Ausform Finished Powder Forged Gears - A Process Capability Study

摘要

Powder metal (P/M) technology has the potential for substantial cost advantage for high volume vehicle transmission applications as compared to current wrought or forged steel parts. Although a wide variety of P/M components are currently in production in the automotive industry, application of P/M steel gears for more heavily loaded transmission has been limited. P/M gears possess adequate tooth bending fatigue strength, as well as reasonable performance in roller on roller rolling/sliding contact fatigue testing conditions. [1-14] However consistent and adequate gear on gear surface durability performance in terms of pitting fatigue and wear resistance under high rolling/sliding contact stress conditions has not been demonstrated. An experimental study was carried out that demonstrated surface durability, bending fatigue strength scoring and impact resistance of ausform finished powder forged (P/F) gears to be equivalent to or better than current wrought steel gears. A detailed process capability study was carried out based on a mini production run of about 1.700 parts, and this paper summarizes the results of statistical evaluations for multiple gear accuracy parameters.