One of the most recent developments in Japan has been the manufacture of titanium alloy golf heads using investment casting techniques.
This development is rather rare because over 70% of the metal cast in Japan is produced for the automotive industry. Also the investment casting area has had the greatest number of new products. Since the automotive industry in Japan is highly driven by cost, many product applications add value to the automotive producer.
Some examples of new products are a 390 aluminum alloy closed deck block produced by Toyota (see Fig. 5.1). This product required development of a new casting process to produce it in a metal mold with sand cores. Toyota refers to this process as a differential pressure casting process. The casting is characterized by its many cast-in features that are too complex for typical high pressure die cast, semipermanent mold, or sand casting techniques. This engine powers the Lexus car.
Fig. 5.1. Toyota V-8 cast aluminum 390 alloy engine block (Toyota).
Another significant product development in Japan has been the aluminum cast auto wheel. Both Ube Industries and Toyota produce these wheels using a high pressure casting technique they call squeeze casting (see Fig. 5.2). In this technique 356 aluminum alloy wheels are produced in metal molds under high pressure. The aluminum is placed into a shot sleeve, which fills the metal mold at a relatively slow rate when compared to high pressure die casting. This technique of casting is also used to produce various chassis components such as control arms, steering knuckles, brake components, and suspension modules. The number of new products produced using squeeze casting still remains small when compared to high pressure die casting in Japan. The major potential remains in moving from nodular iron components to aluminum to save weight. Cost pressures, however, continue to be the prime driver, and the shift to aluminum has slowed greatly.
Products from magnesium materials were discussed at nearly all locations. Prototype products were shown or mentioned, but no new products were shown to our team. Again, cost was the primary reason that magnesium was not being developed further into new cast products. Some examples of cast magnesium products from high pressure die casting are VCR cases, travel cases, and computers.
Fig. 5.2. Aluminum squeeze cast wheel (Toyota).
As mentioned earlier, investment casting of golf heads remains a growth industry, but the sales volume is very small compared to high production automotive products. This industry does produce many high value products in Japan and is looking to expand into the automotive market by manufacturing rocker arms (see Fig. 5.3). The industry currently is aerospace-, defense-, and machine tool-based (see Fig. 5.4).
A recent product development by Hitachi Metals is a cast stainless steel exhaust manifold using a vacuum-assist gravity pouring technique.
Fig. 5.3. Varied investment auto and sport casting components (NPC).
Fig. 5.4. Investment cast aerospace and defense components (NPC).
Published: March 1997; WTEC Hyper-Librarian