Material question

[gcode]

We have some little mushroom pins,

1.38 long x Ø.625 full radius head with .316 ± .001 shank that are part of the tool carosel

for one of our VTL. We need to build 50 of them and the machine tool repair people say they want them

heat treated to RC 68.

These parts take a beating and I'm thinking they will shatter like glass at RC68

IMO they should be built of tool steel and case hardened to RC68 so they are hard

on the outside and tough on the inside.

 

Thoughts and opinions are welcome

as are suggestion for what kind of steel to build them from

[cncchipmaker]

I used to work for Honeywell Engines and Systems and made gears from 9310 series steel and case hardened in certain areas like the bearing journals and gear teeth. These parts were designed to be tough and durable at high speeds. Maybe this would work for your application.

[Chris Rizzo]

68! My shade-tree engineering sense would agree with you Tom. Thru-hardening I'd think would turn them into grenades. What are they going into? Might you want the pins to wear/shear, as compared to the larger component they go into? 68 THRU would pretty much guarantee destruction of the receiving components upon failure. I've broken a lot of machines, motors, and transmissions, and want small parts to fail to save the big ones.

 

Since you have to make 50, assuming they are being made on an NC lathe, might as well make 100. So when the grenades fly, you still have 50 and can just case hardened those. Sorry I don't have any steel recommendations. S7? That will get you to 61ish max, but the toughness too.

 

hth

[gcode]

I think they are some kind of detent pin to provide a positive index on the tool carosel

I think I'll but by a length of O1 from McMaster Carr and get them case hardened

[mkd]

O1 has carbon throughout so the only way to get a hard case would be flame or induction hardening.

as the name implies the quench medium is oil. i have seen a flame ring over oil tank with the part been lowered through the flame and into the oil at a controlled rate.

for induction or flame hardening i wonder if Air cooling steel might be an easier choice to deal with because they cool in air. I personally would talk to a heat treat shop before i went down this road, as I've had some part failures trying to H.T. A2 with a blowtorch. (may have had to do with not enough time at temperature to make the transition).

 

CNCChip.. is prolly on a great path. 8620 would also be a great choice and both will require a carborizing step prior to hardening. you will need to specify desired case depth (prolly well under .10"). Either with induction or oven heating, this method will guarantee a tough, resilient core no matter what indiscretions happen at the heat treating facility.

Edited September 16, 2013 by mkd

[K2csq7]

Gcode,

I used to make stuff out of this.

Check it out.... customer was REALLY impressed and it sounds similar to your application

http://www.steelforge.com/literature/metal-tidbits/nitralloy/