Recommended Torque Specifications - Macjine Screws

[seti]

Were can I find the recommended torque specifications for various machine screw fasteners? The application is sheet metal enclosures utilizing standard PEM fasteners and steel screws.

 

[Tunalover]

seti-
A. Always calculate the torque using the portion of the joint with the lowest yield point. That is, if the internal thd matl has a lower yield point than the external thd matl, do the calculations using the yield pt of the the internal thd matl.
B. Use a stress equal to 75% of the yield point. This is a widely-used rule.
C. Use a good torque-calculating program. TORKSENSE out of the UK is about $100US and is exceptionally well documented with a wide choice of materials for the both halves of the joint. It also let's you account for lubricants. To buy it, do an internet search on the name and look for the seller. It's an awesome program in my opinion. Although it's out of the UK, it is friendly with US matl specs (e.g. ASTM, ASM,...) and has both metric and english fasteners.
D. Always check the captive fastener's torque-out figure and compare it with your other results. In RARE cases, you may have to lower the torque value to accommodate the captive fastener's torque-out figure.

Tunalover