BASED on his experience, Praxair's Lynn Meade believes most manufacturers don't know their welding costs. And when they try to cut their costs, they concentrate on paying less money for wire and gases, not realizing that the major costs in welding come on the labor side.
“I can't think of one time I've gone into an account and I couldn't actually reduce their costs by 20% without hardly spending any money,” says Meade, whose presentation at the 2002 Robotics Seminar in Iowa in November, “Productivity In Metal Fabrication,” was one of the most heavily attended. “That's amazing to me. Companies waste money and aren't able to keep up with new ways of doing things. To their credit, most are willing to look at it and work at it.”
He says that most of the large truck body and trailer manufacturers already have made significant changes in the way they operate, but that most of the medium and small companies could benefit greatly by doing it.
Meade says that according to Barckhoff & Associates, most welding operations are 20-30 years behind their sister machining operations, and productivity of the average welding operation can be improved by 20% to 40% with little or no capital investment.
He says that 85% of welding costs come in overhead and labor, with the rest in wire (6%), equipment (4%), gas (3%), and power (2%).
Welding has been affected by numerous market changes and trends: new high-strength steels, with less oxidizing shielding gas blends; stainless steels; an increasing demand for aluminum in the transportation industry; increased use of robots, laser, and fixed-automation systems because of lower cost and faster, easier use; new equipment technology (invertors, pulse power, and digital wire feeders); stricter environmental regulations; and increased economic concerns about manufacturing costs.
The most significant variables that affect costs and productivity:
Shielding gas blends.
He says shielding gases play a major role in influencing the metal transfer and should be optimized to control important characteristics. The blend has a dramatic effect on the useful range of welding parameters, and an expanded operating range allows the welder to alter the metal transfer characteristics for maximum output.
“Shielding gases are not a major cost, but they can influence a lot of things that happen during the weld,” he says. “You want to make the shielding gas as non-oxidizing as possible. You want to reduce the amount of CO2 mixed with argon because that reduces fumes and smoke and spatter. But more importantly, it allows you to get into high-speed welding processes like spray arc and pulse spray that you can't do with a high CO2 content. Twenty percent or higher starts causing problems.”
Fillet weld size.
He says controlling the weld size is a very important part of the design specification and is often overlooked. Oversized welds are often overlooked due to the rationalization that more is better. The welding wire size can contribute to oversized fillet welds. Overwelding will increase labor and overhead costs as well as waste wire and gas.
Shielding gas conservation.
He says 345,000 cubic ft of shielding gas is wasted during one year if a single 40 cfh lead exists in the distribution system — and leaks can occur anywhere in the system. He says welders typically use an excessive amount of shielding gas, thinking “if a little is good, more must be better.” He says a minimum of five cubic feet of gas is required to weld one pound of welding wire, but the industry average is 30 cubic feet.
Meade recommends using point audits, instituting welder training programs, and inspecting the integrity of the gas distribution system.
Metal-cored wires
Meade also suggests that manufacturers consider using metal-cored wires. Advantages include: deposition rates that are 20% greater than flux-cored and 30% greater than solid; deposition efficiency that is typically 97%, vs. 85% of flux-cored; quality welds over rust and mill scale; low spatter levels, as opposed to runs produced in a spray or pulse mode; little or no slap cleanup; easier to use because it's less sensitive to welding variables; all-position welding is possible using smaller diameter and/or pulse equipment; and lower fume levels because it operates like a solid wire with low fume levels.
Other areas to investigate:
Shield gas supply method.
He says cylinder to bulk supply eliminates cylinder handling labor, insures uniform gas blend, reduces regulator repair and residual loss, and improves safety.
Meade says a metal fabricator that uses 50 high-pressure cylinders per month will save over $17,000 per year in cylinder change-out labor and residue gas lost — based on $40-per-hour labor and overhead rate, 15-minute change-out time, and slightly lower gas unit costs due to bulk delivery.
Cylinder mixing system.
If an argon/CO2 cylinder blend is filled without a mixing tube and is not rolled, it will deliver an inconsistent blend, he says. That will cause inconsistency in the welding process, as well as waste shielding gas.
Training and communication.
“It's one of the most important aspects,” he says. “People have a tendency nowadays to hire just anybody off the street. Anybody can stick two pieces of metal together. But the issue is whether they know what they're doing when they do it.”
According to the University of Pennsylvania's National Center on the Educational Quality of the Work Force, a 10% increase in the average education of the workers within a business showed an 8.6% increase in output. In addition, a 10% jump in capital stock (i.e., buying a robot) resulted in only a 3.4% increase in output.
“That tells me that workers who understand what they're doing and really know the process are willing to work harder for you, do a better job for you, and get things done,” Meade says. “We find they make a lot fewer mistakes once people are educated. Your re-work goes down. One company I worked with had about a 10% reject rate on their parts. We got that down to less than 1% just by educating the guys. That meant a savings of over $60,000 a month.”
Control the variables
He says prevention is at the heart of quality: controlling and/or reducing the variables to make sure the job is done right the first time.
“We try to convince companies that if they fix problems in the work area, it has the cost of, say, one unit,” he says. “If you get farther down the line or in assembly, now your cost is a factor of 10 higher. If it gets to the customer, we say it's a factor of 100 higher, because now the customer knows you messed up.”
To illustrate his view that there are opportunities for productivity gains, he cited three case histories:
A metal fabricator was using a large-diameter flux-cored wire (E70T-1 3/32) with 100% CO2 and was experiencing a very serious welding fume problem.
A survey was completed to determine current costs, welding parameters, and productivity. After testing the new process, carefully reviewing the data, and receiving a commitment for welder training, it was recommended that the fabricator use 1/16 metal-cored wire and an 88/12 shielding gas blend (88% argon, 12% CO2).
Welding fume was reduced by more than 50%, travel speeds increased 25%, deposition efficiency improved by 15%, welding costs were reduced by 23%, and the overall savings was over $500,000 per year.
Savings was $5.69 per pound, directly due to labor/overhead. Wire and gas costs were slightly higher.
Additional benefits: There was no need to purchase fume-removal equipment, or the cost of maintaining the equipment; due to the reduced level of slag and spatter, grinding- and cleaning-related materials were minimized; cleaning of the structural before painting was also reduced, saving in preparation labor.
An equipment fabricator was using 100% CO2 in high-pressure cylinders with .045 solid wire and was concerned with the lack of productivity, cylinder-handling issues, and potential welding fume problems.
A survey was completed to determine the present base line welding costs and productivity levels. After reviewing the data, recommendations were made to increase productivity, eliminate cylinder handling, and improve the skills of the welders. The process changes were to use an 85/15 argon blend, .035 wire, pipe the welding shop, and conduct welder-training programs.
The deposition rate increased by 60%, welding fume was substantially reduced, cylinder handling was eliminated, spatter was minimized, quality improved, and there was an overall savings of $370,000 a year. Other benefits: less cleanup, less rejects and repair, and less noise in the shop due to less grinding.
An auto parts manufacturer was using solid wire with C-25 (75/25) shielding gas on 60-plus robotics cells and 20 manual cells. He wanted to increase productivity and quality, plus minimize the concern with welding fume.
A survey was done to determine the present robotic speeds, capabilities, quality and fume levels. The results were reviewed by the parts supplier, which then agreed to make the necessary changes to accomplish their goals of increased productivity, lower fume levels, and improved quality.
The recommendations were to change to an 85/15 shielding gas blend, fine-tune the parameters, increase robot speeds, and repair and modify the shielding gas distribution system.
Robotic welding speeds were increased 10% and overall productivity by 5%, fume levels were reduced by 20%, higher weld quality was achieved, shielding gas distribution system was corrected, and over $600,000 was saved in the first year.
Other benefits: less fume resulted in reducing the load on the fume removal equipment, and there was less cleanup due to less spatter.
Meade concludes that the metal fabrication industry is changing, and companies must change with it.
“Training is the key to competing in the industry,” he says. “There are numerous opportunities for improving profit. Increasing productivity, improving quality and reducing welding costs can be accomplished with little capital investment while improving the welding environment.”