Arc Welding 101: Advice for quoting weldments
Q: I am looking for some insight on the best approach, best practices, and industry standards for quoting weldments. There seems to be a great deal of information out there about deposition rates and travel speeds, but not a lot about the additional variables like clamping, part handling, cleaning, grinding, and packaging. Any insight you can provide is greatly appreciated.
A: Before quoting any job, you need to determine a couple of things, mainly your arc-on time and cycle time. Following are arc-on time guidelines I have developed for quoting purposes:
- 20 percent arc-on time –Occurs in a typical manual workcell that assembles, tacks, and welds parts.
- 40 percent arc-on time –Occurs in a typical manual workcell that receives a tacked assembly and finish-welds it.
- 60 percent arc-on time –Occurs in a manual workcell where the welder rarely moves, doesn’t add parts, and is continuously welding. Also may occur in a robotic workcell that welds many short (less than 4 in.) welds with lots of arm movement and touch sensing.
- 80 percent arc-on time –Occurs in a robotic or automated workcell that completes continuous or multipass welds and does little touch sensing.
When estimating inches of weld to be laid, figure fillet welds 1/4 in. and shorter will be single-pass welds. Welds bigger than that should be calculated as three-pass welds, or weld length multiplied by 3.
These guidelines you establish for yourself are important. Get them wrong and you’ll never make money, and that’s why we’re here—to make money and keep folks employed.
I once had an employer that calculated weld cost simply by knowing how many inches of welds the weldment would require. The estimates were very accurate, but a system like that would take years to develop… and theirs did.
My advice is to apply these rules of thumb and find yourself a good weld calculator program that you are comfortable with. I’m not big on reinventing the wheel.
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