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12 Cards in this Set
- Front
- Back
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Why are threads used? |
Allow parts to be disassembled |
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State the two types of threads, and the difference between them. |
Course (common) pitch = 1.75mm Fine (specialised) pitch = 1.25mm |
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What is the pitch of a thread? |
The distance between two peaks of a thread. |
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What is the default fit size? |
6H/6g |
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Describe the features of a bolt and why it might be used |
Hex head; External thread; Plain shank near head; Fastened with washer and nut; Withstands axial force |
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Describe the features of a stud |
Thread on both sides with plane shank in the middle. One end (usually shorter) is permanent side, whilst other is removable. |
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How could you find the tensile strength of a thread? |
The number on the top of the bolt e.g. 5.x would show 500MPa |
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How could you find the yield strength of a thread? |
5.6 would show 60% of tensile strength (in this case 60% of 500MPa = 300MPa) |
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Why would you pre-tension a bolt? |
To limit the fatigue failure of the bolt |
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What limits the amount of pre-tensioning of a bolt? |
The proof stress of the bolt |
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Why might you use a lead screw? |
To provide linear movement for heavy loads |
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Why is a torque applied to a power screw jack? |
To overcome friction in the thread and raise the load in the collar |
