp finish tool. Sharp carbide uncoated. Oh ya, coolants... most I used have been ok, but we have always washed them in stuff like Dove dish washing soap.

BTW - Glass filled will warp some. leave a goodly amount of material for finishing. Linen filled seems to not be a problem. Glass filled I used a vacuum not coolant.

I always proof out the part with delrin.

It taps OK but you may want to go with an little over sized tap and adjust your drill for minor diameter.

BillT · Jun 17, 2015

I used to machine it years back. We used it as a tiny chassis inside heart pacemakers (very small parts). Apparently it's a good material to laser weld inside as it actually withstands the heat from the welding process. Like the others said, sharp carbide works fine. Btw, the price is about the same as when I machined it back in the early 90's.

chip_maker · Jun 18, 2015

wrustle said:
This one sheet of plastic right here in my hands costs.............

Just a tad over $507.00

I take it you haven't worked with Vespel or Torlon yet

.

wheelieking71 · Jun 18, 2015

chip_maker said:
I take it you haven't worked with Vespel or Torlon yet.

I was going to bring up Vespel, but you beat me to it! LOL :eek:

First time I worked with it I was told "if you scrap this you are fired!"
I did not have a history of scrapping parts, and he was serious.

Professional Plastics says a .500x10x10 sheet of Vespel is worth $3280.00

chip_maker · Jun 18, 2015

wheelieking71 said:
I was going to bring up Vespel, but you beat me to it! LOL

First time I worked with it I was told "if you scrap this you are fired!"
I did not have a history of scrapping parts, and he was serious.

Professional Plastics says a .500x10x10 sheet of Vespel is worth $3280.00

There was definitely some anxiety involved the first time I worked with it too. Luckily the parts weren't super complicated.

Like Wruss said above triple check!

Too bad the chips aren't worth anything!

I could be damn near retired now lol!

specfab · Jun 18, 2015

moonlight machine said:
Those vacs are very quiet, I built an air flow bench with 3 of them, they really move some air as well.

Not to hijack thread, but -- are these vacs better noise-wise than previous models of Ridgid shop vacs? I have one that I can't stand running because of the high-freq noise components.

Regarding the PEEK machining: Sounds like you have a nice project there. My last purchase of 1/2" x 12 x 12 was about $460/plate in groups of 10. At least there's nothing on your drawing that states "do NOT use metallic cutting tools", as the semiconductor mfg folks like to say...

dstryr · Jun 18, 2015

chip_maker said:
There was definitely some anxiety involved the first time I worked with it too. Luckily the parts weren't super complicated.

Like Wruss said above triple check!

Too bad the chips aren't worth anything!

I could be damn near retired now lol!

You are telling me. I throw away a lot of peek chips. Prob a 100-150 gallons a month or so making tiny parts.

Speedy2222 · Jun 18, 2015

Machined it before, of all the plastics i have turned it really holds size the best, or really is alot more predictable IMO. Aluminum or plastic ( if you have the rpm) cutters work best, I have seen it cut dry and wet depending on application. Havn't messed with it in a few years luckily.

doug925 · Jun 18, 2015

chip_maker said:
I take it you haven't worked with Vespel or Torlon yet.

Torlon and Vespel SUCK!!!!!!!!!!!!!!!!!!!!!!!

Peek is easy, but it doesn't chip, per se'.
It is stringy, but with aluminum cutters (high positive, high rake, razor sharp) you should be okay.

It does move around a little, but part depending can be predicted, and moderated.

Just don't scrap too much of it! LOL

I had a run of 25 parts that were Ø1.25" x 6" long that were scrapped due to an internal Ø.375 x .09 seal groove, about 5/16 down a a 1/4" hole.
There was some melt which degraded the surface finish beyond repair or rework.
I was NOT HAPPY that day, to say the least!

Doug.

ipmmiller · Jun 18, 2015

wheelieking71 said:
I was going to bring up Vespel, but you beat me to it! LOL

First time I worked with it I was told "if you scrap this you are fired!"
I did not have a history of scrapping parts, and he was serious.

Professional Plastics says a .500x10x10 sheet of Vespel is worth $3280.00

anyone have a youtube link on MAKING Vespel ? :drool5:

...hmmm....maybe just a few stickers will do :scratchchin:

wrustle · Jun 18, 2015

Well, ran these parts today, and have to tell you......everything came out perfect......so far that is.

Parts held size without issue. No chipping or broken edges. No worn out tooling, and not a problem with chip control at all.

Approached the job using variable flute carbide end mills, and aluminum specific face milling inserts.

Here's some pics of the parts after the 1st op has been completed.

I used my Walter Valenite 2.00" face mill with Walter aluminum specific inserts to clean the top surface, then using some Lakeshore Carbide Variable 3 Flute Carbide End Mills we profiled and finished all the boss diameters, and again with a Lakeshore .125" carbide chamfer mill chamfered the parts complete.

Walter Valenite 2.00" Face Mill 9550 RPM 150 IPM .06" DOC .500" WOC (width of blank)
Lakeshore Carbide .500" Variable 3 Flute End Mill 12,000 RPM 90 IPM - Profile .300" DOC .125" WOC
Lakeshore Carbide .375" Variable 3 Flute End Mill 12,000 RPM 90 IPM - Rough and Finish the three bosses. .142" DOC UP TO .375" WOC
Lakeshore Carbide .125" Chamfer Mill 4 Flute 12,000 RPM 100 IPM Chamfer complete .010" X 45*

As I said, chip control was a non-issue!

The tool in pocket 19 (.500" dia. variable 3 flute) did the trick along with its .375" dia. counterpart. The face mill shown is the Walter 3" version of the 2" Walter face mill I used. The inserts shown are the same however, razor sharp edges and make quick work at low torque of any job!!

Sorry folks......too busy to get any video.............

Best Regards,
Russ

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