UNDERSTANDING FASTENERS
Fastener- A mechanical device that holds or joins two or more components in definite positions with respect to each other and is often described as a bolt, nut, rivet, screw, washer, or special formed part. Tensile strength- The maximum tensile-applied load a fastener can hold prior to facture (vertical stress) Shear strength- The maximum load applied to a fastener’s axis that can be withstood prior to failure (horizontal stress) Proof Load- The tension applied load that a fastener must withstand without any indication of permanent deformation or failure. Proof load is typically calculated at 90-93% of the minimum yield strength. FASTENER IDENTIFICATION Color: Grade 8 bolts tend to be yellow in color, which is zinc yellow dichromate plating. Grade 5 bolts tend to be silver in color, which is clear zinc plating. Stainless steel bolts have a dull grey finish. Head Markings: Imperial (Fractional) bolts are identified by the number of the lines on the head + 2. A grade 5 bolt will have three lines on the head. A grade 8 bolt will have six lines on the head. Metric bolts will be designated by decimalled numbers. (8.8, 10.9, 12.9) Country of Origin: Designated by manufacturer symbol on bolt head THREAD PITCH FRACTIONAL- THREADS PER INCH (TPI) USS/UNC- COARSE THREAD SAE/UNF- FINE THREAD EX. ¼-20 HAS 20TPI (USS / UNC) ¼-28 HAS 28TPI (SAE / UNF) METRIC- MEASURED GAP BETWEEN EACH THREAD IN MM EX. M10 X 1.5 HAS 1.5MM BETWEEN EACH THREAD For further details, please call on +1 310-793-7315 or email at [email protected] or visit our website: http://www.widespreadind.com/