Metric Threads
- Format is M major diameter (mm) X pitch (mm)
- Example: M12 X 1.75 is a thread having a nominal major diameter of 12 mm and a pitch of 1.75 mm.
- The letter M is the clue to the metric designation.
- Similar classification are given for other threads
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- Static Load Rating (always stay below) – maximum stationary load before total permanent deformation of the fastener.
- Operating Load Rating (always stay below) - maximum permissible live load before total permanent deformation of the fastener.
Standards (Page link)
- ASTM's fastener standards specify, test, and evaluate the material, dimensional, mechanical, and metallurgical properties of various fasteners. These fastener standards allow manufacturers and users to examine fasteners to ensure their strength and quality for safe utilization1.