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AFS coldbox binder reflects on technological change.

AFS Coldbox Binder Conference Reflects on Technological Change

The two-day coldbox binder conference, held in Novi, MI, attracted some 150 foundrymen from around the world to hear a series of technical presentations on coldbox technology and to view first hand that technology's implementation.

At issue were standards for raw material processing, consideration of the core-and moldmaking and handling processes, tooling and related molding and pouring processes.

The coldbox process used for producing cores for metal castings is now a mature and successful technology that is safe, quick and reliable. It wasn't always that way, said Anton Dorfmueller, retired group vice president, Foundry Products Div/Ashland Chemical, who recounted the search for ways to improve a coldbox system brought over from Germany after WW II. Dorfmueller is currently a consultant to several foundries and foundry service organizations.

In his keynote speech to foundry operations personnel attending the first International Coldbox Binder Conference sponsored by the American Foundrymen's Society, Dorfmueller compared the long, costly process of manufacturing cores for metal castings 35 years ago to the mere seconds now required to do the same job.

Dorfmueller told of early coldbox trials, citing a system he and several colleagues devised that was promising enough to attract the attention of Ford Motor Co's Research and Development Laboratory. The lab's tests seemed to validate the efficiency and effectiveness of the group's new coldbox system, until the day that fumes from the activator gases escaped and seeped into nearby Ford executive offices.

"The smell was so bad that most of Ford's top management were driven from their offices, and adjacent offices quickly emptied," Dorfmueller recalled. "Worse, the fumes badly corroded all of the building's decorative brass work. That episode ended the lab's coldbox interest. The project was closed down, and it was back to the drawing board for us."

At that time, many foundries used the hotbox coremaking system. The German [CO.sub.2] cured sodium silicate binder system was tantalizing in that it showed the immense advantages coldbox systems could bring to an industry fighting rapidly increasing costs.

The failure at Ford, he said, gave added incentive to the search for a better method of developing a fast-acting core sand/binder mixture. His failed system required two minutes to cure an average-sized core, a remarkable advance, but he was looking to reduce that to seconds.

A subsequent world tour made him aware of the immense size of the global market that would exist for a truly successful coldbox system.

There followed several aborted attempts to develop a chemically safe, inexpensive, fast coldbox coremaking system and it took three tries to get a good one. It was a gas-curing process that met most of the prime objectives for productivity, materials and cost. Developed by Dr. Janis Robins, it involved a new, highly reactive phenolic resin and polymeric methylene diphenol isocyanate (MDI) coated on the sand and gassed with triethylamine (TEA). In seconds, the process produced strong cores containing only 2% total resin. Though not yet perfect, the cores were dimensionally stable, physically strong and released well from the corebox. The patented process was introduced with much fanfare to the foundry trade at the AFS Casting Congress in 1968.

With some changes in corebox design, blowing and venting techniques and sand adjustments, plus a new gas, dimethylethylamine (DMEA) that reduced the curing time by a factor of three, the coldbox coremaking system began to attract foundry industry attention. By the mid-1980s it had become the most widely used system. In applications where coldbox coremaking made economic and production sense, it began to replace other more traditional processes.

Additional acrylic and epoxy systems have since joined the original phenolic urethane system to further improve cure speed and high hot strength. Also new, he said, is an automated coldbox line that takes in sand and core binder and delivers assembled, washed and dried finished cores to the molding line.

Dorfmueller also commented on a new [CO.sub.2] corebox blast cleaner introduced at the 1990 Cast Expo in Detroit. It allows cleaning coreboxes while they remain in the molding machine.

He noted that the next logical step in speeding the coldbox production line is to incorporate a cleaning system within the coreblower. This would allow completely automatic operation by eliminating corebox changeover operations just for cleaning, Dorfmueller said. He reported that many of the elements of an automated core production system are in place in Europe, and he urged North American foundry engineers to complete the task.

In addition to Dorfmueller's keynote address, the conference also featured seven other presentations that covered a variety of technical and production advances in coldbox binder systems.

A special attraction of the meeting was a tabletop exhibit of coldbox binder products and processes.

PHOTO : Anton (Tony) Dorfmueller, Jr. was the keynote speaker at the first International Coldbox Binder Conference held in Novi, Ml.

PHOTO : The tableop exhibition room was a major attraction of the coldbox binder conference.
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Title Annotation:American Foundrymen's Society conference in Novi, Michigan
Author:Bex, Tom
Publication:Modern Casting
Date:Aug 1, 1990
Previous Article:Pattern determines construction materials.
Next Article:Globe Metallurgical to license Inmold, Flotret processes.

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