heat treatment opinions

[eqshop9689]

Hello,

I am new to heat treating and i have a few things to heat treat. I will send them out to a heat treat facility. How would you heat treat these items?:

A punch and die set made out of D2 tool steel.(this die set will be blanking out 1.820" round 6061 discs 3/16" thick.)

Several hand held mechanics punches made out of S7 tool steel. Used for heavy equipment brake part replacement bushings of various size and material types. The mechanic will hold these in hand and use a hammer on them.

A couple S7 punches that will go in a hand held air hammer for removing old brake bushings.

ok thanks!

Steve

 

[plastikdreams]

How would you heat treat these items?:

With a heat treating oven

 

[Luke.kerbey]

I’m not a press tool maker but I’d assume the D2 parts would need through hardening,

https://www.uddeholm.com/files/PB_Uddeholm_sverker_21_english.pdf

The link for the uddenholm sverker 21 is their version of D2 which won’t be far from what you have.

Those punch sets might need hardening like a punch, where it’s hardened and tempered back on the tip but left soft on the end that’s striked with the hammer.

And the air hammer type punches sound like they’d be fine through hardened.

You can probably google a material data sheet for s7 and make your own mind up but that’s my opinion

 

[Hazzert]

I think OP needs to be more worried about the temper than the HT.

There are charts available with temper colours, hardnesses and their general purpose applications. It might also be in the MH somewhere also.

 

[john.k]

You need to be sure the punch wont shatter or chip when hit with a hammer,and through hardening isnt it....this why punches and drifts are left soft and only the cutting edge hardened........any old machinists book will show the correct method of hardening punches and chisels for hammer work.

 

[DDoug]

Talk with the heat treat vendor.

tell them what you just wrote here.

They will give you hardness numbers, file them for the next job.

 

[Terry Z]

As stated above your heat treating shop is where you ask questions. I also have this book: Heat Treatment,Selection, and Application of Tool Steels by William E. Bryson this is my go to for information. And we have a near by shop that makes parts for many different jobs that need different hardened tool steels. I call and ask them questions too.

 

[AHUNT]

Hudson tool steels heat treating info is fantastic. They have a page for both D2 and S7. High Speed Steel | D2 Tool Steel | D2 Knife Steel IMO on the D2 you should go as hard as possible and the S7 should be as tough as possible. I'd through harden both and make sure you temper them too.

 

[AD Design]

You haven't stated whether the punch/die set will be used in a press or struck by hand. Fully hardened D-2 does not like to be struck with hammers and will chip under impact. How the punch will be located, guided, and die clearance will affect how well this works for you. If the die set is like a simple two-plate shim die for occasional use then draw back the struck end to Rc 46-48 (although 3/16 is still quite a hit by hammer). If you intend for this to make 50 at a shot a two plate set isn't a real good choice and I'd expect frequent sharpening due to mis-alignment during operation. Most punch/die applications will also have 2-3 tempering cycles but your HT'er should know this, go with what they recommend. A press is better than a hammer for this for a lot of reasons, use some kerosene too for blanking.

You also haven't described how the S-7 will be used on the bushings. Is it a driver or cutter? Do use a good size chamfer on the struck end to minimize mushrooming, which will lead to splitting. A drawing of the items involved would help. I don't think I've offered much in the way of advice. Use a press instead of a hammer for the aluminum.