VMCs cut high-volume, boost shop production

Manufacturing Engineering, Jul 2000

To remain competitive in the parts manufacturing market, Jim Paas, vice president of Mistequay Group Ltd. (Saginaw, MI), knows that investment in new machining centers with the latest technology is essential-even if it means replacing machines only a few years old.

Since 1991, Mistequay has provided diverse machining capabilities for automotive, aircraft, and off highway vehicle industries, as well as customers in the hydraulic and foundry industries. Mistequay offers a range of machining services from prototypes and experimental parts, to small, medium and large-lot production. This variety calls for working with many materials to produce highly complex parts machined from solids or from castings.

To win a contract to produce a cast-iron part, the company based its production contract quotation on replacing older VTC vertical machining centers from Mazak Corp. (Florence, KID with state-of the-art Mazak VTC-200B VMCs.

"The throughput of the Mazak VTC200Bs allowed us to over a more competitive price to our customers," Paas says. "We priced the job to reflect the increased performance, and offered our customer a big reduction from what he'd been paying. Since we've been in production, the VTC-200Bs have met all of our expectations." Actual cycle-time reductions averaged about 50`x.

Mistequay runs 40006000 units per week of the cast iron part on four Mazak VTC-200Bs organized in one workcell. A special dedicated rotary fixture positions and locks two parts at a time in place for machining multiple sides using various types of cuts, including drilling, milling, and tapping. Paas notes the job really could have lent itself to a transfer line, and in fact, another supplier was using a transfer line to produce a similar part.

"To stay efficient on the VMCs, we are using a modified workcell approach," Paas says. "We fixture two parts on each table and program specific short toolpath movemenu, taking advantage of the machines' high rapid traverse rates and quick chip-to-chip times. With the cell concept, and having each machine do only a portion of the overall process, we gain savings over cutting a whole part in one machine. Using this approach, we're getting much higher production than we had a few years ago.

"After a brief startup period, we are meeting the aggressive times we projected to machine certain operations on these parts."

Paas says that with the versatility of the CNC equipment and their rapid speeds and feeds they are slowly replacing transfer lines. "When you have machines that can do what these Mazak VTC-200Bs can do, you're going to see more transfer lines replaced. When machining speeds are so great, you don't have to worry about part loading times. And with bigger machine tables, you can get more parts on them.

"Programming is real important to us. With the available workforce's lack of training today, it's hard to find good people. But with Mazak's CNC control, it's relatively easy to bring someone in who has never seen one before and start them out on repetitive jobs. And even though Mazak's CNC controls are easier for the lesser-skilled operator, they still have the complex capability to do tough-to-- machine parts."

For the future, Paas says Mistequay will go into different locations and specialize in certain areas, but the company likely will stick with its standard business. "We think our market mainstay is the same 25 to 250-piece part runs that require multiple setups and long-term contracts," Paas says.

Mistequay also is looking to develop itself into a digital factory, with all of its plants linked through the Internet using Mazak's Mazatrol Fusion 640 PC CNC control, which allows machines to be monitored from any interconnected PC. With this concept, company management will be able to better monitor total workflow, from the ordering of raw goods and machine maintenance and service, to the delivery of finished parts. Circle 304.