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Robotic EDM and Hard Milling Promote Press Uptime

By: Brad Kuvin

Thursday, March 01, 2012
 

Die complexity and size, and the quest for prolonged life of die components, are some of the issues keeping the toolroom at Wiegel Tool Works, Wood Dale, IL, on its toes these days. All the while, the company’s pressroom continues to require its dies to run at faster speeds and provide a higher degree of accuracy. With the acquisition in 2006 of a new 450-ton variable-stroke press—with a 120-in.-long bed—the firm now finds itself quoting numerous projects requiring more complex and larger dies.

Wiegel operates this EDM production cell that comprises two Mitsubishi EDM machines (an FA10P and FA20P) and a System 3R WorkMaster robot. The added flexibility from the automation allows the firm to perform on-demand machining of replacement tools to minimize downtime of its own stamping presses and those of its customers.
Wiegel specializes in stamping preplated copper-alloy electrical-circuit components such as fuse relays, with volumes as high as 4 to 5 million per year. The dies it designs and builds—for itself and for its key customers—now typically comprise as many as 20 progressive stations and are tasked with meeting part dimensional tolerances as tight as ±0.005 in.

Wiegel is fully committed to designing, building and maintaining all of its tooling inhouse, and invests as needed in new technology to ensure it meets the needs of its customers—internal and external. Among the equipment in its tooling department are vertical and horizontal machining centers. But what earns the most applause is a climate-controlled wire-EDM department boasting eight machines, including two working in a robot-tended workcell. EDM tolerances on die inserts are measured down to ±0.0001 in.

Recent Expansion

Wiegel works out of a 68,000-sq.-ft. facility, including a recently built 20,000-sq.-ft. addition. It also, in September 2011, acquired a nearby 25,000 sq.-ft. building to house shipping and receiving, as well as warehousing of finished goods and raw materials. The acquisition allowed the company to increase manufacturing capacity in its main building, evidenced with the addition, in December 2011, of a new state-of-the-art high-speed stamping line. The new line features a 180-ton variable-stroke Minster press and a high-end leveler-straightener. The straightener powers 13 rolls and backup rollers, designed to relieve stresses from higher-strength steels. More capacity means more dies. And, when making large capital investments such as a new press line, ensuring optimum press uptime is critical.

“We’re focused on developing tooling that will run faster and longer without maintenance, to optimize the uptime of our presses,” says Jerry Hampton, Wiegel Tool Works’ sales and marketing manager. “This directive drives our tooling department to develop new ideas and new technologies. If you outsource your tooling, you don’t get that dedication to continuous improvement and creativity. We find this a key to staying globally competitive, particularly challenging in our core electronics market.”

As an example, toolroom manager Rich Wiess describes a die that the Wiegel toolroom built in 2008 for another stamper/customer. The 90-in.-long die comprises 18 stations and runs plated copper-alloy components for electrical circuit boards that go into automotive transmissions. When the customer began to struggle with quality and on-time delivery, Wiegel took the die back, added some proprietary technology and saw immediate returns —uptime was increased by 35 to 40 percent, due to improvements such as changing the tool coating and engineering new features to better contain slugs.

“Each month, we look at all of our active jobs and identify five sets of tools to focus on,” says Wiess. “We investigate all sorts of options to retrofit new features to the tools, to increase their efficiency.”

“This is a key benefit to maintaining an inhouse state-of-the-art toolroom,” adds Aaron Wiegel, company vice president. “We can conduct research and development projects and realize huge gains in productivity. If a press goes down for die maintenance, we need our toolroom to get us back up and running in 24 hr. or less. In addition, some of the design enhancements we have made to our dies are truly unique —I’ve never seen some of these enhancements outside of our shop. So, we can keep that intellectual property inhouse, incorporate it into new tools—for us and for our key customers—and also retrofit the technology into existing tools. Turnaround and technology are the keys.”

Hard Milling, Automated EDM

Wiess and his crew boast that “there’s nothing we can’t make here,” noting most importantly its investments made a few years ago in hard milling. Before hard milling, the toolroom would machine die steels soft and send components out for heattreat.

“Again, our biggest cost here is downtime in the pressroom,” Wiegel reiterates, noting that the toolroom doesn’t generate much profit, if any. But, its level of performance sure can make a difference in pressroom productivity and profitability. Inserts that might have once taken two or three days to pre-machine, heattreat and wire-EDM now are hard-milled, tapped and wire-cut in an hour or two.

The Wiegel toolroom performs hard milling primarily for new dies—punch plates and strippers, for example. Describing the benefits of hard milling, Wiess points to the process of counterboring for pilot holes as an example.


 
The Wiegel toolroom performs hard milling primarily for new dies—punch plates and strippers, for example. Inserts that might have once taken two or three days to premachine, heattreat and wire-EDM now are hard-milled, tapped and wire-cut in an hour or two.

“Before, the dimensions of the counterbores in a block would vary depending on how much the block bowed during heattreating,” says Wiess. “Then we’d put the pilots in and grind the heads, and have to mark the pilots so that they would go back in the same counterbore. Now, with hard milling, the counterbores are identical, which allows us to place inserts in any position in the tool. Also, if we make any die changes—adding stripper inserts, for example—we can hard-mill that out, add a few tapped holes, make the separate stripper insert and install it into the stripper.”

Adding a robot to its EDM department, to form a two-machine production cell, also fits the bill when it comes to on-demand replacement of tools for the Wiegel pressroom. “If we need to get an insert made ASAP for one of our presses that’s in production,” explains engineering manager Joe Manschula, “we can quickly fixture a block and immediately insert the job into the cell’s production schedule.”

The automated cell comprises two Mitsubishi EDM machines (an FA10P and FA20P) and a System 3R WorkMaster robot.

Waterjet Cutting and Other Lead-Time Reducers

What’s coming down the pike for the Wiegel toolroom? Most likely, the firm will add a waterjet-cutting machine in 2012, “to relieve capacity issues from our wire-EDM department,” says Aaron Wiegel. “We need to increase capacity, and it makes more sense to add a waterjet-cutting machine than a new EDM. We’ll use waterjet to rough-out tooling and carve large openings in the blocks, which ultimately will reduce cycle times even more than they already have shrunk.”

Lead-time reduction has many faces at Wiegel, beginning with an investment made in 2005 into new 3D solid-modeling die-design and simulation software—Siemens’ NX. It also has standardized on die-plate thicknesses and tool steels.

“When die-design drawings are approved,” says Manschula, “rather than ordering blocks of steel from our suppliers, we can keep on hand large steel plates, cut them to the size specified and store remnants for future use. The plate then would be squared up and ready for tapping, minor machining, heattreat, and a final skim pass on a wire-EDM machine.”

Wiegel was, back in 2003, a beta site for NX and Siemens’ optional Progressive Die Wizard module. The module significantly reduces modeling time from hours to minutes, says Wiegel, and also displays strip-layout simulations for immediate feedback when making design and process changes. Design time, he says, was reduced by about one-third when the software became fully functional, and his pending investment in waterjet cutting is expected to reduce lead times by another 15 to 20 percent.

“Waterjet cutting will increase the speed at which we execute roughing cuts,” says Wiegel, “by a factor of 10 to 15 when compared to EDM.”

“The way we do it now,” adds Wiess, “adds three to five days to our lead times by the time we order material after having received a final die design. Then we have to pay for squaring of the blocks. Waterjet will eliminate that process, and our heattreating costs will drop, since we pay by the pound.”

Not only will faster turnaround of new dies help its own pressroom, but Aaron Wiegel finds that customers are getting used to paying a premium for speed. He counts about 20 key stamping customers that source his company for tooling.

“We see OEMs dragging their feet when launching new programs, for a number of reasons,” he says, noting that while a project’s launch date may get delayed, the date of first-part off rarely if ever moves accordingly. “When this happens—and it happens quite a lot—the quoted lead times of our customers can shrink by as much as 60 percent, and they often must pay expediting fees to meet the original target date. If we can continue to reduce our lead times to help our customers meet their goals, that makes us that more attractive.” MF

 

See also: Mitsubishi EDM/Laser, Siemens Industry, Inc.

Related Enterprise Zones: Tool & Die

 


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