Flame Hardening Video

[RussZHC]

So one topic of "research" today was flame hardening.

Came across this video of "hot saw" sharpening [in this reference I had not heard of it either...its not the saws used in lumberjack contests] and flame hardening. Industrial scale but somewhat interesting process.

http://vimeo.com/16803544

[lazlo]

Neat! It's a giant Foley-Belsaw

[planeman]

Anybody with an oxy-acetylene torch can do flame hardening. Here is the procedure:

If you have ever noticed, when you open the acetylene on an oxy-acetylene torch and strike a flame, a lot of carbon soot is formed. The object in flame hardening is to use this pure carbon and infuse into the surface of steel while it is red hot to produce an outer layer of carbon-hardened steel.

As oxy-acetylene welders know, you normally adjust the flow of oxygen and acetylene so the cones formed by the flame meet, keeping it a hair on the soft side. To flame harden, you set the flame so there is an excess of acetylene (very soft flame) which produces an excess of carbon in the flame, more than the amount of oxygen in the flame can react with. When the steel is heated with the torch flame the excess carbon reacts with the red hot steel surface and produces a high carbon steel surface.

Years ago I watched this being done exactly this way on a giant steel gear for an earth mover at a LeTerneau-Westinghouse manufacturing plant. The huge gear was mounted on a pivot so it could be slowly rotated by hand and a man with a large oxy-acetylene torch played the flame over each gear tooth one at a time until it was red hot and held it there for few minutes or so, then he went to the next gear tooth.

Planeman

[RussZHC]

I found it interesting since it is clearly not at the "home shop" level.

I have not deliberately undertaken such hardening (suspect done some by accident, or at least part of the procedure) but to me it looked a little wasteful to heat up a given tooth, quench it immediately only to heat up the adjacent tooth and in doing such reheating a portion of the area just heated and cooled. I know it has to be done this way, still...I always found brazing with multiple torch heads interesting as well.

There is quite a bit of info available, including this site and the place I am going to start is by increasing efficiency in terms of heat loss [bricks to retain heat as opposed to "nothing"]

[Mcgyver]

Planeman, good post, thanks for the description/explanation

[J Tiers]

Vimeo seems to be snafu....... the video stopped 5 times before it was 25 seconds in.... Had to stop and re-start it each time. I gave up

[J Tiers]

Vimeo seems to be snafu....... the video stopped 5 times before it was 25 seconds in.... Had to stop and re-start it each time. I gave up

[miker]

Short duty cycle. Have to wait until the video cools down.

Rgds