FALL 2023

46 THE DISTRIBUTOR’S

46 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 6e AND 6E PITCH DIAMETER ALLOWANCES PROVIDE SPACE FOR HEAVY COATINGS Many of the newer, high-performance corrosionresistant finishes are thicker than older standard fastener finishes such as commercial electroplated zinc with clear or yellow chromate. To achieve equal corrosion resistance, the new finishes containing trivalent chrome are applied thicker than the hexavalent chrome finishes they are replacing. The heavier application of finishes on threaded fasteners results in more problems related to thread interference in assembly. Thread fit cannot be ignored when high performance finishes are required. The design and manufacturing solutions to this dilemma are to either make the internal thread pitch diameter larger, the external thread pitch diameter smaller, or to revise both the internal and external thread pitch diameters TECHNICAL ARTICLE to provide the extra room needed to accommodate the heavier finish build-up between the mating threads. Several suppliers of threaded fasteners have addressed the heavy coating-thread interference problem by making the internal threads to the thread class “6E” instead of “6H” and the external threads to the thread class “6e” instead of “6g”. The use of the combination of “6E” and “6e” class threads instead of the most common combination of “6H” with “6g” thread classes provides approximately four time the space to accommodate plating and/or coating buildup. Internal thread class “6E” provides a plating allowance whereas the more common thread class “6H” does not provide any. CONTINUED ON PAGE 132