A Look Back at the 20th century.

Part 2

Vertically-Parted, Flaskless Green Sand Molding

The 20th century proved to be the most revolutionary in metalcasting's history. With the dawn of the new millennium and as a tribute to the people and technological innovations that have shaped our industry's past, present and future, modern casting is taking a look back at some of the most important contributions of this century.

The words "revolutionary development" may often be tossed around with a high frequency, but few foundry industry historians would question that the entrance of vertically parted, flaskless green sand molding in the mid-1960s is worthy of that designation. This technology allowed foundries to more economically produce castings at higher productivity levels, while delivering closer dimensional tolerances and superior casting surfaces compared to other processes of the time. Until this innovation, said Don Brunner, retired founder of Waupaca Foundry, most green sand molding "developments" were simply doing the same thing in a slightly different way.

In a 1983 paper presented at an AFS green sand technology conference, Richard Stack noted that the process' radical departure from traditional molding caused it to be considered a maverick and to be looked upon by foundrymen of the time with some skepticism. "This maverick process produced high-density green sand molds with vertical parting lines that booked together to form a long, straight, horizontal stack. The molds also were flaskless and required no pouring jackets, weights or bottom boards. Furthermore, the complete gating system, including the pouring basin and downsprue, were permanently mounted on each pattern. The gating system in the mold was fixed in a vertical position common only to vertically parted shell, permanent and semipermanent molds. For the majority of foundrymen who had never seen anything but horizontally parted green sand molds contained in flasks, this was indeed a monumental departure from conventional thinking over the previous 5000 years of metalcasting technology.

Today, the vertically parted green sand method is employed by about 1300 foundries, with most of the capacity existing in Western Europe. In the U.S., this method represents nearly 2 million tons of shipments for gray and ductile iron alone (1.5 million in gray iron and 1.3 in ductile iron).

Offerings to the Industry

The impact of this new development was profound. Ezra Kotzin, the longtime AFS Vice President of Engineering Services, had understood the advantages that vertical molding could offer as a result of his work with vertical shell molds. "Besides the very unusual and interesting concept of the vertically parted green sand mold, we had never seen a machine like it. It was like a Swiss watch. This process spurred a total re-education that included gating, housekeeping, hydraulics, maintenance, etc."

According to Stratecasts' Ken Kirgin, the early adopters of the method soon started to see manhour per ton improvements of 50% or more as their lines filled to capacity. "It fostered the reduction of cleaning room costs because foundries were able to reduce or eliminate parting line flashing that required grinding." Added longtime industry consultant Norris Luther: "The method was capable of producing castings that required no significant post-handling--you could put a cooling line on the machine, integrate continuous blasting and then have a worker snag the parts and toss them directly in the tub for shipment."

Kotzin said this development opened the door to the dimensional tolerance control needed for near-net-shape castings. "Far better dimensional tolerances were feasible by the more uniform mold hardness, compaction and better casting finish."

Jeppesen: An Innovator

The son of a machine dealer, Vagn Aage Jeppesen worked for a year at Vald Birn foundry in Hostelbro, Denmark, after completing his bachelor's education. During his brief tenure at the foundry, a trip taken with Richard Birn to discuss technical issues with foundrymen in Germany had planted the seeds for envisioning a new way of producing green sand molds.

After joining the Den Polytekniske Laereanstalt (Technical University of Denmark) as a faculty member, Jeppesen became involved in government-funded initiatives to develop commercial improvements for Danish industry. Recalling the problems expressed during his brief time in the foundry, he focused on a molding process that could increase production, achieve better product quality and improve foundry work conditions. After creating a prototype of a machine in the university's workshop, Jeppesen ran trials at Denmark's TASSO and Ringe foundries in 1957. In 1959, the 40-year-old university professor was granted a patent on a new molding machine. That first machine is showcased today at the Hostelbro Museum in a special foundry exhibit.

Incidentally, Jeppesen also is credited for other "revolutions," including the practical development of the kidney dialysis machine in cooperation with The State Univ. Hospital in Copenhagen.

A New Equipment Supplier

Founded in 1900, Dansk Industri Syndikat (DISA) had specialized in arms production for nearly its entire existence. At the end of the 1950s, the firm's new managing director, H.K. Jorgensen, was commissioned with the task of finding new civilian business Areas for the company. Brief attempts with baby carriages and motorcycles met little success. Then Jorgensen heard about a foundry molding machine patented in Copenhagen, and the firm bought the patent in 1961.

A team of six engineers rushed to develop a working machine for introduction to the foundry world at the 1962 GIFA Foundry Trade Fair. At one point, the introduction looked doomed. On the eve of the exhibition, a valve shaft broke off. Thanks to a Rein Metal turner who agreed to machine the part through the night, the new shaft was finished at 4 a.m., and the machine was up and running when the exhibition opened.

The first machine, with a potential output of 240 molds/hr, was delivered in January 1964 to United Danish Iron Foundries at Frederiksvaerk, Denmark.

Penetrating the U.S. Market

The first machine (serial number 64.002) installed in the U.S. was at Modern Metals Foundry, Bloomington, Minnesota. The machine [still running for aluminum jobs in very low quantities (50-100 castings) for the railroad signal market] was an odd first installation for the unit, said Don Moonert, President of Disamatic (1983-94) in that the foundry used it very differently than Jeppesen had envisioned. "Modern Metals certainly was a pioneer, and embracing the new molding method was a very innovative move for such a small foundry."

Describing the decision to go with the largely unproven concept, Modern Metals President Jack Rolstad said, "Ordean Egland (deceased company founder) liked to try new things, and he bought it right off the exhibit floor at the 1964 AFS Foundry Convention in Atlantic City." Rolstad, who started at the plant that same year, recalled Egland saying he'd build a separate building for it. If it didn't work, he'd lock up the building so he wouldn't have to look at it. But deep down, he knew that somehow, someway, he could make it work."

Initially, the foundry took work from its squeezers and put them on the new machine. "There weren't any jobs waiting for it, so we had to talk people into them." In addition to Modern Metals, two of the other first five foundries to purchase a machine still are in business--America Magotteaux, Pulaski, Tennessee ('65), and Lodge Manufacturing ('65), who recently replaced four older lines with two new machines. Other pioneering foundries included Intermet-Havana (then Atwood Vacuum Machine Co.) in '66 and Auburn Foundry in '67.

Probably the most critical installation for the U.S. market, however, was Waupaca Foundry in early '67. Moonert recalled that he saw the machine for the first time when he visited Waupaca as a Shalco salesman in the late '60s. "Don Brunner told me that this machine is going to change the industry," he said. "Incidentally, many of the other large foundry companies in Wisconsin were certain that the investment in this machine would mean the end of Waupaca Foundries. They thought this small squeezer shop was crazy for buying in to this fancy new way to make molds."

"My partner, Cliff Schwenn, and I had stack molding experience, so we were familiar with vertical gating systems," said Brunner. Today, the process is employed exclusively (20-plus lines) at all six Waupaca plants in Wisconsin, Indiana and Tennessee, and the foundry runs some of the world's largest patterns. The group also engineers and builds its molding lines in-house.

The biggest technical hurdle dealt with the more demanding sand control required. (Brunner also recalled how he and his partner handled the troubleshooting process: "I bet him a new hat that I could handle the shift problems and he'd handle burn-in. I won the hat.") Brunner said there also was some customer dissatisfaction with the new process, and some automakers didn't believe in the concept initially. "We started with lawn and garden parts, and eventually could show the automakers what the process was capable of."

The machine was assisted by great timing that kept the invention from being shelved for being ahead of its time. "One of the primary reasons for the dramatic growth," said Peter Sorensen, Georg Fischer Disa, "was the strong expansion of the auto industry at that time, which boosted the demand for molding machines with large output capacity."

"A few entrepreneurs felt the new method had potential and they found extraordinary success from it," said Moonert, noting that the most successful foundries in the world are using vertical molding today. "Some started with next to nothing and became successful because they perfected it."

Downstream Effects

The concept was revolutionary in that it not only changed the way molds could be produced, but also other foundry support areas. "It had a big effect on the automation of pouring," said Kirgin. "The ladle now could be held stationary as molds indexed on the line underneath it. This spurred the usage of laser pouring and other technologies." He also noted that large volume sand systems and polyurethane tooling also were areas that were spurred on by the machine.

In addition, said Kotzin, this technology forced the industry onto the cutting edge for sand control and sand testing. "Totally new process controls were demanded and had to be adhered to, since this new process wouldn't tolerate the latitude that the industry had grown accustomed to." Benefits of extended cooling times also became evident by foundries utilizing the method.

Vertical Molding Today

While the vertically parted, high-density molding concept has remained constant, numerous enhancements have been added by manufacturers over the past 35 years. Today, several firms offer vertically parted machines. Some of the advancements on today's machines include increased molds/hr, improved mold quality, larger mold dimensions, automatic mold conveying, coresetting, pattern changing and programmable logic controls. Productivity levels of 400-500 molds/hr with mold accuracies of 0.1 mm or less now are being advertised.

Kirgin expects vertically parted green sand molding shipments to increase to 2 million tons and 1.7 million tons, respectively, for gray and ductile iron in the U.S. over the next 10 years. Growth also is forecast for Eastern Europe and India.

The next push appears to be for aluminum, perhaps the next frontier to be crossed in high-volume green sand production. Currently, only a handful of U.S. foundries are pouring aluminum into high-volume, vertically parted green sand molds.

Looking back on the history, Moonert said, "It was an uphill battle that involved proving the world wrong. People didn't think you could produce molds in a vertical arrangement and set cores--horizontal was thought to be the only way. The Danes thought it was possible but maybe weren't sure themselves when they started off. But once things got started, a number of foundries helped develop this process on their shop floors."