It's no easy feat for a manufacturing operation to change its production strategy. And when a high-volume production process is involved, the prospect of change is even more daunting.

Such was the challenge taken on by TRW Automotive of St. Catharines, Ontario, Canada. The company—the eighth largest automotive supplier in the world with more than 25,000 employees in North America—sought alternative ways to machine forging dies in its steering and suspension systems division. The reason was internal. Its mature, relatively inflexible production process could no longer keep up with its increasingly demanding forging operations. The solution: high speed machining.

The company's St. Catharines plant—which employs about 800 people—formerly relied on a process that involved creating masters of all forged parts, copying electrodes from these masters, and machining die cavities using EDM (electrical discharge machining). The method not only required many operators but also the use of 12 ram EDMs, five duplicators and an abrader. TRW needed a more efficient process, and this prompted the company to set up a demonstration in which its forging dies were milled on high speed machines. "The demonstration proved beyond a doubt that this would give us the ability to cut hardened materials at significantly increased feed rates," says CNC programmer Robert Chausse. Next came the hard part.

The Pains

Making the transition to high speed machining—a $4 million investment—presented many difficulties for the company, which makes a broad variety of original equipment and aftermarket products including braking systems, chassis parts, steering systems, engine components and engineered fasteners. At the time that TRW Automotive switched to high speed machining, the technology was still in its infancy, with a limited selection of appropriate machine tools and an inadequate support network. As a result, the company's managers had to be proactive in realizing the capabilities of this technology.

First, the company's veteran machinists had to adjust to the drastically different concept of high speed machining, a process that challenged their basic assumptions and long experience with conventional cutting tools. High speed machining involves taking lighter cuts with smaller tools to produce smoother part surfaces. And once the first of four high speed HMCs was installed, the company soon faced some difficulties. TRW machinists went through a period of trial and error, experimenting with different machining parameters in an attempt to figure out the most ideal conditions for its production process. "We destroyed some spindles in the beginning because we believed that the machines could be run more aggressively than what actually proved to be the case," says Chausse.

Another obstacle was the limited selection of cutting tools for high speed machines. "There were only a handful of suppliers for these tools, and the tools were very expensive," says toolroom coordinator Norm MacLeod. "Because we didn't have our machining process perfected for several months, we initially purchased a number of tools that we later discovered could not be used." Eventually, the company's toolroom managers found out that the range of tool sizes they needed was not as wide as anticipated—1/4-inch and 1/2 inch-diameter tools would be used extensively.

To manage the transition process, the company enlisted the help of management, information services, engineering and its seasoned team of toolmakers. A cross-functional team was formed, and the company was able to ramp up the process to full production—which took roughly a year from the time the first high speed machine was up and running—while satisfying ongoing production demands. It accomplished this by first introducing the process in the production of dies for a single part and then slowly applying it to the complete line of tooling.

The Gains

This huge undertaking has certainly paid off for the company, which has seen dramatic increases in productivity since its switch to high speed machining. The new process has halved the toolroom's overall process time for die production. Moreover, it has trimmed the number of steps needed to manufacture tooling from nine to only six and significantly boosted labor efficiency. "Compared to our old method, we're able to produce more dies today with considerably fewer people," says MacLeod.

Because of its reduced cycle times for finished and remanufactured dies, the toolroom can now respond much more quickly to changes in production demands. And with shorter lead times for tooling production, it has been able to better support the forging department, embracing a JIT production strategy and achieving a level of flexibility that would not have been possible with its former EDM process. Moreover, the toolroom is now more responsive to changes in part designs, helping the company improve both production planning and customer service.

For metalworking companies of all sizes, TRW Automotive's example illustrates the importance of rethinking longstanding production strategies and facing the difficulties of transition head on. The company's managers were undeterred by the relative newness of high speed machining, embracing the technology even though it was risky and unproven at the time. (High speed machining has certainly come a long way since then.) And they were rewarded with tremendous efficiency gains.

Source:
Forging a New Strategy
Bill Dundas
MMS Online, Aug. 2003
www.mmsonline.com/articles/080304.html