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440C Stainless Problem

We are having a problem drilling some 440C stainless steel. Anyway we are drilling 1/8" holes 1/4" deep. We have been using high speed steel and been averaging around 75 holes per operation before the drill bit needed to be changed. However now we are lucky to get 2 or 5 holes before the drill bit needs to be changed. We had a cobalt drill and tried it with the same problems. We checked for hardness which we got Rockwell 35. Which was wierd So we tried file test which was 55-60. I am thinking that it might be a chromium issue but not sure.

Does anyone have any suggestions on what I might try or what might be the problem and how I might fix it?

Any suggestion will be helpful!

Reply to
Chopster
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ask over on alt.machines.cnc.

They will be able to give you chapter and verse. Btw..there are some point angle geometries which will help out a lot. And split point is de regure for production 440c

Gunner

Rule #35 "That which does not kill you, has made a huge tactical error"

Reply to
Gunner

How many parts total are you doing?

Are you using liquid coolant? Try tunning around 1500 RPM or less and use coolant. Coolant with stainless is an absolute must in most cases. Did I mention coolant? Even cheap motor oil will help quite a bit. Just use some no mater what. Each revolution should be around .002" feed and the thrust around 100 lbs to accomplish this if you don't have an auto feed or programmable system.

If you are doing this already and your RPMs are at least 1500 or less, then there may be a different problem but we need more info to diagnose. 1500 is the maximum RPM I'd suggest to a customer without coolant.

With coolant and a low enough RPM rate, you should get 1000 holes per bit. :)

Free drill RPM and feed chart here:

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Regards, Joe Agro, Jr.
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V8013

My eBay:

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Reply to
Joe

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Tim Killian

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