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From: stevieray re:wire feed welding
Date: 05 Jan 2001
Remote Name: 188.8.131.52
It has been a long time since I have read any of this forum. In regards to wirefeed welding of cracks we have been doing this at our mill since I introduced it 5 years ago. We initially had some problems but now have fantastic welds that all but disappear into the sawplate. We use a computorized welder with five programable presets for our various saw guages which saves a lot of time for set up, just push a button and it automatically sets for guage of steel, wire size, wire type, sheilding mix, wire speed and heat range. I labled each pre set with our saw type ie: Head saw ,5ft resaw etc, so even the trainees have no problem. I made up a 12 by by 1/2 inch copper plate with two hold down clamps on it and a heater to keep it warm. The plate is also relieved for the saw teeth just below the clamp line. We use chrome moly.035 wire and an argon/CO2 mix. The presets were set by using this info as well as Guage of plate. The computor gives its best solution for the aplication but can be modified (feed speed and voltage) to suit and then entered into the preset. When using chrome moly wire the manufacturer suggested a pre heat to 900 degrees so I heat the saw up with a torch for a few seconds or until a straw color starts to appear then I weld the crack starting on the copper plate and working inward. I then release the clamps and let the weld cool for a minute or so to make sure it is below critical temp. and the anneal it with the torch using the "shadow " method. I then let the saw cool down off the heater using ambient air temp. You don't want to force cool this weld as with any weld and letting the weld cool is the longest part of the proceedure. After the weld is cool I dress it off with a 64 grit sanding disk on a small 4 inch angle grinder. Since I start the weld on the copper plate there is a buidup in the gullet which is removed with a die grinder with a carbide burr.
As I said, this is by far the easiest way to weld cracks accuratly and even the trainees can weld like pros with very little practice time. When we first installed our6ft. horizontal twin (USNR/Letson Burpee)we had major cracking problems which turned out to be from vibration from the husk being welded to the mill during intallation. Our staff got lots of welding practice bordering on suicide at one point, but all is well now except for the occasional crack. This machine is very sensitive to dust buidup on the drive wheels ( brushes help keep this down) and dry press roll air cyliders. Keeping the airline oilers checked and maintained daily keeps this problem at bay. Better to have to much oil than not enough.
I hope this information will be of some value to you. Thanks, SR