Bolt/hex Nut Strength Markings 6l74d

BOLT/HEX NUT STRENGTH MARKINGS

HEX NUT 3D VIEW

Use the strength markings to determine standard to metric. Many standard nuts have dots (on nuts), or those "lines" stamped into the bolt heads, while metric nuts & bolts are marked with a number. The greater the number, of dots, "lines" or higher the number, the greater strength of the nut. What you may not know, is the reason for specific torque values. Making a nut/bolt too tight will weaken it's strength, which can cause it to break, while too loose will cause it to eventually fall out. Grades 0-5 are usually used on Autos. All bolts, whether standard or metric, are sized according to diameter, thread pitch, and length. A standard 1/2 - 13 x 1 bolt is 1/2" in diameter, has 13 threads per inch, and is 1 inch long. An M12 - 1.75 x 25 bolt (metric) is 12mm in diameter, has a thread pitch of 1.75mm (the distance between each thread), and is 25mm long. Though the two bolts seem identical, and are easilly confused, they are not interchangeable. It should be noted that many fasterners, especially Grade 0-2 have no distiguishable markings on them. You would have to measure the diameter of the head, thread pitch, and length, or compare it to a fasterner of the same size.

PROPERTY CLASS A designation system which defines the strength of a bolt or nut. For metric fasteners, property classes are designated by numbers where increasing numbers generally represent increasing tensile strengths. The designation symbol for bolts consists of two parts: 1. The first numeral of a two digit symbol or the first two numerals of a three digit symbol approximates 1/100 of the minimum tensile strength in MPa. 2. The last numeral approximates 1/10 of the ratio expressed as a percentage between minimum yield stress and minimum tensile stress. Hence a fastener with a property class of 8.8 has a minimum tensile strength of 800 MPa and a yield stress of 0.8x800=640 MPa. The designation system for metric nuts is a single or double digit symbol. The numerals approximate 1/100 of the minimum tensile strength in MPa. For example a nut of property class 8 has a minimum tensile strength of 800 MPa. A bolt or screw of a particular property class should be assembled with the equivalent or higher property class of nut to ensure that thread stripping does not occur.