Durability and performance evaluation of surface treated worm drives of similar material pair

The present work is concerned with development and analysis on the performance of a similar material pair worm drive. Experiments were carried out on En-353 steel, case hardened worm mating with Sursulf treated wheel made of the same material. A constant value of limiting torque has been established at all tested speeds. It is found that at higher speeds (>1200 rpm) temperature increases progressively without attaining a stable value, leading to thermal instability. Beyond this, lubrication failure has been observed. Efficiency is relatively higher at intermediate torque levels. Reduced efficiency at higher torque level is due to ineffective lubrication. From the wear debris analysis, it was observed that no uncharacteristic mode of wear prevailed at any of the tested conditions. A fairly low value of coefficient of friction based on operating conditions is observed. This can be attributed to the presence of Sursulf treatment. The drive has not exhibited any tendency to scuffing or scoring within the range of tested conditions for continuous duty, largely attributed to Sursulf treatment.