Site: Yamagata Seimitsu Chuzo Co., Ltd. 768-2 Narita Hachiman Nagai City Yamagata 993, Japan Date Visited: January 10, 1996
WTEC Attendees: T.S. Piwonka (report author), H.W. Hayden
Hosts: Nobuyoshi Sasaki, Chairman of the Board Susumu Baba, President
Yamagata Seimitsu Chuzo Ltd. (YSC) is the production foundry established by Mr. Sasaki, who is also president of CADIC Corp., which the WTEC team visited as well. The foundry uses the CADIC investment casting process and was originally established to train licensees in that process. It has since become a production foundry, which is today the 12th largest investment foundry in Japan according to sales dollars. It ships 15% by weight of all investment castings made in Japan.
Research and Development activities are carried out by CADIC Corp. This foundry is still a training site for CADIC investment casting licensees and could be used as a site to train foundries that use the CADIC Convert Mold process, which grew out of the investment casting process. CADIC does not plan to license that process but merely to sell the silicate solution.
The CADIC system is described in a publication (Sasaki 1994), which was presented at the 27th ISATA Conference and was distributed at the WTEC visit to CADIC. It was developed in 1986, based on technology originally acquired from East Germany in 1981. It has been licensed to ten companies subsequently, although a number of those licenses have expired.
At the present time the technology is driven by the material requirements for hotter, more efficient automobile engines and lighter cars. These requirements, in the opinion of Mr. Sasaki, mean that conventional cast iron will be too heavy and will lack the necessary properties to meet the requirements of modern automobiles. Instead, cast iron components must be replaced by alloy and stainless steel. The idea behind the CADIC investment casting system is to bring the cost of investment casting down to a level that is competitive with other manufacturing methods, so that it is attractive to the automotive industry. He sees exhaust manifolds, camshafts, and brake and steering components as potential products.
Mr. Sasaki estimates that the average cost of conventional investment castings in Japan is around ¥5000/kg, whereas in the United States the costs are perhaps ten times lower. The difference in cost is due to higher labor and material costs and energy costs that are three times as high in Japan as in the United States.
The plant has 60 employees and operates one shift, except in dipping, where two shifts are necessary. Patterns are automatically injected and are attached to the downsprue as fast as they are removed from the pattern die (the wax press operator also trees up the patterns on the sprue). The downsprue is a hollow steel tube, which has been dipped in wax. An automated dip line, of very simple but clever design, is used to dip and sand the clusters. Silica sand is used as the stucco; it is obtained locally and is inexpensive. Clusters are autoclave de-waxed and poured manually. Induction melting is used.
The most interesting aspect of the CADIC system is that the castings are fed through extremely small gates. This allows the castings to drop off the downsprue when the ceramic is removed using conventional knock-out (vibrating hammer) techniques and eliminates the need for separate casting cut-off operations. In spite of the small gates, sound castings are possible because the arrangement of castings on the cluster is such that there is a strong thermal gradient established from the outer surface of the casting to the surface near the sprue, which encourages progressive solidification and eliminates shrink. This gradient can be enhanced by spraying water on the exterior of the cluster during casting solidification.
YSC does not use solidification simulation programs to gate castings and also does not use any rapid prototyping technology because the present cost is prohibitive. WTEC team members saw no control charts posted in the dipping area. The team was shown YSC's quality engineering and inspection area and saw that scrap causes were carefully noted and entered into a computer.
YSC recovers heat given up during solidification and uses it for space heating. It has built a special duct that surrounds the solidifying castings and captures the heat. Used ceramic is disposed of by giving it to a rubbish collector. Since disposal of molding material as landfill in Japan is regulated by individual prefectures, the rubbish dealer is today still able to find a nearby prefecture to which to haul the refractory. At the present time it is far more expensive to attempt to reclaim the material than to dispose of it.
As a small independent foundry, YSC representatives indicated that they found it very difficult to hire qualified engineers, particularly out of college. While part of the problem is their location (they are in a small town far away from large cities) and part of the problem is that foundries are not generally considered to be desirable places to work, in Japan the best graduates go to large corporations. If the corporation has a foundry, these graduates may be assigned to it, but small independent foundries find it nearly impossible to recruit engineers.
They also indicated that they believed that MITI was not especially interested in the foundry industry and that one reason that foundry research in Japan is limited is that Japan has no defense industry. Another concern about MITI was that MITI managers change so often that is not possible to educate them properly about the foundry industry in time for them to take action that would help the industry.
YSC managers foresee that foundries will increasingly move from Japan to sites in Southeast Asia, following their major customers who are moving to take advantage of lower land and labor costs and local content laws. They do not foresee that Japanese environmental regulations will force foundries to move from Japan.
N. Sasaki. 1994. "CADIC System: Using Precision Casting Techniques to Produce Thin-Wall Cast-Steel Parts to Reduce Automobile Weight," paper 94NM073, Proceedings of the Dedicated Conference on New and Alternative Materials for the Transportation Industries, 27th ISATA, Aachen, Germany, November, p. 237.