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FALL 2017

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Distributor's Link Magazine Fall Issue 2017 / Vol 40 No4


42 THE DISTRIBUTOR’S LINK Michael Mowins Michael Mowins is the President-Global Licensing for Phillips Screw Company. He is the author of numerous articles on innovation, assembly, and quality. He has served as Associate Chairman for the National Fastener Distributors Association, Chairman for the Industrial Fastener Institute’s Associate Supplier Division, and Chairman of the Aerospace Fastener Standards Advisory Committee. He serves on the SAE E-25 Engine Bolt, EG-1B Hand Tool, and G-21H Counterfeit Hardware Committees. He holds 4 U.S. Patents and is a graduate of the U.S. Naval Academy (BS) and University of Rhode Island (MBA). MAXIMIZING DRIVER TOOL CONTACT TO OPTIMIZE FASTENER INSTALLATION AND REMOVAL There have been many approaches to solving the problems associated with efficient torque transfer between the tool and the fastener. Understanding the importance of driver tool contact area is leading to the evolution of better solutions. Since the first threaded fasteners were introduced, designers have been searching for the most efficient way to impart torque to the fastener to twist the threads into the mating nut, or form threads in the base material. Efficient torque transfer is critical in providing either the power needed to form threads in the mating material, or to achieve enough loading between the mating threads of the fastener and nut to achieve the needed clamp load to assure a secure joint. The original slotted screw and driver provide only two thin lines of contact at the outer edge of the driver blade as the area through which the rotational torque is transmitted. Problems with the slotted driver damaging the head of the screw led to better recess and driver combinations like the Robertson square and the original Phillips cross recesses that provided four areas of contact and improved the torque transfer. Externally wrenched bolt heads had the same issues. The original square head bolt provided only four lines of contact at the corners of THE ASYMMETRIC SHAPE AND LOCKING RIBS OF THE ACR® TORQ-SET® DRIVE PROVIDED IMPROVED REMOVAL CAPABILITY FOR AIRFRAME MAINTENANCE. the square head when a square socket was twisted into engagement. Evolution of fastener drive systems primarily focused on how to improve the number of lines of contact between the tool and the recess or bolt head. Square bolt heads evolved into six sided hex heads providing six lines of contact between the bolt head and the socket. The hex head then evolved into the twelve pointed bi-hex heads based on the design philosophy that “more is better.” Added engagement area between the socket and the bolt head could also be achieved by making the bolt heads taller and the sockets deeper, thus increasing the length of each line of contact; but, unfortunately, also increasing the weight of the bolt. The same holds true for the evolution of the fastener recess where the square drive led to the hex socket and finally to the twelve point socket used by some European auto makers. Increasing the line of contact length holds true for recess head fasteners as well which results in socket head cap screws being taller than pan head fasteners with the same hex recess. The deeper socket provides longer lines of contact between the socket and the hex key providing the needed torque transmission capability to achieve the needed clamp load in high strength cap screws. CONTRIBUTOR ARTICLE CONTINUED ON PAGE 146

THE DISTRIBUTOR’S LINK 43 Askew Industrial Corporation, CAGE Code 5A195, is proud to announce the launch of our e-commerce site for Mil-Spec fasteners - our new site at www. now allows you to order online at your convenience and have Mil- Spec fasteners shipped the same day! We stock the largest Mil-Spec inventory in the country. Our domestic and DFAR inventory is strategically located throughout the United States and ready for same day shipment. Specials and standards off-theshelf with full lot traceability. Hex Bolts, Lock Nuts, Nuts, Washers, Full Thread Studs, Double End Studs, Socket Heads and Specials. All specifications MIL-S- 1222H, MIL-DTL-1222J, MIL- N-25027, ASTM F467/F468, NASM25027, FF-S-92, FF-W- 92, FF-S-86E, FF-W-84, QQ-N- 281, QQ-N-286. Material grades 400 Monel®, K 500 Monel®, 300 Series Stainless Steel, 316 Stainless Steel, Grade 5 Steel. Complete certification packets along with full dimensional inspection reports are available with every order. For more information, contact Askew Industrial Corporation at 13071 Arctic Circle, Santa Fe Springs, CA 90670. Tel: 1-800-322-7539, Fax: 323-726-3462 or Email: To order today please visit www.


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