Welding a Permanent Magnet Roller

Q: We recently had a gearbox problem on a can densifier where the main 1" diameter, 5' long shaft was bent. This shaft was part of a roller for the conveyor and this roller was "permanent magnetic". When we attempted to weld the new shaft onto the roller as the original one had been, we could establish a weld, but we got all kinds of splatter. We tried reverse polarity, different types of rods, MIG welding, and even wrapping the roller with the output leads from another welder to see if this would help. nothing we did would solve our problem. Do you have any suggestions?

A: Welding steel that is influenced by a magnetic field will challenge even the best welder’s skills. I know of no way to completely eliminate this magnetic field; however, there are a few things you can do to minimize this problem:

The first and easiest way is to weld this shaft with the SMAW (stick) process with AC polarity and use an AC welding rod.

Secondly, attach the work clamp as close as possible to the welding joint. Use good judgment to not do damage or overheat the clamp.

My third attempt would be to minimize the welding current and reduce the diameter of the welding rod. This will require welding the project with an increased number of passes.

My last try would be to tightly wrap the shaft to be welded with the work cable. Keep the wraps tight and use a clockwise rotation, the more wraps you put on, the stronger the magnetic field you will generate. The magnetic field you create by wrapping the work cable should generate a counter magnetic force which will hopefully reduce your welding problem. If the magnetic field problem increases, wrap the shaft to be welded using a counter clockwise rotation.