EFFECT OF TIGHTENING SPEED ON THE TORQUE TENSION

EFFECT OF TIGHTENING SPEED ON THE TORQUE – TENSION AND WEAR PATTERN IN THREADED FASTENERS Dr. Sayed A. Nassar, Advisor Saravanan Ganeshmurthy Objective Experimental investigation to determine the effect of the following parameters on the Torque – Tension relationship and Wear pattern in threaded fasteners Head Socket Load Cell • Variable tightening speed DC Motor • Repeated tightening and loosening • Coating • Effect of Variable Interactions Nut Rotary Torque Sensor/ Angle Encoder Nut Factor vs. Tightening Speed for Unlubricated Zinc Coated Fasteners Nut Factor vs. Tightening Speed for Lubricated Zinc Coated Fasteners Wear Track on the Washer Surface Roughness Data for Unlubricated Zinc Coated Fastener and Washer Surfaces tested at Tightening Speed = 1 RPM and 100 RPM Bolt Shank End Hole Side Wear Track on the Fastener Underhead Surface Roughness Data for Lubricated Zinc Coated Fastener and Washer Surfaces tested at Tightening Speed = 1 RPM and 100 RPM Results • Nut factor K significantly increases for tightening speed greater than 30 rpm for unlubricated zinc coated fasteners • Nut factor K significantly increases with repeated tightening and loosening for unlubricated zinc coated fasteners • Lower tightening speeds increase the surface roughness of unlubricated zinc coated washers • Lower tightening speeds and repeated tightening affect the wear pattern significantly for unlubricated zinc coated parts