WINTER 2023

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36 THE DISTRIBUTOR’S LINK Larry Borowski President GREENSLADE & COMPANY INC. 2234 Wenneca Avenue, Fort Worth, TX 76102 TEL 817-870-8888 FAX 817-870-9199 EMAIL sales1@greensladeandcompany.com WEB www.greensladeandcompany.com IF YOUR PRODUCT DOES NOT PASS THROUGH A GO THREAD RING GAGE, NO PROBLEM... Often I receive calls from threaded fastener suppliers asking me if there is an inspection rule for the acceptance of bolts and screws that do not freely enter a GO thread ring gage. Furthermore, the word “freely” is very subjective, and can mean a wide variety of things to different people. These questions generally arise with threaded products that are plated or coated, and/or have slightly nicked threads. Fortunately, there are a few international standards that are in agreement on this issue. These standards are: ¤ ISO 6157-3. ¤ DIN 267, part 19. ¤ DIN EN ISO 26I57-3. In addition to these three international standards, Ford Motor Company has adopted the same criteria in its standard WA-990, published in 1993. These standards present the same formula for calculating the acceptance torque values. The formulas for deriving the maximum allowable Go thread ring torque values are as follows: For inch parts: T = 145 x d3 T = maximum torque in in-lb d = nominal diameter in inches These formulas can be applied to any size thread. The chart below contains the computed and rounded torque acceptance values for the most commonly used inch and metric thread size ranges. For metric parts: T = 0.001 x d 3 T = maximum torque in Nm d = nominal diameter in mm TECHNICAL ARTICLE CONTINUED ON PAGE 108

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