Work hardening... re drill and tap

P

PEI Rob

Guest
I am fairly sure it was me that caused a non-issue but here goes. I drilled and tapped several actions and one hole I believe I work hardened. I do remember drilling this hole quite easily. It dulled a tap and took some effort to complete.

Did I drill too slowly and harden it? SS Rem 700
 
Work Hardening?

It is certainly possible that work hardening occurred when you drilled the 416 stainless. It would be caused by feeding too slow, not slow spindle speed. The stainless recievers are pretty tough to tap anyhow and if the tap is even a little bit dull, it can be a problem.

Scott Roeder
 
Most metals, steel, stainless steel, even lead, aluminum and copper can and will work harden under the right conditions.

Many of the old WW II Mausers, Enfields and Springfields were a B****. Buncha' drill bits and taps were used in those days as well as CCl4 (Carbon Tetrachloride).
 
I was recently drilling and tapping some 17-4 and I discovered that if I slowed the rpm way down and kept a good feed the material did not work harden and ruin bits/taps. You want the heat to come off in the chips and not build up in the part.
 
Work Hardenning

As long as the drill is cutting, work hardenning should not be a problem. What happens in most instances is the RPM of the drill is too fast, it burns the cutting edge, starts to rub, and things go downhill from there.

Shaving build-up can introduce undue heat and cause the same problem.

Remember, the culprit in most problems such as this is excessive heat.

When drilling materials with a certain amount of toughness, (I would not consider 416 one of these), the best thing to do is drill a small way, back out, add cutting oil, and continue untill you reach the correct depth.

As with many things in machine shop work, a little common sense goes a long way...........jackie
 
Find yourself some inconel and drill some holes in it... that will teach you all you need to know about work hardening and drilling in general....and swearing too! I have experianced more of this however with cromo than 416, I've broke a reamer before from "breaking through" the work hardened skin and loading up to fast.
 
Ndh

The guy that invented Inconel should have to spend eternity machining it.

Some of the worst stuff we ever encountered was called 'Astralloy". It was a high nickel alloy that was designed to reach a high hardness level and still maintain a high degree of toughness.The manufacturer touted as a "miracle in metal'

The real miracle was trying to machine the stuff.........jackie
 
Heat makes stuff toughen up (work harden)

400 series SS will do it, but the material only goes to like 40HRC and even that is debatable sometimes so you should still be fine. Just have to ensure you use sharp tooling. We used 400 series SS on the Dakota Predator actions when I worked at Nesika. Getting the material hard enough was the initial big debate when first started prototyping. (don't let this scare anyone, they are fine. Just took some creative oven use to get there)

Inconel, Invar, D series steels, 6AL-4V Titanium and Copper Tungsten are some real "mother you know what urs" to work with sometimes.

6 years and two job shops later doing medical/nuclear/aerospace stuff taught me all I ever want to know about whittlin on that stuff.

Good luck.
 
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