Ultrafast mold change is the tantalizing promise of magnetic mold-holding systems, but whether the technology sweeps through the injection molding industry depends on convincing people like Lonnie Hines.
Today, Hines is a true believer that magnets can safely hold up massive molds on an injection molding machine. The magnets cut the time for a mold change on a 3,000-ton press to about an hour, compared with six hours using bolts and clamps, he said. Suppliers say 10-minute mold changes are not uncommon for smaller molds.
But he was nervous the day that first Tecnomagnete system arrived at the Textron Automotive Co. plant in Westland a few years ago.
``I had never seen one before in my life,'' said Hines. As maintenance supervisor for plastics molding at the plant, now part of Collins & Aikman Corp., he was used to standard, bolted-on molds, or mechanical quick-change systems. He was skeptical when the installation crew said magnets would hold a 10,000-pound mold in the air.
That reaction is typical, according to the three suppliers of magnetic systems for holding injection molds: Tecnomagnete Inc. of Troy, Mich.; StÃ¤ubli Corp. of Duncan, S.C.; and EAS Mold & Die Change Systems Inc. of Butler, Wis. Now, as demands for quick mold changes are boosting interest in magnets, the suppliers say their first job with new customers is simply explaining how magnets - more accurately, electropermanent magnets - work.
These are not refrigerator magnets. On electropermanent magnets, a short burst of electrical power magnetizes the system. To demagnetize, you have to go in physically and turn off the magnets with another short burst of electricity.
Magnetism, not electricity, keeps the mold held fast. So it doesn't matter if the plant loses power. Welcome to Magnetics 101, Lesson One.
```If the power goes off, will it fall off?' That's always the first question,'' said Simon Barton, StÃ¤ubli product manager.
``They're permanent magnets,'' said Cliff Drake, president of EAS. ``They do not rely on power to keep them magnetized.''
For Lesson Two, listen as Hines continues his coming-of-age magnetics story: At the installer's urging, Hines stuck a ball-peen hammer onto the die. The handle stuck straight out. Then he hit the handle with his hand. The hammer fell right down. Now it was time to attach the mold.
``I stepped back. I laughed because I thought it was just going to fall to the ground,'' he said.
But magnets held the massive mold tight. The demonstration showed Hines that the holding force of the magnet is determined by the surface area of the object being held.
While magnets are not used widely by processors yet, automotive molders like Collins & Aikman are early adopters of the technology, the result of customer demand for low inventories and just-in-time production. But magnets now are spreading to the appliance, electronics and other markets.
Tom Erwin, Tecnomagnete's product manager for plastics machinery, said injection molders who change tools three times a week can justify the cost of a magnetic system.
Tecnomagnete SpA is the largest supplier of magnets for injection molding. The Italian company has sold 3,000 magnets total worldwide. Through Tecnomagnete Inc., the company said it has sold 600 magnet systems to U.S. injection molding companies. Tecnomagnete expects to sell at least 250 units to U.S. molders this year, according to Alessandro Chiaramonte, operations manager at the U.S. unit.
As the technology spreads, magnet suppliers are dealing with lots of people like Lonnie Hines. Today, his Collins & Aikman plant, which molds grilles, front fascias and other parts for Chrysler Corp., uses magnets to hold molds on 12 of its 17 Van Dorn Demag presses. The systems, all from Tecnomagnete, are used on presses with 400-3,000 tons of clamping force.
Companywide, C&A now owns 42 magnetic mold systems, all but one from Tecnomagnete, according to David Marten, C&A's director of continuous improvement. That makes the automotive plastics giant the largest U.S. user of magnetic systems for injection molding.
Despite Tecnomagnete's strong numerical position there, StÃ¤ubli and EAS both are aggressively courting the company.
That has led to some friction - especially between Tecnomagnete and StÃ¤ubli. Last November, Marten and John Devic, C&A's director of environmental, health and safety, issued a recommendation, based on company research, that C&A plants buy future magnets from StÃ¤ubli.
But in mid-May, Marten said recent product improvements by both Tecnomagnete and EAS means ``we anticipate they'll be an approved source for magnets also.''
Collins & Aikman does not have any StÃ¤ublis running on production machines - Marten said much of the research was done at another automotive molder. He said C&A expects to receive its first two StÃ¤ubli magnets soon.
Marten, who specializes in error-proofing the company's operations, said Collins & Aikman actually held off buying any magnets for awhile to do its research, mainly on aspects of safety and whether tools can be damaged. There are no current plastics machinery safety standards on magnetic mold clamping, according to the Washington-based Society of the Plastics Industry Inc.'s Machinery and Moldmakers divisions.
``All three suppliers have spent an awful lot of time here and I think, because of the emphasis we've put on it, it's changed the whole industry and made it safer,'' Marten said.
That leads to Lesson Three of Magnetism 101: You can't see it. Remember back in sixth grade? You covered a horseshoe magnet with a white sheet of paper, then tossed iron filings on top. They fanned out in a pattern, clearly showing the lines of magnetic force, or flux.
Magnet suppliers have developed systems that constantly monitor flux, letting you ``see'' the magnet working.
Improvements to Tecnomagnete's Quad-Press system include real-time sensing of the flux. The monitoring system automatically detects the presence of magnetism and changes to the holding force, calculates the area of the mold, measures the quality of surface contact and displays on a screen the total holding power available for that specific magnet on that mold and press.
Tony Firth, vice president and general manager of injection press supplier Sandretto USA Inc. of Freedom, Pa., thinks magnets have a bright future.
``They're perfectly safe,'' he said. ``The biggest hurdle they have to overcome is what I call the short hairs standing up on the back of your neck when you first turn it on. Because it's magnetic force, it's something you can't touch and feel. But it works extremely well.''
Bemis Manufacturing Co., a custom molder in Sheboygan Falls, Wis., has one EAS magnet system on a 725-ton press.
``Because you don't see anything, it's a little bizarre. It's hard to get used to,'' said Pete Bollenbacher, injection molding process manager.
Bollenbacher said Bemis is ``delighted'' with the mold-clamping system, and plans to buy more.
``The nice thing about magnetics, is that we can put any different-sized mold in that press,'' he said.
But Bemis started out slowly.
``We were very cautious at first. I assigned one guy on one shift to do all the mold changes for a period of two months,'' he said. Bemis has not experienced any problems.
All three suppliers have safety systems in place to shut down the press if any problems occur. StÃ¤ubli QMC-121, for example, also makes it impossible to operate the magnet with the press guards open, or during production. The sensing system also detects if an operator makes a mistake when setting up the mold, Barton said.
Safety systems also turn off the magnets during mold changes.
Nobody has been hurt by a mold falling off the magnets, according to all the industry officials interviewed for this story.
Tale of 3 competitors
You can tell the players by the geometry of their magnets. Tecnomagnete's are square, like a checkerboard. StÃ¤ubli favors round magnets. EAS systems use rectangular Pressmag-brand magnets from Walker Braillon of France.
Tecnomagnete has, by far, the most systems in plastics plants. Tecnomagnete and StÃ¤ubli both accuse the other of making misleading statements - often the debate gets into issues of magnetism and physics.
It can get pretty rough-and-tumble between the two firms, as they even dispute each other's unit sales claims. Tecnomagnete's move to reduce prices drew fire from StÃ¤ubli's Barton, who said Tecnomagnete reduced the number of magnets. True, said Chiaramonte, but that was because the earlier version was overengineered with square-pole magnets covering every conceivable surface of the platen.
``We removed those poles that were never used,'' he said.
The retrofit market is huge. All three companies can agree on that. So is the potential for new injection presses. StÃ¤ubli's Barton said about 10,000 new presses a year, worldwide, could be a candidates for magnetic quick-mold-change systems.
More press buyers are asking about magnets, said Michael Urquhart, vice president of service and sales at Husky Injection Molding Systems Ltd. of Bolton, Ontario. ``It's not so much of an oddity. People are looking into the economics of it now,'' he said.
In November, StÃ¤ubli finalized an agreement with press maker Milacron Inc. to be its preferred magnet supplier.
But Erwin said Milacron has supplied presses with his company's magnets, at customers' requests. The Milacron/StÃ¤ubli deal is the only formal machinery maker/magnet supplier partnership so far, although others are in the works.
Returning to Magnetics 101, all magnets have north and south poles, but beyond that, each system uses a different design. Bone up on your magnet knowledge before the competitors come on a sales visit. Meanwhile, here's a recap of the history of each company, and a basic explanation of how their magnets work:
Tecnomagnete. The metalworking industry has used magnets for years - many of them manufactured by Tecnomagnete, a 30-year-old magnet company based in Lainate, Italy, near Milan. Tecnomagnete is a major supplier of electropermanent magnets for holding work in place on metal-cutting machines. Each year the company sells thousands of small magnets to machine shops for lifting and moving metal parts.
``They sell them like candy bars,'' said Jerry Gagnon, sales manager for all products.
As Chiaramonte said: ``We get up in the morning, we think magnetism.''
Tecnomagnete expanded into the injection molding systems about 10 years ago, serving customers in Europe. Erwin said the company first showed magnets to North American molders at the NPE '97 show. But NPE 2000 marked the coming-out party. Erwin said the company had Tecnomagnete magnets displayed on two Van Dorn Demag presses, of 500 and 1,100 tons; a 600-ton Krauss-Maffei; a 1,000-ton Engel, and a 240-ton Sandretto, plus magnets in its booth.
``And they were all sold,'' Erwin said. ``That was the show that really kicked this thing off. I mean, we really started selling magnets left and right.''
Tecnomagnete claims its bi-magnetic magnets have more magnetic force than competitors'. In the square-pole version, or Quad System, the flux is conducted only pole-to-pole; it never goes through the base plate of the magnet or dissipates away to the side, according to Chiaramonte.
StÃ¤ubli. Parent firm StÃ¤ubli AG, based in Zurich, Switzerland, makes a range of products, including robots, textile-weaving machines and quick-disconnect connectors. The firm is known in the plastics industry for robots and quick-mold-change systems.
While Tecnomagnete casts itself as the experienced veteran, StÃ¤ubli's spin is that its magnets are designed especially for injection molding, while Tecnomagnete's reflect more general designs developed for metalworking.
Simon Barton, an Englishman with 22 years of experience in magnets, came to the United States first to work with Erwin at Tecnomagnete. He was operations director from 1994-98, then left to start his own company, Alpha Work Holding in North Carolina. StÃ¤ubli ended up buying Alpha to get into magnets for injection molding.
Barton said StÃ¤ubli makes its own magnets in Germany. But Barton, who designed the injection mold magnet, said the U.S. operation buys its magnets from Sullivan Corp. of Statesville, N.C.
StÃ¤ubli introduced the round-pole QMC magnet at NPE 2000, after launching it in Europe earlier. In 2001, the company sold 125 magnet systems worldwide, about 15 to U.S. molders, Barton said. StÃ¤ubli already has doubled last year's U.S. sales, he said.
StÃ¤ubli uses round-pole technology. Tecnomagnete's Erwin said square magnets use space more efficiently than rounds - a basic fact of geometry - but Barton dismissed that. Tecnomagnete also claims StÃ¤ubli is using 20-year-old Tecnomagnete technology - also denied by StÃ¤ubli.
Why did Barton choose round poles? He said he wanted to be able to cram more poles into a smaller area, while being able to move the poles around the SPI-specified ejector holes, which can be done more easily with round shapes. Also, he said, ``our poles are self-contained island poles,'' which gives StÃ¤ubli flexibility in the arrangement of magnets, unlike competing systems that combine separate poles into a separate magnetic circuit.
``We are not limited to exact spacing of poles like our competitors,'' Barton said.
EAS-Walker Pressmag. EAS was formed last year through a management buyout of Enerpac Automation Systems. The company now buys magnets made by Walker Braillon in Montmelian, France. They are easily identified by their rectangular shape, long and skinny.
``The long poles give us essentially stronger holding force,'' said EAS President Cliff Drake. The geometry also makes it easier for smaller molds to cover more magnets - and get a stronger holding force, he said.
EAS, like StÃ¤ubli, also offers mechanical quick-mold-change systems.
Drake did not release the number of magnetic systems EAS has sold. But he said molders are driving demand once they learn the technology.
``We're still doing what I would call missionary work on it. Some people aren't aware of it, or some people aren't comfortable with it. They don't have a lot of experience with it,'' he said.
EAS sells three versions of Pressmag systems. The Pressmag HP, which stands for high power, is available as a basic magnet system for presses with more than 300 tons of clamping force. The other models, the Pressmag T and HT, retain their magnetism at high temperatures.
Pressmag magnets use the back plate of the tool as well as the magnet. The long-pole design enhances the concentration of flux, Drake said.
The high-temperature performance makes the EAS mold-change system good for injection molding thermoset plastics or silicone rubber, Drake said. EAS is targeting thermoforming for that same reason.