Generic 17-4-H900 vs Carpenter Project70 vs ? for tool life

TKassoc · May 1, 2019

This may be a question for the swiss guys. Compared to standard material is the Carpenter Project70 version of 17-4 H900 stainless substantially more free machining? I'm running cold finished 3/16in round stock in a b-axis mill-turn (milling/drilling only)with most of the tools in the 0.009" to 0.031" diameter range. Any other brands of material I should be looking at?

Triaged · May 1, 2019

Those are some small tools! What are the tolerances like? Can you buy annealed and age after? Shouldn't get much size change on what is likely a small part. Do you have enough RPM to get close to the right SFM range?

Carpenter has a patent on the material composition so I'm not sure other brands will change machinability much but that's just a guess. I'd like to hear if anyone has and Project 70 experience.

Dan from Oakland · May 1, 2019

We run a 304 job using Project 70 ss and its like cutting butter- no burrs, great tool life etc. I would definitely try it for your job.

FredC · May 2, 2019

I worked in a screw machine shop back in in the 70s. The owner gave a substantial discount to customers that supplied Carpenter material. We typically ran it 10% faster than the EMJ book recommendations and still got much better tool life.
Since I have had my own shop 95% of my stainless has come from Carpenter the few times I went elsewhere I regretted it.
A friend has bought some German stainless from Schmoolze or something like that and said it was comparable.
What we have run is mostly 302, 303, 304,and 416HT, not enough 17-4 to speak of, but with Carpenter's reputation on project 70 I would expect the same kind of results.

TKassoc · May 2, 2019

Thanks for all the insights. I'm going to get a bar and see how it runs...then I'll fight with getting the material substitution through with the customer.

I have 42K RPM so I can cut effectively at this size but I'm chasing features so small that the edge-hone on an endmill flute has a dramatic effect on burring. Lots of 4 and 5-axis simultaneous cuts with 0.010" endmills. Medical customers always know how to make parts expensive and hard to make

FredC · May 2, 2019

Ask Carpenter if they still do the sample paks. A few years ago they would sell you a couple feet of different sizes for trials. Their normal line item minimum is $200.00, 20 bars will cost the same as 1 bar.

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Generic 17-4-H900 vs Carpenter Project70 vs ? for tool life

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