Home Forums Hunting & Shooting Ask The Gunwriters Tumbling brass hardens it?

I was told today that tumbling brass will harden it. I know brass will work harden, but I don't believe that tumbling it in media will. Could you shed some light on that?

Thank you,


KB

False. The metal has to be moved (displace from one place to another in the part) to work harden. Cymbals are work hardened by hammering as can be seen in the dimples. Tumbling in media doesn't move the metal.

I know several knowledgeable shooters that swear that rotary tumbling with stainless steel pins work hardens the brass.

I have not found this to be the case myself but the theory remains very imbedded among some in the longrange crowd.

False. It will not harden in a tumbler.

My understanding is that technically speaking it does but the depth of the hardened zone is so thin it's irrelevant in the grand scheme of things...

I don't claim to know absolutely that tumbling brass can or cannot effect work-hardening on it, or the degree to which it may do so. I did my tool and die apprenticeship in the old-fashioned type of manufacturing facility where they did everything in-house, design, engineering and manufacturing. And in the manufacturing, raw materials came in and finished products went out. As apprentices, we were expected to be familiar with everything done in that plant. There were a couple of engineering people whose entire job the development of various tumbling processes that could effect mechanical change on manufactured parts way beyond simple cleaning and polishing. It was a long time ago, but I seem to recall some tumbling processes for stress-relief and I think I remember some that were intended to surface harden parts. I'm thinking that some parts were tumbled in taconite pellets for that purpose and/or some sort of ceramic beads. I know various sizes of steel pins were used for some purposes also.

I've been around long enough to realize that I don't know enough about everything to make definitive statements that something can't be done.

Shot peening has been used in manufacturing for centuries, especially in the aircraft and automotive manufacturing of parts. Both for stress relieving and to install a hardened surface and while similar to sandblasting its purpose is not for the removal of material.

Phil