EDM for the long run: to manufacture large quantities of similar parts, a Georgia machine shop has found that wire EDM is the ideal process

Modern Machine Shop, Feb, 2002 by Bill Dundas

Because it plays a supporting role in many shops, wire EDM isn't widely associated with high-volume production. But metalworking professionals who choose wire EDM as their mainline process continue to develop strategies that boost its efficiency. Thus, many of those at the forefront of wire EDM applications view this technology as undervalued by shops that use it only for secondary operations.

Robert W. Jenkins, president of Bellwether Inc. (McDonough, Georgia) is a firm believer in the untapped potential of wire EDM. His company's success in providing high-quality, precision parts for various industries confirms the proposition that, in some cases, wire-cutting represents the most effective machining process.

As a former employee of Amoco Chemical Company's Fabrics Division, Mr. Jenkins was closely associated with Georgia's carpet-backing industry during the early 1970s. Polypropylene is a byproduct of gasoline refining, and Amoco was developing a market to use this plastic in woven form to replace the traditional jute backing of carpets. In the course of his work, Mr. Jenkins became familiar with the dominant type of weaving machine used by various fabric manufacturers. Focusing on small, consumable parts used by this machine, Mr. Jenkins identified an important market for replacements. This opportunity convinced him to establish his machine shop in 1975.

Today, Bellwether Inc. is a 30-employee shop located in the northern Georgia countryside, a short distance south of Atlanta's urban sprawl. Although it resembles a typical job shop in many ways, wire EDM represents the heart of Bellwether's operations. On the shop floor, Mr. Jenkins combines the latest EDM technology with conventional metalworking methods to effectively address the specialized needs of his customers.

Adapting To New Conditions

The business downturn that currently affects manufacturing arrived somewhat earlier for the Southeastern textile industry. After experiencing strong growth between 1988 and 1992, Bellwether's textile-related business remained steady until 1998. From 1998 to 2000, however, strong foreign competition created substantial weakness in the domestic industry, and Bellwether experienced a sharp, 30-percent reduction in its work for textile companies.

According to Mr. Jenkins, this resulted from saturation of the American textile market with low-cost imports.

As a consequence, Mr. Jenkins began to explore opportunities to replace some of the business that his firm had lost. "We've found that, if you're going to survive today, you need to be very broad-based," he says. To this end, the company recently established a close relationship with a major domestic manufacturer of power tools. Bellwether designs and fabricates ergonomically friendly tool fixtures that are sold as accessories to manufacturers whose employees use power tools to perform repetitive assembly tasks. This is a promising area for future growth, as manufacturing firms endeavor to meet government regulations in the workplace. "We have found ways to reduce exposure to cumulative trauma injuries," says Mr. Jenkins. "We believe this is very important work because it directly and positively affects employees' daily productivity."

Another important source of new business for Bellwether is the design and fabrication of new types of automatic assembly machines for the recreational products industry. For example, the shop is currently building a machine that automates installation of the rubber molding around the perimeter of a tractor windshield. A second project involves redesigning a metal forming machine that creates small wheel hubs.

By diversifying his shop's work, Mr. Jenkins doubled the level of Bellwether's non-textile business in only one year. The shop's current business consists of approximately 60 percent textile-related work, with the remaining 40 percent comprising parts, fixtures, dies and tooling manufactured for the mining, aerospace, medical and recreational industries. Approximately 75 percent of Bellwether's work is performed for domestic customers. Exceeding the norm for metalworking shops today, Mr. Jenkins reports that his sales improved 18 percent during the past year, and he anticipates at least 10 percent growth in the current fiscal year.

Complex Simplicity

Originally focused on in Bellwether's business--and still important in its success--are parts known as "feeder grippers" and "shuttle grippers." These are small parts that grip and carry weft yarns as they are drawn through the weaving machine and inserted into the fabric as it's being woven. Because this machine's operation is entirely dependent on proper functioning of these parts, they must be designed and machined to exacting specifications.

Although the parts appear quite simple in design, they must be capable of withstanding the rigors of continuous production. Because of varying fabric requirements for different fabric grades and manufacturers, Bellwether has made 95 versions of this part. The grippers also incorporate several different jaw designs for handling various fabrics, and the jaw tension must be carefully matched to the specific fabric application. Mr. Jenkins' strong commitment to quality enables his shop to produce parts that are superior to those furnished by the weaving machine's original manufacturer. This represents an important factor in Bellwether's ability to sustain its textile-related business.