Case Study: Defense Industry

Plastic Injection Solutions for the Defense Industry

Support Arm Bushing Modifications

Plastic Injection Solutions for the Defense Industry

The Australian Defense Force (ADF) was in search of a material that would not wear down or damage the support arm trunnion of the M113 armored personnel carrier.

The current bushing material was causing excessive wear and frequent repairs. The M113’s needed to take heavier loading, tolerate higher speed and last more than 10,000 km.

The application conditions where the support arm bushing was engineered to survive were:

  • Vehicle weight under normal operation: approximately 10 to 13 metric tons for all variations.
  • Maximum combat laden weight: 13 metric tons.
  • Vehicle speed: Max at 75 kn/hr (45 mph) on open road.
  • Temperature: -40°C to 150°C.

Plastic Injection Solutions for the Defense Industry

A unique blend of lubricated PEEK was developed and processed resulting in the following results:

  • Of six materials tested, the Ames team material was selected.
  • Actual vehicle testing was conducted after which the trunnions were in “almost perfect condition.”
  • Estimated life of the bushing was twice the desired specification.

Modifications to this support arm bushing are also fielded in the STK Bionix vehicle (27 ton infantry fighting vehicle) and the AMX 13 SM1 (17 ton light tank).

Race Bearing Modifications

The supplier of a shock strut for a foreign Armed Force organization approached the Ames team requesting modifications to the existing design of a Race Bearing to increase its life expectancy. The design was considered carefully as well as the current material used. Based upon the analysis, some design changes and material changes were suggested and ultimately prototyped and tested. The material was changed to a high performance PEEK polymer. The geometry of the bearing was also changed. The bearing has a very tight tolerance requirement to achieve the correct fit while maintaining the correct running clearances. The result of the activity was the development and fielding of a new race bearing with 3X life expectancy. Because the part is injection molded without the need for significant secondary operations, the acquisition costs are very competitive.

The fielded race bearing (mounted on the ball).

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