What steel to use?

I know about CRS, O-1 and D-2 that I have used for years. I have an application to make a part that will be 6" long, 1" high and 3/4" thick. The part will hold a carbide that will cut 3 pcs. .115x.017" tempered flat wire. The part will be cam driven on one end and pivot with a 3/4" shaft in the middle on Timken bearings. The area around the shaft is bigger. Imagine a rocking action. The cam is twice the distance from the pivot as the carbide so a 2 to 1 ratio. I wonder what steel to use to make the part from that will be super strong and stiff yet still be able to machine the part. Should it be tool steel and hardened? Or some cryptic alloy number? The cam is a bearing running in eccentric so a wear surface isn't critical. The last version I made of this was CRS and that was a mistake in the long run, too much deflection and deformation, the carbide pushed it around like wet clay and the 3/4" shaft wowed the bore at the pivot even though it was shrunk fit and taper pinned. I did get over 3 million operations from it though.

Reply to
Tom Gardner
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Tom, Try S-7. It's an air hardening tool steel that has terrific impact resistance and strenght properties. It also is very stable during the HT process. You see it a lot in coining applications. The only caution is that the optimal hardness band is very narrow 56-58Rc. It's easy to hit the range required but the physicals on either side fall off very quickly.

Reply to
John R. Carroll

Tom I would suggest a piece of 4340 hsr(hardened and stress releived). It comes in at around 28-32 Rc in this state but can be hardened up to

45-50 for best results. Even as is it should be far superior to CR

Tom Gardner wrote:

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machineman

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David Billington

"Tom Gardner" wrote in news:ZiEWe.1627$ snipped-for-privacy@newssvr19.news.prodigy.com:

You really don't want anything super hard, as this will lead to cracking and sudden failure (breakage) in an impact situation (cutting). In this instance, I would probably recommend a good H13 with core hardness in the

50-53 HRC range, laser hardened to 90-92 HRC. This gives you a very hard wear surface, with a tough center that will prevent deformation around the bearing, but will not fracture very easily.

Just a thought.

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Anthony

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R. Zimmerman

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