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Tool & Die

Shedding scrap

By Lynn Stanley

A simple device solves a stamping scrap problem for Rotor Clip

April 2012 - When Rob Grinthal encountered a scrap problem that caused random defects in a part stamped from high carbon steel, he discovered a solution in a product called Shed-It. Able to combat the challenges associated with slug and part retention, the ejector system effectively separated scrap from a punch during a progressive stamping job when conventional methods failed.

Grinthal, chief engineer for Rotor Clip, Somerset, N.J., saw a brochure about the device. “I read it and thought it could be a fit for our problem,” he says. “I called Dick Greenleaf at Crystal Engineering Co. Inc. and explained my application. He got excited and sent me samples to try out.”

Greenleaf, then president and owner of Crystal Engineering, a Newburyport, Mass., metal fabrication company, initially invented the Shed-It to solve scrap problems with his own high-volume, high-speed stamping line. Crystal Engineering’s design, product development, metalforming and tool and die services support a variety of customers in markets including medical, aerospace, defense and automotive.

“I’m not an inventor, just a metal stamper that sometimes gets into hot water trying new approaches,” says Greenleaf.

Innovation
Greenleaf found conventional ejector punches ineffective at more than 400 strokes per minute. The stamper tried containing slugs within the matrix but found newer steel materials caused parts to burr. Part runs became shorter. Slug pulling and part pumping plagued production of the specialized parts, which had to meet stringent quality standards.

“We spent three years developing the Shed-It and two years using it and refining the design in production,” says Greenleaf, who holds the patent on the technology.

The Shed-It since has proved to be a reliable system for eliminating most ejector failures and die damage while drastically reducing downtime. Greenleaf’s daughter, Lisa Greenleaf, marketing director at Shed-It, calls the device the sticky note of metalforming. “It’s such a simple device yet solves a lot of problems in the tool and die world,” she says.

The invention, along with the company’s unique operations, also captured the interest of Michael Trotta, who purchased Crystal Engineering in December 2011 and retained Dick Greenleaf as a key consultant. Trotta, who comes from a family rooted in New England-based businesses, originally worked in financial planning and then as an importer for American companies making parts in China.

“After the economic downturn, I began to think about manufacturing at home,” he says. “Crystal Engineering is primarily a washer maker but has the potential to support the new face of manufacturing in the U.S. with its design capabilities. The company’s solid foundation is built on high-speed and short-run stamping and wire EDM and CNC,” says Trotta. He credits Greenleaf with its setup and creative atmosphere. “He has a lot of ideas he has yet to launch. We’ve retained the original workforce and are bringing in new hires like an engineer to help bring some of those ideas to fruition,” says Trotta.

Grinthal says Greenleaf’s innovative thinking helped his team tailor the Shed-It to its application. Rotor Clip manufactures a full line of inch, DIN, ANSI metric and JIS retaining rings to customer specifications worldwide. The fabricator’s product line also includes constant section rings and self-compensating hose clamps, which provide a cost-effective, reliable alternative to conventional devices used in low-pressure applications for the automotive and appliance markets.

Rotor Clip uses primarily progressive stamping operations to produce its parts.

One stamping operation, running at 100 strokes per minute, used high-carbon-steel wire to form a retaining ring anywhere from 40 mm to 100 mm in diameter. The wire was coiled into a circle or ring then placed in the press to be formed into the part’s contour, which included holes and two end cuts. Scrap from the stamping process was minimal.

“When you stamp parts from a metal strip, the percent of part to scrap is roughly 85 percent scrap and 15 percent part,” says Grinthal. “With wire material, the ratio is reversed. You get 85 percent part and 15 percent scrap. You can run the part fast, and scrap really isn’t a consideration, regardless of the part’s size. With this particular product, we had two pieces of scrap we could not contain. Orders could go from 100,000 to 5 million parts a year.”

Potential existed for scrap exiting the die to become embossed in the next part, creating a defect. The problem might occur only once in 10,000 parts but was nearly impossible for Rotor Clip personnel to detect. “It was very infrequent, but if a customer handles 100 percent of the parts and one in 10,000 is defective, he’s not going to be happy,” says Grinthal.

Tool redesign
For Grinthal, the quest to contain the scrap was critical. Using geometry, Grinthal and his team tried reducing surface tension with a cutting fluid as well as reducing the surface area to which the part stuck. “We demagnetized the operation and even contemplated blowing air across the tool,” says Grinthal. “The Shed-It turned out to be the cleanest solution. We had to redesign our tooling to accommodate the Shed-It, but it proved to be the easiest, most-effective route.”

During the modification process, Grinthal says Crystal Engineering’s support was a contributing factor. “Dick called numerous times to see how the Shed-It devices were working for us,” says Grinthal. “Because of our application, we needed to use the Shed-It differently than the way Dick was using it on his shop floor. Initially, the heads tended to pull off the urethane bodies, so Dick replaced the parts free of charge and improved the bond to eliminate the problem. Our unique method of using the Shed-It also tended to cut off the end tip. Dick made a suggestion to remove the sharp corner on the tool the Shed-It interfaced with. That cured the problem.”

Once modifications on the Shed-It were complete, Rotor Clip’s quality control department performed an audit and found the device had eliminated the operation’s scrap problem. According to Grinthal, the Shed-It physically ejects scrap from the punch so it can’t stay with or follow the punch back up. “Now that we know what the Shed-It can do for us, we’re looking at other types of production,” says Grinthal. “We’ve roughly converted 65 percent of our tooling to accommodate the Shed-It. We started with our top-10 worst cases. We’re still working to retrofit all our tools, but we’ve gotten rid of our hot spots.”

Fabricators still using conventional ejector systems have to contend with wear and tear on the pin, spring and set screw. “The spring can become ineffective over time,” says Greenleaf. “The Shed-It lasts as long as the punch. You can even repurpose the Shed-It into shorter punches. Any metal stamper running progressive or compound dies or knock-outs has problems with slug pulling. Developing the Shed-It gave me a solution for dealing with my own scrap problems but I also thought if I could help just one other company, that would be great.”

Rotor Clip initially bought 1,000 Shed-It devices then purchased an additional 2,000. Currently, the company has 3,000 devices. The real test of an innovation sometimes can be seen in its ability to adapt to new situations. “We don’t use the Shed-It the way Dick does, but he said he thought it would work for us and it did,” says Grinthal. FFJ

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Sources

  • Crystal Engineering Co. Inc.
    Newburyport, Mass.
    phone: 978/465-7007 
    fax: 978/465-9977 
    www.crystalengineering.com
  • Rotor Clip Co. Inc.
    Somerset, N.J.
    phone: 732/469-7333
    fax: 732/469-7898
    www.rotorclip.com

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