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1144 "high strength" vs "ultra strength" for knurling wheel & knurling consultant?

favalex

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Mar 16, 2017
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rainy side of Oregon
1144 "high strength" vs "ultra strength" for knurling wheel & knurling consultant?

Wondered if anyone could weigh in with real experience with 1144 "high strength" vs 1144 "ultra strength" (labels from MMC) I would also like to meet a knurling or cold forming expert in the Portland, OR area.

We make inhouse a wheel for a special knurling application. The shaft is part of the wheel. The material we're knurling is 6061-T4.

Did a few last year as a prototype from the 1144 "high strength" which they say is 100,000 yield, RC 25. The "ultra strength" is supposed to be 130,000 yield and RC30. We ran about 200 "knurls" with the wheel before it broke. It did wear somewhat along the way, changing the depth and sharpness of the knurl pattern.

I'd thought I was going to do the final one from O-1 and get it hardened, but it looks like we may be doing more prototyping to fine tune the pattern we need.

My carriage is made from 4140 w/o heat treat. Shaft is integral to the wheel The shaft diameter is pretty large compared to the knurling wheel diameter.

I think we're also at the point where we could benefit from talking with an knurl or cold forming tool designer as a consultant for a few hours, if there's someone in Portland OR area I could meet up with and show them the tooling we've got. I've got a lot of specific questions, but I'm sure there's a lot of stuff I don't know I don't know as well.

Thanks,

Alex
 
Elongation in 2" tells the tale. EMJ catalog lists it for Stressproof and 1144 Hi-Stress

A paltry 7 or 8 percent

Not that this stuff would ever be considered "cutting tool" material in any case.

The poor toughness broadcast by its elongation does predict failure due to lack of toughness

For TOUGH see something as simple as 2" 4142 heat treated to 285 Bhn showing 17.5 % elongation in 2"

Mass Effect data for 4142 in thumbnail
 

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Where/how did your tool break? Was it where the integral shaft meets the working part of the knurl? If so, the inside radius there is probably too small, and that would give even proper tool steels a short lifetime. If that was the problem, you can probably 10X the tool lifetime by using a generous radius. Still, 2000 parts would not be a very long lifetime.

As johnoder says, 1144 is no kind of tool steel.

As you're in the Portland, OR, area, make yourself familiar with Pacific Machinery & Tool Steel Company. They stock a bunch of stuff, cut from plate on demand, and usually have a decent offcuts table for 4140/4142 and similar if you're in a real hurry.
 








 
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