The next important item on the work order is the thickness:
This is the one thing that can’t be fixed. Wrinkles can be smoothed out. Humps can be pressed out. Hard metal can be softened by annealing (a form of heat treatment). Cracks can be welded. But once the metal is thinned out, it can’t be made thicker. Well, actually, it can be. But it is a very laborious and expensive process. I’ve seen thinned-out heads overlaid with weld in the thin places, then ground down smooth to blend in with the parent metal. But that takes a lot of weld and a lot of man-hours. Ninety-nine per cent of the time if a head is thinned out it is scrapped. Or the customer is called. If I thin out a head, I take a detailed reading with a sonic device which we call a thickness checker. Don’t laugh. A screwdriver is called a screwdriver because it drives screws. I then map out the thinned-out region on paper and give it to the foreman. The customer is called and given the bad news. Most of the time, if it’s not under minimum by a lot, they’ll take it. Hell, if it is under by a lot they still might take it, depends on how quickly they need that head. If they won’t accept it, then a replacement piece is rushed through the shop, hopefully not to be thinned out again. Of course, all of the material and labor costs are eaten by Brighton. So thinning out heads is really frowned upon.
You might wonder how I can still thin out heads, considering how long I’ve worked there. I don’t do it as much as I used to, but it still happens. Every time you make a pass on a head, which means using the flanging roll to force it around the icr roll while it is spinning, in order to make the head smaller or bigger, you are thinning out the metal. You are squeezing the metal between two spinning rolls. The harder metals don’t thin out much, and you usually don’t have to worry about them. But you really have to watch the softer metals. Also, you are more likely to thin out heads formed on a sharper, or smaller, icr roll. Also, some of our customers order impossibly tight minimum thicknesses. They usually do this when they are trying to keep the weight of the head down. They want a head a certain thickness, but only weighing so much. Sometimes they do this because they are ignorant fools. They don’t have a clue what happens to metal while it is being formed into a head. So sometimes there is simply no way. Whenever I point this out to the foreman, I usually get, “Just do the best you can.”
Also, some operators, especially the newer ones, really squeeze the metal while they are forming it. I’ve got a light touch. I can wrap metal around the icr roll tightly with very little squeeze. But some operators try to smash the metal into shape. You hope over time they’ll learn to be gentler with the metal.
Sometimes heads are thinned out so badly they are totally ruined. The thin out usually occurs in the icr area. This can be cut off, and the radius, which is still plenty thick enough, is saved and used for a smaller head. Other times the smaller thinned out heads are made into fire pits. Thinned out stainless steel heads work great for this. The edge of the head is laid out flat, or turned down a little, then its polished, and legs are welded onto it. Polished stainless steel fire pits make good retirement presents. I want one when I retire. If I’ve still got this blog going when I retire, a little over a year from now, I’ll let you know if I get one. Hell, I’ll take a picture of it in my backyard and post it
There are other difficulties with the thickness of the metal besides thin-out. The thicker metals can be very difficult to bend into shape. Sometimes it takes all the pressure the machine can generate to form the head into the shape it needs to be. And thick metal loses its malleability quickly. You had better get a thick head into shape quickly, or it can become too hardened to work with. On the other hand, thin heads wrinkle easily. You have to flange thin heads more slowly with little pressure to keep the wrinkles out; otherwise you have to roll the wrinkles out, which can be laborious. But thin heads are more likely to crack if you work them too long.
These are difficulties, but not insurmountable problems. Over time you learn how different metals and different thicknesses behave while you are flanging them. It just takes time. You learn by repetition. Only there are so many different combinations of metals and thicknesses and shapes and other details that you seldom have true repetition, you are always encountering novel situations. That’s what keeps the job interesting. But it also keeps you cussing.