Advances in quick die change
May 30, 2002
This article outlines how operational changes, planning, and combinations and adaptations of existing technologies are upgrading quick die change. Die standardization and new technologies, such as mechanical die lifters, box-style lifters rolling bolsters and programmable logic controllers, is making quick die change more efficient and cost effective.
|Photo courtesy of Atlas Technologies.|
What's new in quick die change is more subtle than breathtaking. Because the basic design of a typical press line leaves a limited number of options for technological improvements, "new" is best applied to things like operational changes, planning, and combinations and adaptations of existing technologies.
Also new are manufacturers' attitude and willingness to create and implement a plan designed to make their businesses more profitable.
"What's new in quick die change systems has a lot to do with who's buying quick die change systems and why," said John Campbell, sales manager for Wayne Trail Technologies Inc., Fort Loramie, Ohio, a manufacturer of press automation (www.waynetrail.com). "We've seen a transition from just the larger automotive companies buying die change systems to smaller companies looking for process improvement. Much of it has to do with adjusting to just-in-time requirements."
When U.S. sales of Japanese automobiles skyrocketed during the 1980s, Americans became sold on more than just less expensive cars. They bought a new manufacturing philosophy known as JIT manufacturing, which meant doing away with large inventories and producing parts in smaller batches. This leads to more frequent die changeovers.
Adoption of JIT during the 1990s pushed the development of quick die change technologies such as rolling bolsters and die carts. Standardization became another quick die change tool with standardized bolster plates and clamping systems. Despite these improvements, change has been slow in coming.
"The technology we have is not being used fully by the industry," said Jan Termuehlen, president of Optima USA, Elm Grove, Wis., a manufacturer of die clamps (www.optimausa.com). He cites cost, lack of time, and limited resources for planning as the biggest factors influencing manufacturers' underuse of new technologies.
As the industry evolves and ushers in new technologies, quick die change experts agree that the need for planning is more important to manufacturers. In today's changing marketplace, manufacturers need to be flexible, and quick die change can increase flexibility, said Barry Bomier, manufacturing consultant with William-Lynn-James Inc., an economic development and public policy consulting firm, Carmel, Ind. (www.w-l-j.com).>
Quick die change increases flexibility more than any other technique, according to Bomier. When planning for JIT production, he recommends stabilizing the production system, creating a uniform work load to produce the same product mix each day, shortening or eliminating setup times, and reducing lot sizes and lead-times.
"A huge component of quick die change is internal planning in the facility," Termuehlen said. "This doesn't include any hardware. It is determined by how effectively an operator plans and manages the schedule for that day. This means not only running the press but everything downstream, such as where the die is stored, if it's ready to go, and if it has been cleared and inspected."
"Tooling is just one aspect," Campbell said. "If other things are not compatible for a synchronized change, stampers are defeating the purpose of spending money on quick die change. If it takes 10 minutes to change over the die, and a half-hour to an hour to change the feed or transfer, the capital expenditure is not fully optimized."
Once a plan is developed, it must be implemented, which usually is not a one-step process.
"Keep on enhancing and enhancing the process until optimum die change time is reached," said Olav Vangstad, president of American Aerostar Corp., Valencia, Calif., a manufacturer of equipment for quick die change systems (www.astar.com). "I say optimum because it indicates that stampers should maximize press uptime consistent with retaining equipment flexibility and meeting return on investment criteria."
Although a not-so-new idea in practice, die standardization is a way to improve die changes. In some instances, standardization can be the easiest, quickest, least expensive, and best method for setup improvement, said Dennis Cattell, regional sales manager of The Minster Machine Company, Minster, Ohio. Minster Machine is a manufacturer of mechanical power presses and related auxiliary equipment (www.minster.com).
According to Cattell, it is the first area to consider when planning a quick die change system, particularly for progressive die applications, because it eliminates the need to customize each individual die setup. He also notes that standardization is a prerequisite for implementing many other improvements, such as automated rolling bolster technology, automated die carts, and automated storage and retrieval systems.
Standardizing characteristics such as shut height, clamping height, clamping location, pass height, and die location on progressive dies is the first step to implementing quick die change—which can be accomplished in a company's own machine shop or custom-retrofitted, said Cattell.
Standardization features of a transfer press to facilitate quick die change include parking the finger bars right on the die itself and automatic uncoupling and removal of tooling, according to Campbell.
"In the past transfer presses often had dedicated automation for each press," he said. "Now one machine can use multiple dies or tools in the same press with the same automation."
Another version of the mechanical die lifter can be used rollers down and rolls with the die when moved. Dies with parallels but no bottom plate now can be rolled across the top of a bolster supported by two rollers-down die lifters. A pair of die lifters is usually inserted in 11¼2-in.-deep slots milled into the bottom of two parallels. Dies are rolled on and off a flat surface, such as a table or cart, which is positioned at the press during die exchange.
According to Vangstad, other advances include a box-style die lifter and roller. Similar to a car scissor jack on wheels, it helps move dies with parallels. In this case, a pair of die lifters are placed between and against two parallels before the die is elevated.
The box-style die lifter can be adjusted for parallel height. A wrench is needed to elevate the die to 0.06 in. before the die is moved. When the die is in place, the lifters are relaxed and removed.
Dies with parallels often are placed directly on forklift trucks with bolsters. However, when forklift access is restricted, rollers reduce rolling friction to approximately 1 to 2 percent of die weight, allowing for die push-in and push-out.
Rolling bolster technology through retrofit adaptation also is evolving.
"Manufacturers used to buy a quick die change system and a brand-new bolster, but now operators can specify the speeds, feeds, and the clamping system required," said Robert Kotynski, president of United Machine, Valparaiso, Ind., a manufacturer of metal forming equipment (www.unitedmachinecorp.com).
Designs feature a bolt-on track placed in the press that does not require machining the press bed or breaking up the floor.
Although the basic hardware technology for quick die change is the same, the application of computer controls is advancing.
"Many things can be done with programmable logic controllers, such as creating a rolling bolster with a brain," said Kotynski. Used with a programmable logic controller, a rolling bolster can be tied into a quick die change system, which automates the operation from unclamping to rollout.
"That kind of technology didn't exist before programmable logic controllers," he said. "And it didn't exist at the cost you can now retrofit these. Manufacturers don't have to spend the capital they used to."
Although not in widespread use, programmable logic controllers can create a hands-free production environment, according to Kotynski.
"Programmable logic controllers assist in positioning the ram and unclamping the die to ensure that the press is blocked out, all the way to the final rolling of the bolster in and out of the press," Kotynski said. "If you have numerous production variables, programmable logic controllers will reduce human error because changeover is automatic."
Detailed planning for any system improvements involving quick die change is vital, especially improvements involving increases in technology, Kotynski said. "Successful automation and computerization in a stamping house require planning, project management, and organization."
Implementing quick die change is much more than installing new technology; it is a process that requires input and cooperation from all levels of a company to make the technology efficient and cost-effective.
When it comes to what's new in quick die change, it's the attitude, not the magnitude, that can increase productivity and the bottom line in this new era of manufacturing.
Patrice A. Kelly is a free-lance writer based in Cleveland, Ohio, and can be reached at firstname.lastname@example.org.
STAMPING Journal acknowledges the following sources used in preparing this article:
American Aerostar Corp., 25014 Avenue Kearny, Valencia, CA 91355, phone 800-780-9850, fax 661-257-6609, Web site www.astar.com.
Atlas Technologies, 201 S. Alloy Drive, Fenton, MI 48430, phone 810-629-6663, fax 810-629-8145, Web site www.atlastechnologies.com.
The Minster Machine Co., 240 W. Fifth St., P.O. Box 120, Minster, OH 45865, phone 419-628-2331, fax 419-628-3517, Web site www.optimausa.com.
United Machine Corp., 753 Axe Ave., Valparaiso, IN 46383, phone 219-548-8050, fax 219-548-2053, Web site www.unitedmachinecorp.com.
Wayne Trail Technologies, 203 E. Park St., Fort Loramie, OH 45845-0257, phone 937-295-2120, fax 937-295-2642, Web site www.waynetrail.com.
William-Lynn-James Inc., 11711 N. Meridian St., Carmel, IN 46032, phone 317-972-4242, fax 317-736-4323, Web site www.w-l-j.com.