If a metal fabricator has been around long enough, he probably has come across more than a couple of welding situations that have him lifting off his helmet and scratching his noggin. He likely has done everything correct according to the textbook, but the joint just does not come together like it should. Such is life with new alloys and old steel. Check out Mike Barrett's story "Beyond low-carbon steel: A basic, nontechnical discussion of welding metallurgy" to read about some of the challenges related to this type of welding.
When people talk about institutional knowledge in manufacturing, they are talking about the stuff locked up in the brains of old dudes who have all the right answers for all sorts of production puzzles, many of which are not found in books. These guys aren't about to sit down and write a "how-to" book, much less read one, so it's imperative that someone jot down this type of information for up-and-coming fabricators.
This type of information can become part of a formal work procedure that an inexperienced welder can reference if he can't figure out how to right a welding wrong. Many old-school fabricators laugh at the thought of formal quality systems and sitting in training sessions for such things, but this formal approach to sharing knowledge with all members of a shop team, not just the most experienced, keeps a company flexible enough to meet any production challenge.
The "Beyond low-carbon steel" story actually inspired this blog post because the article inspired a wonderful chain of e-mails that anyone who has handled a welding torch should read. Bernie Bisnette sent us this e-mail:
"I just wanted to throw a few points out there that may be of help to those that found the article "Beyond low-carbon steel" interesting. I work as a restoration welder/fabricator restoring trolleys—old trolleys—at the Seashore Trolley Museum in Kennebunkport, Maine. These are rusted, beat-down trolleys! My days are spent dabbling in welding witchcraft, trying to work with the old steels and joining the new to the old.
"I have found the 6013 electrode really performs. The old steel always absorbs the weldment, so favor your new steel and whip it into the old. When the old steel cools, hit it again. The old steel will sink until it is diluted with the new, and once that happens you can run normal passes.
"There are times when DCEN works better than DCEP. You just have to experiment around and watch how the steel is reacting and the amps on the power source. In some instances, I have been down to the point where the rod barely arcs. You just have to watch what is taking place. It takes a while sometimes to get it going.
"Sheet steel is another issue, and preheating can be tricky. I run turn buckles down my sheets of 10- to 16-gauge steel. This way I can turn them to stretch the welded zone. A needle gun is your best friend to peen the weld area and stress-relieve it; then it's time to start turning the buckle.
"I read that when they made these trolleys, they would prestress the steel on leveler-stretchers, so it was installed already stressed. When heat hit it, it could not stretch anymore. You have to be brave and venture in."
We also received a note from R. Daniel Carmichael of Inverness, Fla.: "Anyway, about welding cast iron … two things that my master taught me a long time ago:
- Never weld on ground cast iron. As you know, the high carbon content, upon cooling, precipitates out of the solution as graphite flakes. When you grind on it, you smear the graphite, and when you weld, you are setting yourself up for failure. Always use a clean, sharp file and file the area you are going to weld.
- Never preheat cast iron unless you can preheat the entire casting. If you can't, then keep it as cool as possible, welding only a few inches and allowing it to cool until you can touch it with your bare hand. This may take a while, but you will be successful."
That's advice that won't be shared in any introductory welding course. Be sure and grab the ear of some of these veteran welders before they walk out the door. When they leave, more than their truck will be gone from the shop.