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A proud Allison business
Member since 1977, Automotive and Commercial Castings
Converting from iron to high pressure aluminum die casting to lighten vehicle weight
Used in John Deere Compact Utility Tractors, including Model 3033R
Transmission case
TMA, a joint venture between John Deere and the Japanese tractor company Yanmar, builds transmissions for John Deere utility tractors.
The original transmission case was poured from cast iron using the sand cast process. It had a high price due to its thick walls, slow casting process, slow casting cycle times and poor casting tolerances that required a lot of finish machining.
TMA selected Walker to handle production of the new aluminum case based on our engineering experience and 3,000-ton die-cast machine, which could handle production of large aluminum cases. The goal was to reduce component cost, improve tolerances and achieve the strength and toughness needed for the demanding utility tractor application.
Art to part innovation: Traveling to TMA’s new startup in Rock Hill, South Carolina, Walker engineers collaborated with engineers from Kanzaki, the transmission division of Yanmar, to design the case for the high pressure aluminum die casting process. We worked together for more than nine months to optimize the design.
Designing for strength: The new casting, the anchor for various attachments, has an important role in the function of the vehicle. It must withstand repeated cyclic loading experienced in utility tractor applications. The Walker team used casting simulation to design gating and cooling to yield a high integrity casting.
Designing the transmission case for aluminum die casting reduced the casting weight, resulting in reduced raw material content and a lighter assembly, all leading to a lighter vehicle. Many features that had been previously machined are now used as-cast. Altogether, the conversion from iron to aluminum resulted in lower cost per piece compared with other processes. The project was so successful, TMA now works with Walker on all its large transmission cases.
