Gravity makes welding more expensive, it’s a fact… That is why downhand welding costs less than vertical or overhead welding. It’s all about deposition rates. When welding in the vertical or overhead position, the higher your metal deposition rate, the more likely the weld metal is to sag and run out of the joint. To combat these problems try using a pulsed power source that produces less heat, or use current and voltage settings that reduce the burn-off rate or use smaller diameter electrodes with good out of position characteristics. All of these solutions require a skilled welder.
Another disadvantage is that deposition rates are lower, therefore production costs are higher, not to mention the cost of a skilled welder and the ability to find one! Every solution to out of position welding problems has the same disadvantage – deposition rates are lower, and your production costs are higher. They often are much higher.
Predicting Deposition Rates
The following is a rule of thumb guideline to predict deposition rates. In the vertical position a welder should be able to weld approximately 3 pounds per hour with a stick electrode when welding. Unfortunately even a good welder welds only about 25% of the time. The rest of his time is spent changing electrodes, chipping slag and positioning. The actual deposition rate will then be about ? lb per hour. Downhand, the same welder should be able to weld 10 to 15 lbs. per hour, when he is welding.
By replacing the stick electrode with flux core wire or submerged arc, weld downhand and your welder should double his output to 30 lbs per hour. That’s also when he is welding. Using semi automatic welding equipment, your welder can weld a heavy work piece from 50% to 75% of the time, actual arc-on time. He’s then only giving you 15 to 20 lbs. per hour of weld per man hour worked in the down hand position. Using semi automatic power sources designed for overhead welding, a welder can weld about 1/8th of what he can deliver in the down hand position.
In Position Welding Can Provide a Payback
While change in welding process has a positive impact on welding costs in position versus out of position welding, the major cost savings is generated by moving the weld into position far outweigh the benefits of process changes. The savings offered by in position welding are often large enough to provide a payback of the positioning investment in less than one year.
Positioning Equipment Reduces Materials-Handling Risks
By mechanizing the weld system using the proper positioning equipment and multi wire welding, expect 60 lb. weld deposition per hour. There are several reasons for using positioning equipment. Operator fatigue is a factor in lost productivity and reduced weld quality. Safety is another important factor. Any time that a work piece is manually handled, accidents can occur. Positioning equipment reduces materials-handling risks because the work is handled one time to load and only once more to unload it.
Positioning creates better weld quality. If the weld metal is all down hand, gravity helps the weld. The result is equal legs on fillet welds, a smoother bead surface, minimum cleanup and less weld-repair time, and often a reduction in weld defects.
Effective Use of Available Floor Space
Positioning equipment also makes more effective use of available floor space. A positioner under the weldment will shrink the total space required to handle the work. For example, a weldment cannot be turned over 180 degrees without setting it on the floor and re-hooking it to a crane. A positioner can do that in about half of the space.
Positioning equipment should be considered a cost savings due to improved safety, weld quality, better floor space utilization, possibly a lower welder skill level requirement. But most importantly a positioner can reduce your cost per pound of weld metal deposited by moving your welding into a down hand position.
SOHO WELDING can custom design systems to increase your deposition rates by using new and used welding equipment. The company’s experienced staff can help you size your positioning equipment. “Call us, we know welding”