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Walker Die Casting P.O. Box 1189, 1125 Higgs Road Lewisburg, Tennessee 37091
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TMA Transaxle Manufacturing of America

(John Deere + Yanmar)

Converting from iron to high pressure aluminum die casting to lighten vehicle weight.

The Part

UT 20 Transaxle Assembly for 3000 series John Deere Tractor Models

Used in John Deere Compact Utility Tractors, including Model 3033R

  • Alloy: A380
  • Weight: 61.75 lb.

The Challenge

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.

The Solution

Print 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.

The Result

The Walker engineering team collaborated with TMA to redesign the transmission case to be manufactured through die casting versus sand/perm mold, resulting in reduced raw material content and a lighter assembly, all leading to a lighter vehicle. 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.

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Ongoing partnership
Lighter vehicle
Improved tolerances
Minimized machine stock
Reduced machining
Reduced cycle times
Lower cost per piece