shrink-fitting an assembled wrist pin into a connecting rod

Objective

Shrink Fitting an Assembled Wrist Pin into a Connecting Rod

End Product

Wrist Pin

Equipment

Ambrell EASYHEATTM 4.2 kW, 150-400 kHz solid state induction power supply with a workhead and coil specifically designed for this application.

Materials

Rod has an OD of .9125” (23.18 mm), knuckle has an ID of .9125” (23.18 mm) with an interference of .0001” (.0025 mm). Knuckle assembly is forged steel.

Temperature

400 ºF (204 ºC)

Frequency

210 kHz

Testing

A six-turn helical coil was used to heat the connecting rod for 13 seconds. The coil was perpendicular to the axis of the bore to promote even heating around the circumference. The connecting is assembled with the piston for shrink fitting. 

Benefits

Induction heating offers this application:
• More accurate control of heat vs a flame burner. Induction only heats the knuckle, not the whole part.
• A lower temperature was used to prevent discoloring.
• Increased productivity due to repeatability and ease of operation. A foot pedal and timer was used.
• No product contamination

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