Screw Torque Question
Post Reply   Forum
Posted by: tom0067 ®

09/26/2006, 11:26:49

Author Profile
eMail author
Edit

Seems like such a simple thing, but I am having a difficult time locating a recommended screw torque for an M2.5x0.45 machine screw which will clamp a PCB to a diecast aluminum heatsink with threaded holes.

Anyone have a good reference to consult or recommendation?







Modified by Administrator at Thu, Sep 28, 2006, 13:09:26


Post Reply
Tell a Friend (must be logged in)
Alert Admin About Post
View All   | Next |

Replies to this message

Re: Screw Torque
Re: Screw Torque -- tom0067 Post Reply Top of thread Forum
Posted by: TZA ®

09/28/2006, 13:35:07

Author Profile
eMail author
Edit

The generic procedure for any screw is in Shigley and Mishke's Mechanical Engineering Design, although there are common lookup tables from vendors, etc.

Generically, get the proof strength of your screw (Mcmaster Carr probably has it). The recomended preload (as force, not torque) i believe is 75% of proof strength for reusable screws. Use the screw equations to translate from force to torque. The rule of thumb version, Torque =~ .20*Preload*screw diameter. Watch out for units!

Make sure you check the shear force of the thread in the heat sink too, assuming your screw is not aluminum!







Modified by TZA at Fri, Sep 29, 2006, 15:49:15


Post Reply
Tell a Friend (must be logged in)
Alert Admin About Post
Where am I? Original Top of thread
Re: Screw Torque
Re: Screw Torque -- tom0067 Post Reply Top of thread Forum
Posted by: devitg ®

09/28/2006, 10:07:51

Author Profile
eMail author
Edit

from the PROTO tools catalogue

for a class 4.8 grade, it shall be 1.05 Newton-meter
9.8 2.20
12.9 3.29







Modified by Administrator at Thu, Sep 28, 2006, 13:07:36


Post Reply
Tell a Friend (must be logged in)
Alert Admin About Post
Where am I? Original Top of thread | |

Powered by Engineers Edge

© Copyright 2000 - 2024, by Engineers Edge, LLC All rights reserved.  Disclaimer