Page 32 - MetalForming January/February 2022

Fabrication: Resistance-Welding Training
conducted Knapheide’s two-day train- ing program and also helped develop the CRWT training course.
“I’m the voice of the common per- son in the plant,” says Michelena, who has more than 20 years of experience. “The CRWT isn’t an engineering cer- tificate. Rather, it must be useful for the person on the floor.”
CRWT training-course objectives:
• Develop knowledge of RW process fundamentals and physics.
• Develop an understanding of all RW process variations.
• Develop an understanding of the various machine types, tooling and basic weld-control functions.
• Develop knowledge related to RW of various materials.
• Develop an understanding of RW production-related issues and how to solve them.
• Communicate, understand and comply with RW specifications and how to perform the correct test procedures.
“We didn’t create the CRWT training
just to allow operators to pass the test; the class doesn’t give you the answers,” emphasizes Michelena. “The CRWT training provides the background need- ed to enable employees to figure out the answers, which is what they’re going to need to do on the job.”
Problem-Solving Confidence
“One benefit of training is that, when we walk up to a machine now, we have more confidence in our ability to solve issues,” says Murry. “The oper- ators see that we’re not just throwing darts in the wind, and that gives them confidence. It really sets our team apart and sells our internal training program on the shop floor.”
As an example, one product manu- factured on the plant floor requires spot welding a backplate to a stake. For years, the company fought expul- sion—the forceful ejection of molten metal, which reduces weld strength and even can create a through-hole. During training, the welding team learned how creating weld schedules with more slope (ramping up weld energy over time from the beginning of the weld) can affect the results.
“Adding slope made the sheet metal more malleable, which closed the gap between the backplate and the stake before applying full welding power,” says Murry. “We understood part of the prob- lem, but didn’t have a full enough under- standing to fix it. Now we do, and we have since largely eliminated expulsion.”
For his part, Sparrow says that dur- ing the seminar training he learned a lot about electrodes and the effects of changing electrode shanks and caps.
“The face diameter of the electrode cap can dictate where the majority of the resistance occurs within the parts,”
he says. “We learned how to control the level of reinforcement by using smaller or larger caps, which has made us more successful.”
In another instance, a machine had been set up to run a particular product but experienced problems after switch- ing to a different product and associ- ated weld schedule.
“After hours of failure, we finally start- ed to think outside of the box,” says Sparrow. “We recalled the lesson about spot-weld cap profiles, so we changed caps to a different style. Now we’re able to use the same electrode combination for every product the machine runs and create uniform welds.”
Planning for Success
“CRWT training must be driven from the top down,” says Michelena. “Busi- ness owners should consider what mat- ters most. The investment in the train- ing pales in comparison to the cost of delivering perfection with less down- time while retaining good customers.”
Cost for the in-person CRWT semi- nar and exam is $855 for AWS members and $1140 for non-members. In addi- tion, companies should consider the costs associated with study time.
“Most of the employees on the weld- ing team are Certified Welding Inspectors and Certified Welding Educators, and now we want them to have that CRWT,” says Murry. “Certification is so important to us that we’ve we set aside 2 hr. during each workday to allow them to study.”
Sparrow believes that learning is a pay-it-forward activity. “What I teach somebody today may be something that they teach somebody down the road. It spreads knowledge. While we’re helping our company, we’re also improv- ing the whole industry.” MF
On the manufacturing plant floor at Knapheide: spot welding a truck-body door assembly using a Tecna TE300 microprocessor-based welding control unit developed for suspended RW guns.
Informative Reading Helps Prepare for the CRWT Exam
Among the publications students review prior to taking the exam:
• AWS C1.1M/C1.1:2019—Recommended Practices for Resistance Welding
• RWMA—Resistance Welding Manual
• AWS Resistance Welding Pocket Handbook
• ANSI Z49.1.2012—Safety in Welding, Cutting, and Allied Processes
• A2.4-2-12—Standard Symbols for Welding, Brazing, and Nondestructive Examination • AWS C1.5—Specification for the Qualification of Resistance Welding Technicians
30 MetalForming/January-February 2022 www.metalformingmagazine.com