National Vaccuum is a client that doesn't like welding from Eagle Precision.
Well you can't really look at the casting after the fact and tell if it's done right or not. When you're welding you have to know what you're doing. If something failed Mag particle inspection and it has a crack, you have to excavate that crack out 100% because if you don't and you weld it up, when it goes back through heat treat, even if it's a 10 thousands hairline crack that crack will actually grow and come right back.
Some materials act a little differently. Some that are softer it isn't as bad, but others that are harder and get a water quench it can be catastrophic.
You have to make sure the first layer of the weld gets completely filled in. That means you have to have enough heat and filler rod so that the bottom gets completely filled in with no defects whatsoever. That first weld is key. After that it's just filling it in, making sure the edges are fused of the hole. Making sure you have enough heat to melt the material together so there's no defects in it, no pinholes. You have to make sure your Argon is set properly so you don't get any gas holes in it. With carbon steels you have to make sure you get it cleaned out really well because if any carbon is left you can get porosity. It would gas out.
If you have just a cosmetic defect, like if the casting doesn't fill out properly or if you have a sand inclusion. Depending on how much sand is in it, you can just burn the sand out but it's about 50/50 that you might have to excavate the sand out and fill it up. You evaluate each part to see what you have to do. They're all different. The only ones that are consistent are ones with cracks, like if there's a corner or a really thick or thin part of a casting that gets a crack. Cosmetic stuff is sporadic and you treat it one by one.
When working with companies we get the parts in and we evaluate what the defects are. We choose how to fix them based on the requirements. The customer may have requirements. They may say "we have one area that can't be welded." We evaluate it and decide what to do to fix it. If it's a machined area we need to make sure we get the defect out enough so that when they machine it it doesn't show. After the weld they give it back welded and ground. They grind welds off so it's flush to the casting. It's a hand grinding process.
TIG welding: everything is controlled by foot pedal. Filler rod is in one hand and torch is in the other. The person has to judge as they're welding how much heat they need to get a proper weld and how much filler rod they need to get a proper weld. Some materials you have to use low heat and a lot of filler because it's so crack prone, like cast iron. Other materials like commercial grade carbon steel. They have 8620 or 8630 or WCB which is really user friendly when it comes to welding, it's not crack prone. Harder materials you have to watch the heat. If you use too much heat and not enough filler you'll get a crack down the middle of your weld. It's up to the operator to know how much heat and how much filler to use in each case.
I would say to a someone who doesn't want welding, if you run a welded casting through your testing. Some places test strength or bending. Put it through the normal tests and it will last just as long. We've seeen where people send parts to less expensive welding companies. They have approved weldings before but they failed. It could be the equipment isn't powerful enough to repair the defect, or the operator isn't experienced enough to know what the difference is.
Production welding is repetitive, as in welding two castings together. SFSA is masking the fact that it's a repair. It's very common, but production welding is repetitive. It's common, but production welding is different. It is repetitive. SFSA is sugarcoating it. Really, repairing a casting and the defects: as long as the operator is knowledgable and they know what they're doing, you're going to have a good casting.
You can't train a guy who's never welded a casting in a week to be able to fix structural repairs. Cosmetic issues, maybe. We here, all of us are trained. All the guys they have welding have been trained by father or son and they've all been doing it many years. You can train a guy for two or three years and he'll still come across something he can't fix. We tell them this is how they need to fix this casting and they do it. They don't cut corners. When we're training a guy we put him on easy stuff for a while until they get the idea or the feel of it. When they get something new that's more difficult the more experienced welders will work with it. The problem is if a defect has to be excavated out you have to know the guy is going to do it properly after you show him. Some guys get lazy and just want to get them done. You have to be confident in your guy that he'll fix it properly.