July 2008 Edition

CUTTING TOOLS

It Pays to Find an Expert

When new machining technology provided tooling challenges, a clutch-brake manufacturer sought expert advice for its tooling needs

When customer requirements mean a change in technology, it often means a new machine. But, with that comes new problems. Sometimes expert advice is needed to use the upgrade to its fullest capacity.

Force Control, Fairfield, OH, produces industrial clutches and brakes. As the developer of the Posidyne clutch-brake system, the company makes oil shear, heavy-power transmission clutches and brakes used in a variety of industries. As customer requirements change, so do Force Control’s.

"During the past six or seven years, the economy has had a dramatic effect on our customers’ operations," Steve Spurlock, a company machining specialist, said. "They used to buy spare products to keep in inventory. Now our customers order a product when they need it, and expect faster turnaround. They also exert pricing pressure on us. It’s a huge challenge."

To meet the changing needs of its customers, the firm created a process team. The team employees were responsible for researching and implementing Lean initiatives. After evaluating various technologies, the team found operations improvements by adopting a multi-task machining center. Upon the team’s recommendations, management purchased an e-800 V/5-II from Mazak Corp. When the machine arrived, the process team faced implementation.

"Multi-task technology is different than anything we had before, so almost everything was a challenge," Bill Ashley, the process team leader, said. "Fixturing, tooling, and programming were all issues with which we had to deal.

"Tooling was the biggest challenge. We’d been in the habit of porting over existing tools when we bought a new machine. The Mazak’s technology was so different we couldn’t do that this time."

Rude Awakening

After evaluating the machine and the cast iron parts it would produce, the company’s tooling supplier recommended a list of tools. The process team tested them and found that several did not perform at the levels required. To get the results needed, the team conducted additional research, compiled its own list of tools, and submitted the order to its tooling supplier. They received a rude awakening when the tooling package arrived.

"We found that quite a few of the the tools were items we didn’t order," Ashley said. "Our tooling rep was more a salesman than an expert. When we continued having tooling issues, we looked at other options."

At the suggestion of its Mazak representative, the process team met with Sandvik Coromant, Fairlawn, NJ, to discuss tooling for the machine. Boring bars were the initial focus of discussion. The company used Cat 40 mill holders with 1.75" boring bars, but the results were poor, with chatter throughout the machining process. The chatter had a negative impact on surface finish, a vital necessity in the quality of the company’s oil shear clutches and brakes.

After reviewing the application requirement, the local Sandvik representative recommended Big Plus Capto holders with Capto boring bars. Tests showed an immediate improvement. The Capto combination maintained the required tolerances of 0.001", with the required surface finish of 32 µm. Tool life increased as well. The company asked Sandvik to examine the rest of the tooling being used on the multi-task machine.

Boring Chatter

Similar to the boring application, the company experienced chatter problems and limited tool life in grooving and back-facing applications. The Capto combination eliminated those problems, too. Milling operations were underperforming, too. For face milling, cutting speeds and feed rates maxed out at 475 sfm for rough cuts and 22 ipm for finish cuts. There were significant problems with tool life, and the company had to perform multiple roughing passes.

"To get the existing tooling to work, they were pulling it back and taking light cut depths and multiple passes, productivity really suffered," Dale Reliford, the Sandvik Coromant representative, said. "If they used the right CoroMill products, we’d be able to increase productivity."

The team chose the CoroMill 390 and CoroMill 365. The company achieves a cutting speed of 1,000 sfm with the CoroMill 390, with a feed rate of 17 ipm and depth of cut of 0.020" for the finish cut. For roughing, the CoroMill 365 increased cutting to 700 sfm, with a feed rate of 48 ipm. The depth of cut was raised to 0.160" per pass. Together, the tools reduced milling time by 30 percent and resulted in a 100 percent increase in tool life.

"For every tool we were using, there was a better solution available," Spurlock said. "We might have discovered some of these on our own, but the advantage lay with having someone with the right tooling expertise come into our shop and show us how the latest tooling innovations apply to what we’re doing."

With the proper tooling, the company began reaping the benefits of its new machine. The cast iron components produced on the Mazak once required a total of 7.75 hours of machining. Now it’s three hours.

Time spent on setups dropped as well. Under the old processes, a component would move through six different machines before completion. Total time for all setups was at 15.5 hours. With the Mazak’s multi-task capabilities, parts now require two four-hour setups.

While reductions in machining and setup times helped achieve greater efficiency, the largest benefit is shorter lead times, according to Ashley. Rather than moving from machine-to-machine and taking up to several weeks to be completed, parts are now finished at a single station. A significant amount of workflow has been eliminated from its schedules.

"The technology of the e-800 V/5-II is everything we expected in terms of benefiting our operations," Ashley said. "Looking back, the only thing we should’ve done differently was working with a knowledgeable tooling supplier as soon as we began the purchase process." Sandvik Coromant

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