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Join the resistance

Resistance welding is used in a plethora of applications; getting to know the process can be a boon for welding professionals

For every car we drive, every airplane we take and a whole host of other products that we rely on in our daily lives, resistance welding plays a major role. But when compared to other types of welding, such as MIG and TIG, resistance welding seems like it’s more of a background player.

“All automobiles, most aircraft and heavy trucks as well as numerous appliances, home goods, tools, water heaters, office furniture, caskets, electronics and smartphones contain resistance welds, and really, the list could go on and on,” says Don DeCorte, vice president of RoMan Mfg. Inc., a manufacturer of water-cooled high-current, low-power resistance welding sources. “And many of those items are 100 percent resistance welded. Despite being one of the most misunderstood and underappreciated welding processes, resistance welding, ironically, is one of the most robust, proven and simple of all of the various welding processes used today.”

Because resistance welding doesn’t require additional materials to create a strong bond, the process is extremely cost effective.

Key advantages of resistance welding include strong bonds, no need for filler materials, easy monitoring and control, low overall operating costs and little to no emissions. While an arc welder must cultivate the skills to lay down a successful weld, resistance welding technicians operate equipment that produces the welds. Unlike the arc welding process, the success of a resistance weld is highly dependent on equipment design, settings, and maintenance processes and procedures.

Based on its current position on the welding totem pole, it’s safe to say that resistance welding could benefit from a public service announcement. So, with the help of the American Welding Society (AWS) and experts like DeCorte, Welding Productivity was honored to take on the task.

DeCorte started his career in Detroit in 1979 rebuilding resistance welding machines and controls. He has been with RoMan Mfg. for 25 years and is a lifetime member, counselor and past national director at large for AWS.

Process details

The AWS website defines resistance welding as “the joining of metals by applying pressure and passing current for a length of time through the metal area which is to be joined.” DeCorte defines it a bit more simply: “Resistance welding can best be described as a heat, time and pressure welding process.”

Several subcategories are found under the resistance welding umbrella, including spot and seam welding, projection welding, flash butt welding and upset welding.  While those subcategories share similar processing technology, the equipment is often specifically designed to accommodate the various applications involved. For example, in seam welding, the workpiece rolls between wheel-shaped electrodes while the weld current is applied. For projection welding, welds are localized at predetermined points via projections, embossments or intersections to focus heat at the point of contact.

Resistance welding is a staple form of joining for a range of applications, including automotive, aerospace and heavy equipment.

“From simple manually fed equipment to very sophisticated fully automatic machines, there are many levels of resistance welding equipment available,” DeCorte says. “In smaller shops, for example, operators are responsible for pulling parts at certain intervals to conduct quality tests to assure the machines are working correctly. In other cases with more sophisticated equipment, machine controllers and monitors can stop the machines and give indications that something is wrong.”

Perception problem

“I could be considered biased, but resistance welding doesn’t get much attention when you consider the entire welding industry as a whole,” DeCorte says. “Although MIG and other variations of arc welding are responsible for 98 percent of the welding in the world, resistance welding holds an important niche in the market as it can complete welds that other processes cannot.”

Because resistance welding isn’t as well known as other welding processes, finding skilled welding technicians and engineers that are trained to operate and maintain these machines is difficult.

“Many times,” DeCorte continues, “the operators and, in some cases, maintenance staff have issues identifying the true nature of a problem because so much of the process is controlled by the machines and electronic controllers that run the equipment.”

So how does one become trained in resistance welding technology and application? Unlike traditional welding courses available at vocational schools and community colleges worldwide, resistance welding education is not as prevalent or easy to find. More often than not, the only training available is from the OEMs themselves that want to ensure their new customers fully understand how to operate their new equipment.

   

The Resistance Welding Manufacturers Alliance (RWMA), a standing committee within AWS, recognized this important need and has been instrumental in developing educational programming in resistance welding.

In the know

For more than 40 years, the RWMA has offered an intensive 1.5-day Resistance Welding School that covers all aspects of resistance welding. Their Fall Resistance Welding School will be held from Nov. 11-14 at McCormick Place in Chicago. More information, including the method for registration, is available online.

Also available through AWS is an online course titled Welding Fundamentals II that focuses on the science, equipment, consumables, variables, safety precautions, and advantages and disadvantages inherent to resistance welding, plasma arc welding, electron beam welding, laser beam welding, cutting and drilling. More information is available on the AWS website.

AWS and RWMA are also pleased to introduce a new certification (and the first in resistance welding), the Certified Resistance Welding Technician (CRWT) certification, which will be offered in late 2019. This certification is targeted for skilled tradesmen, technicians and engineers that work with resistance welding in their daily jobs and want a deeper understanding of the process.

“Until now, the only real measuring stick for employers to gauge an individual’s knowledge of the resistance welding process was to ask if they had taken the RWMA welding course,” DeCorte explains. “Starting later this year, the addition of the CRWT and the fact that it will be managed and maintained in the same way that all AWS certifications are managed will allow employers to know before they hire someone that they have a specific working knowledge of the process. This is win/win for both employer and employee.”

Candidates who pass the CRWT exam will have demonstrated that they have the knowledge and skills to operate resistance welding machinery, perform weld quality checks and manufacture consistent products. Those who earn the CRWT credential may have more opportunities for career advancement and higher income.

Resistance welding is well-suited for automation, further elevating an already highly controlled and repeatable process.

“When companies are seeking high-quality individuals in the arc welding industry, they recognize the value of the AWS CWI certification and are willing to pay individuals more when they have it,” DeCorte says. “With the CRWT, the resistance welding industry will have a recognized certification that employers can use as a benchmark when hiring new operators, technicians and engineers. The RWMA school along with the addition of the CRWT certification will assure individuals have knowledge of machines, setup, testing and quality processes, all of which are directly related to resistance welding.”

In addition to the CRWT certification, AWS is also in the final review stages of the 6th edition of its Standard C1.1, Recommended Practices for Resistance Welding, as well as C1.5, the Specification for the Qualification of Resistance Welding Technicians. Both publications will be available in the AWS Bookstore later this year.

In-house efforts

In conjunction with the extensive efforts at AWS, DeCorte says that resistance welding equipment manufacturers such as RoMan Mfg. must also assume the responsibility of training welders on the equipment and products as well as the process in general.

“We have a huge need to ensure our employees understand how our product is used and how it must perform for customers,” he says. “The better our people understand the process and what key roll our product plays in the function of the equipment, the better our product will be and the better we can service and help customers.”

Even though RoMan Mfg. doesn’t make the entire resistance welding machine, it does produce special power supplies and transformers that go into the resistance welding machines and robotic welding guns that make the actual welds. The company’s parts are integral to the success of resistance welding operations and, therefore, a deep understanding of the overall process is critical for all who work there.

“Until now, we had to supply all of the training to our employees and customers,” DeCorte explains. “With the recent launch of AWS’s online training, a redesign of the RWMA resistance welding school and the new CRWT certification, we’ll be able to have more employees get both basic and advanced training.

“When I tell someone that I’m in the resistance welding industry, it comes as no surprise when they ask me what color my welding helmet is,” DeCorte muses. “Perhaps we can change that.”

American Welding Society

RoMan Mfg. Inc.

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