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FALL 2022

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Distributor's Link Magazine Summer 2022 / Vol 45 No 4


52 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 WEB LET’S TALK ABOUT TORQUE Even with all the published information out there on the subject of Torque, I continue to get calls quite frequently for help and/or guidance in this area. Probably the most frequent question I get is, “What torque should I use for my fasteners”. The simple response is, “It depends on your application”. You can search the internet and find a ton of “Torque Charts”, and if you actually read the fine print, you will discover that these charts are general guidelines that apply only to the bolt or screw. In addition, they are of particular material and certain assumptions are made that the mating part is of the same strength material. Not only that, but friction created by surface condition in the assembly is broken down to a theoretical number. These charts do not account for fasteners going into a softer material than the bolt, and should really only be used for reference. The best way would be to develop your intended torque through experiment, which we will get into later. In the absence of a chart to provide a starting reference torque, you can easily do the math yourself. The most commonly used Engineering TECHNICAL ARTICLE formula to determine torque is the following: T = TDK, where T = Theoretical Target Tightening Torque D = Nominal Diameter of the Fastener K = “K” factor or friction factor ¤ This K factor can vary from .1 to .4 depending on the surface condition. The most commonly used factor is .22 for zinc plating on fasteners. P = Desired Clamp Load ¤ This number is typically 75% of Proof Load or Yield Strength of the fastener. ¤ You can also derive this number using the thread tensile area and the yield strength of the fastener material (also take 75% of the result). As stated above, this will provide you with a good reference torque that should be close to the optimum torque for your particular application. Where it could change dramatically, would be if the mating thread was of different strength than the bolt, or your assembly includes gaskets, or brittle materials. In these cases experimentation would be highly recommended. The failure mode occurs when any one component fails, not only the fastener. CONTINUED ON PAGE 144

THE DISTRIBUTOR’S LINK 53 Copper State Bolt & Nut Co. is expanding its 50-year presence with a new Class A distribution center in Goodyear, Arizona. Founded in Phoenix in 1972, Copper State today employs almost 500 and supports more than 20,000 customers across the West and Southwest. It provides traditional fasteners, construction products, industrial supplies and specialty products to constructionand manufacturing related industries. “We have spent 50 years evolving to support our fastpaced, service oriented industry, and our latest expansion is no exception,” said Copper State CEO Sarah Shannon. “This new facility expands our reach farther into Phoenix’s West Valley than we have been before, where so many of our customers are building and operating in response to a nearly unprecedented commercial and residential boom. With our location, we will be right where they need us to be.” Copper State operates more than 30 facilities in Arizona, California, Colorado, Montana, Nevada, New Mexico, Texas, Utah and Washington. Ten of those are in Arizona, including the company’s manufacturing and assembly headquarters. For more information contact Copper State Bolt & Nut Co. by Tel: 1-800-603-6887, email: or at


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