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| techtalk:ref:tools806 [2020/04/29 00:27] – [Torque Range] hippysmack | techtalk:ref:tools806 [2021/01/29 01:07] (current) – hippysmack | ||
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| - | ====== REF: HD List of Hardware P/N & Descriptions ====== | ||
| - | \\ | ||
| ====== Strengths Of Various Fasteners ====== | ====== Strengths Of Various Fasteners ====== | ||
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| ====== Grade Marks and Material Properties for Bolts and Screws ====== | ====== Grade Marks and Material Properties for Bolts and Screws ====== | ||
| - | Bolts, screws and other fasteners are marked on the head with a symbol that identifies the grade of the fastener.\\ | + | Bolts, screws and other fasteners are marked on the head with a symbol that identifies the grade of the fastener. |
| The grade specification establishes the minimum mechanical properties that the fastener must meet. \\ | The grade specification establishes the minimum mechanical properties that the fastener must meet. \\ | ||
| Additionally, | Additionally, | ||
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| {{: | {{: | ||
| - | ===== Torque Range ===== | + | |
| - | Torque specifications are normally stated within a range and not a specific number. \\ | + | |
| - | When the nut on a bolt is tightened; \\ | + | |
| - | An initial tensile load is placed on the bolt that must be taken into account in determining it's safe working strength or external load-carrying capacity. \\ | + | |
| - | The total load on the bolt theoretically varies from a maximum equal to the sum of the initial and external loads. \\ | + | |
| - | (from when the bolt is absolutely rigid and the parts held together are elastic) to a minimum equal to either the initial or external loads, whichever is the greater. \\ | + | |
| - | (where the bolt is elastic and the parts held together are absolutely rigid). \\ | + | |
| - | No material is absolutely rigid, so in practice the total load values fall somewhere between these maximum and minimum limits. \\ | + | |
| - | (depending upon the relative, elasticity of the bolt and joint members) \\ | + | |
| - | The range is given to accommodate these factors. \\ | + | |
| ====== Mechanical Properties and Grade Markings of Nuts ====== | ====== Mechanical Properties and Grade Markings of Nuts ====== | ||
| - | Three grades of hex and square nuts designated Grades 2, 5, and 8 are specified by the SAE 1995 standard covering nuts in the 1/4" to 1-1/2" diameter range. \\ | + | Three grades of hex and square nuts designated Grades 2, 5, and 8 are specified by the SAE 1995 standard covering nuts in the 1/4" to 1-1/2" diameter range. |
| Grades 2, 5, and 8 nuts roughly correspond to the SAE specified bolts of the same grade. \\ | Grades 2, 5, and 8 nuts roughly correspond to the SAE specified bolts of the same grade. \\ | ||
| Additional specifications are given for miscellaneous nuts such as hex jam nuts, hex slotted nuts, heavy hex nuts, etc. \\ | Additional specifications are given for miscellaneous nuts such as hex jam nuts, hex slotted nuts, heavy hex nuts, etc. \\ | ||
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| ====== Detecting Counterfeit Fasteners ====== | ====== Detecting Counterfeit Fasteners ====== | ||
| - | Fasteners with markings identifying them as a specific grade or property class are counterfeit if they don't meet standards established for that class. \\ | + | Fasteners with markings identifying them as a specific grade or property class are counterfeit if they don't meet standards established for that class. |
| Counterfeit fasteners may break unexpectedly at smaller loads than expected. \\ | Counterfeit fasteners may break unexpectedly at smaller loads than expected. \\ | ||
| Generally, these fasteners are made from the wrong material or they are not properly strengthened during manufacturing. \\ | Generally, these fasteners are made from the wrong material or they are not properly strengthened during manufacturing. \\ | ||
