Defining the 'welding shop'

My first experience with welding was when my dad taught me to stick weld in the basement of our home. When I was about 9 years old, he came home with a new welding hood. I remember asking him who the hood was for and being mortified when he said it was for me.

I donned the heavy, moldering leather welding jacket—complete with the stale, sweaty leather smell they all have—and clamped the claustrophobic, lightless hood over my head and, to my surprise, absolutely loved it. The funny part is I still use some of the same teaching techniques my dad used on me when I instruct welding wannabes.

Figure 1. General tolerance guidelines for welded assemblies.

I can’t remember what my first welding project was, but I was scolded because I went through a 50-lb. box of rod just running beads on a flat plate. Something about the arc, and the delight of chipping off the slag to expose the gleaming weld underneath, caught my interest. What started as a ¼ "-thick plate ended up being about 6 " thick when I finished. My friends and I used to take turns watching the electric meter speed up when the arc was struck.

I want to define what I call “the welding shop.” It encompasses all the aspects of putting together products—and ideas—that happen to be made of metal. This can range from welding thin sheet metal to heavy plate and structural work.

In addition to welding, the typical shop performs many other operations, including layout, shearing, forming, rolling, punching and cutting. You will quickly find yourself going the way of Wisconsin ice cutters if all you focus on is welding. As far as I know, robots are not yet available to run every machine in a shop, remove broken bolts and drive trucks to deliver finished goods, so your best bet is versatility. I have had the good luck of working in shops where everybody did everything, and some did certain things better than others. Pure welding can be pretty boring, but when you add the challenges of fit-up, distortion control and layout, it becomes much more interesting.

As obvious as it may sound, the first step in any fabrication job is to do a little planning. This can be as simple as looking over drawings or job information and making a cutting tool list, or as complex as designing new fixtures or specials to get the job done. A little thought goes a long way.

Always take a minute to look at the whole drawing. Be sure to examine any notes or additional processing, special materials or anything else that impacts your part of the process.

Examine the tolerances and understand the job requirements before making anything. This is particularly important when geometric tolerances are used. Check for difficult geometric relationships, such as projection zones and complex feature relations. The larger the part, the more important it is that you never assume the designer or engineer covered all the bases. Most of the time, you can count on the opposite.

If you need additional information, be sure to get your questions to the appropriate people quickly. It takes time to get specific questions answered, so ask early and in writing. Include a sketch or photocopy of the relevant section of the drawing.

Think in terms of subassemblies on complex jobs. It’s almost always easier to build and control a smaller part of a large project than the entire project at once. In addition, it’s much simpler to correct a small problem on a subassembly than to correct the same problem when it is buried and locked in the basement of a large welded fabrication. It won’t cut it to say, “Sorry, boss, I welded this aircraft carrier’s keel on backwards.”

Speak up if you see something you think might be a mistake or a potential problem. This is not an excuse to complain about every little thing you find difficult; if you cry wolf all the time, nobody will listen when there really is a problem.

You’d be surprised how many times the designer or engineer can change details in a way that causes fabrication problems. Remember, they are looking through a different lens. What looks like an obvious problem to you may have been the first solution that was thought of to another problem, and no additional thought was given—the designer or engineer simply moved on to the next hundred decisions.

Be realistic about tolerances than can be achieved with welded assemblies (Figure 1). Don’t make the mistake of trying to avoid expensive machine work by substituting even-more-expensive precision fabrication and the inherent problems that go along with it. Trying to force tighter tolerances into the welding department just results in production delays and cost increases. CTE