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March 1, 1997

7 Min Read
Microwelding: Finding a secure role with toolmakers

At first glance, to watch Phil Smith at work, you probably wouldn't guess he's a welder. He sits at a bench in his shop with a blue work shirt buttoned up to the collar. He's peering through a microscope at an 8-inch lifter; in one hand is a long, thin metal rod. His foot is poised over a black pedal on the floor, and when he presses the pedal the small gun-shaped welder in his right hand emits sparks and hisses, melting a few thousandths of an inch of the metal rod onto the lifter.

This is not ordinary welding. It's microwelding, and for more and more toolmakers and molders it's the difference between spending $100 on a mold repair and spending $10,000 or more on a new mold. Toolmakers who may have viewed suspiciously the healing powers of microwelding in the past are discovering that technological improvements in the welding industry now make small repairs and engineering changes affordable, easy, and reliable.

Smith, a former toolmaker, is the owner of Precision Micro-Welding Inc. in Boulder, CO, where he spends most of his time with his welder making engineering changes and repairing damage to molds caused by normal wear and tear, stuck parts, and errant screwdrivers. The close work and detail forces him to use a 10X to 40X microscope to keep an eye on the weld, often measured in thousandths of an inch. With welding rods measuring from .005 to .025 inch in diameter, Smith can add ribs and contours, lift edges, and fill corners. Toolmakers and molders are learning that microwelders like Smith now have the ability and technology to rescue molds and molding jobs.

Says Glenn Croner, owner of Loveland Tool and Die in Loveland, CO, "A welder can really make you or break you." Croner makes molds primarily for the computer industry; they range from a few pounds to 2000 lb. He relies heavily on Smith for making engineering changes, adding wall stock, and fixing parting line damage.

He says in the past many of the changes and fixes he needs would have necessitated a new or rebuilt mold and a lot of money. Now, he estimates, for less than 10 percent of the cost of a new mold, he uses microwelding. And the results are often the same as if he had rebuilt the mold. "Sometimes the weld is a permanent fix," Croner says. "Sometimes it gets us by to get the part out for the customer."Floyd Binder is a senior tooling engineer at Teledyne Water Pik in Fort Collins, CO. He says Teledyne Water Pik's molds have multiple cavities and are relatively small and complicated - susceptible to minor damage. As recently as a few years ago welds on molds were forbidden at Teledyne. "Our old policy was to not allow any welds on any of our molds. Period," he says. "But our man-hour expenses forced us to go to welders."

He adds that the quality of work being done by microwelders has allowed Teledyne to move away from its old practice of storing spare components and completely rebuilding a mold to fix damage or implement an engineering change. "Our participation with welders has grown tremendously over the last five years," he says. "It's saved us thousands of dollars in that we've not had to go back and rebuild a mold."

Greg Curtis agrees. He's the tooling supervisor at Plastic Technology, an injection molder based in Niwot, CO that molds computer parts as small as 1g and as large as 1 lb. He uses microwelding services to repair damage from stray arcs, to make engineering changes, and for minor mold touch-up. Curtis says he'd like to claim no need for welding, but like many in the industry, he's come to rely heavily on it. "I would like to eliminate welders completely, to say that I have a mold that is correct and doesn't need changes," Curtis says. "But in the real world, welders are very important to the trade."

Microwelding 101: What to Look For

What's changed so dramatically in the welding industry that makes microwelding so advantageous for toolmakers? Like most everything else in the industry over the last five to 10 years, the answer is simple: microprocessor control. Smith says a decade ago microwelding devices relied heavily on relays and analog switches to control electrical current. As a result, welding devices behaved unpredictably, alternately providing too little, then too much arc. This made microwelding an imperfect science, mostly insufficient to handle the level of detail required of many of today's mold repairs and changes. "The welders now have integrated microprocessor controls that make start-up easier and smoother," says Smith.

In spite of greater control, microwelding does not produce highly polished straight lines and corners. It's simply a means by which to precisely and carefully add steel to mold components. "Traditional welding is typically a means of joining," Smith says, "whereas this process is building up." So, the initial result may not be pretty, but it provides a toolmaker material that can be ground and polished to specification. "A weld is a weld is a weld, no matter how small," he says. "You're still going to have to machine or polish it."

In the end, the weld becomes an integral part of the tool, one you may never notice again. "It's getting harder and harder to distinguish welded areas from nonwelded areas," says Smith.

The results you get from welding will vary depending upon the process used. The three plagues of microwelding are temperature differentials, contaminants, and sinks. Smith combats temperature by pre- and postheating the tools on which he works. This brings the tool temperature closer to the temperatures introduced by the arc, preventing cracking and warping that can doom a small tool. Contaminants are avoided with simple cleaning before welding begins. Sinks, a result of poor temperature control, are prevented by way of pre- and postheating and good technique.

Even if a microwelder has avoided problems introduced by temperature, contaminants, and sinks, nonmatching steel can doom the tool. Smith says steel matching is vital, as different steels heat and cool at different rates.

What to Expect

If you're thinking of using microwelding to repair molds, Smith says you should prepare for a paradigm shift. "The attitude has been that if there is an error in the tool, then you scrap it and start over," he says. "Everyone has a set paradigm about welding. Microwelding forces people to shift paradigms. In the minds of most, welding does as much damage as it does repair."

Croner, Binder, and Curtis all agree that finding a good microwelder is both difficult and important. It's great to find one in your backyard, but most toolmakers are forced to send their microwelding repairs out of state. Smith estimates that there may be 10 to 20 independent microwelders in the United States, but that number might be going up. This month at its annual conference, the American Welding Society (AWS) is offering a tool and die microwelding seminar. For more information call AWS at (800) 443-9353, or see its website at www.amweld.org.

Prices for microwelding services vary, but in general they run a little higher than those for traditional welding, according to Croner, Binder, and Curtis. Some charge by the job, some charge by the hour. But, says Smith, "It's often cheaper than the alternative."

When you do find a microwelder, or if you've already got one, remember that like any profession, this one is not perfect. There may be changes or fixes that microwelding, or the microwelder, just cannot do. Make sure your welder knows his limits, lest you end up with a tool in worse shape than when you started. For larger welds, says Smith, remember that welding rods for microwelding are .005 to .025 inch in diameter (compare with .035 to .0625 inch for traditional welding), not large enough to practically weld an area larger than a nickel.

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