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Wired for Success

May 13, 2009
Medical shop cures its production ailments with a Wire-EDM transplant.
Only two operators set up and run all the wire EDMs at Greer Manufacturing, including the medical shop’s line of nine Fanuc wire EDMs.

Manufacturing medical devices is a painstaking business. Shops that do so must produce parts with a high degree of accuracy, reliability and durability – all while facing competitive pressures to reduce costs and time to market, and having to deal with extensive FDA and other regulations.

Greer Manufacturing Inc. is one shop that meets these challenges on a daily basis. The family-owned and operated shop in Prospect, Conn., has been serving the medical industry, among others, since 1989, and 95 percent of its business involves machining state-of-the-art, close-toleranced and high-precision medical instruments.

Parts typically measure between 0.500 in. and 1-in. wide, and are made from metals such as titanium and stainless steel. Most of Greer Manufacturing’s customers demand ISO9000 compliance, with part feature tolerances around +/- 0.0003 in.

In addition to meeting job requirements, the shop must constantly look for ways to improve its manufacturing methods or run the risk of losing work. With that said, Greer Manufacturing decided to incorporate wire EDM because of that technology’s capability to accurately create complex or simple part shapes and geometries.

Previously, the shop was using manufacturing methods that involved a number of vertical machining centers that required extensive tooling and labor. Part manufacturing was a multi-process operation and a complicated task to manage. And to keep the machines running around the clock took six operators.

Unfortunately, after purchasing its first few wire EDMs, Greer Manufacturing experienced some downsides to the technology and became disappointed with their machines’ performances, as well as the associated costs and maintenance.

“After our initial EDM experience, we found a number of issues we needed to pay close attention to. With some types of wire EDMs, there are problems with their automatic wire threaders. Besides that, we had to use a more expensive zinc-coated wire to achieve the speed and accuracy we needed. Plus, the wire would flake off in the manufacturing process, forcing us to frequently replace wire, filters, diamond guides and other expensive consumables,” related David Greer, vice president of Greer Manufacturing.

Despite these setbacks, the shop wasn’t quite ready to completely pull the plug on wire EDM. It actively sought out a second opinion from a supplier of precision machine tools, Methods Machine Tools, which led to Greer Manufacturing purchasing its first Fanuc wire EDM.

The Fanuc machine didn’t have the wire-threading problems, eliminated most deburring and buffing from Greer Manufacturing’s part production, and reduced multi-operational jobs to just two-operation jobs. For the shop, this contributed to a 10-percent reduction of an overall per part cost reduction, and that amount multiplied by the 5,000 to 10,000 parts the shop produces each month added up to significant cost savings. Greer Manufacturing had so much success with the first Fanuc EDM, that it purchased eight more.

The Fanuc wire EDMs are also easier to set up, require less servicing and are more accurate. So much so that they reduced Greer Manufacturing’s scrap rate to less than 1 percent. But most important, the machines provide the ability to run unattended lights-out, to boost the shop’s productivity by 60 percent.

Perhaps the greatest cost savings came from the Fanuc wire-EDM features that simplified many tasks for operators, which allowed Greer Manufacturing to reduce the number of operators needed to run the equipment. Two operators, as opposed to six for the previous machining scenario, now operate the shop’s EDMs.

In addition, the Fanuc wire EDMs include a standard feature called Cut Monitor that allows for remote machine operation and process monitoring to eliminate the need for a nightshift.

“We gained more hours of the day with the addition of the Fanuc machines,” Jim Greer, president of Greer Manufacturing, said. “We do more work with less people to significantly increase our productivity.”

Besides Cut Monitor, several other aspects of the Fanuc EDMs proved beneficial to Greer Manufacturing. Some of these include the machines’ automatic wire-feed/threader systems, power supply technology and power discharge monitoring systems, and nano interpolation capabilities.

The key to success for a Fanuc wire EDM’s automatic wire feed/threader is the fact that the system anneals the wire prior to the threading operation, and puts a point on the end of the wire. This allows the machine to thread fully submerged over its total Z-axis height in most applications, to virtually eliminate unwanted “misses” during the process.

To produce workpieces faster and more accurately, Fanuc wire EDMs use the latest in power supply technology. The supply couples the machine’s productivity and profitability with affordable operation costs and high speed.

A patented power-discharge monitoring system, called AI Pulse Control, sorts and counts each discharge pulse of the Fanuc wire EDM. This level of discharge monitoring makes it possible for the machine to automatically compensate and adjust for poor cutting conditions to maintain greater cutting speeds regardless of gap contamination.

AI Pulse Control also optimizes cutting speeds in interrupted, stepped or irregular-shaped parts where poor flushing conditions exist, making opengap cutting easier and more productive. With the AI Pulse Control, operators can run the machine at the highest possible speeds without wire breaks occurring when open gap conditions are unavoidable. This means there is less time spent building fixtures and more time actually cutting workpieces.

For improved NC command resolution, Fanuc wire EDMs incorporate the Nano Interpolation feature. When processing workpieces, the NC command resolution is 0.00000004 in. with Nano Interpolation. Extremely close positioning accuracy to the programmed cutting path is achieved for producing workpieces with extremely tight tolerances.

In addition to the features of the Fanuc wire EDM, its low maintenance costs have also helped improve productivity and reduce consumable costs for Greer Manufacturing.

“The cost of consumables, such as filters and replacement wire, has drastically been reduced. And the time that our other EDMs were down has dropped from each machine being down for a few hours weekly to a short time, perhaps only once a month for routine maintenance, with the Fanuc wire EDMs from Methods,” commented Stephen Greer, a vice president at Greer Manufacturing.

Information for this article supplied by Methods Machine Tools.

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