• Some users have recently had their accounts hijacked. It seems that the now defunct EVGA forums might have compromised your password there and seems many are using the same PW here. We would suggest you UPDATE YOUR PASSWORD and TURN ON 2FA for your account here to further secure it. None of the compromised accounts had 2FA turned on.
    Once you have enabled 2FA, your account will be updated soon to show a badge, letting other members know that you use 2FA to protect your account. This should be beneficial for everyone that uses FSFT.

TEC Module Compression Force

D

DNA

Weaksauce
Joined
Aug 7, 2004
Messages
109
The recommended compression for a TEC assembly is 150 to 300 pounds per square inch of module surface area. Using the following formula, you can calculate the torque setting per screw:

T = (C x D x F x in^2) / (# of screws)

T = torque per screw (in-lbs)
C = torque coefficient; generalized values for copper/mild steel (0.36 dry, 0.18 lubricated)
D = nominal screw size (8 = 0.164, 10 = 0.190, 1/4 = 0.250)
F = Force (lbs / in^2)
in^2 = module surface area (length x width)

Check the torque setting after one hour and retighten if necessary.

Example: Assuming (4) # 8 screws are used to secure a coldplate used with a 62mm (2.44 in) square module surface area and a surface force of 300 lbs per in^2 is required, what is the torque setting required per screw?

T = (0.36 x 0.164 x 300 x 5.95) / 4 = 26.35 in-lbs per screw



If a torque wrench/screwdriver is not available, a properly-ranged pull spring scale attached to the end of an L-shaped hex wrench can be used to establish the screw torque setting. To calculate the required spring scale pull force, apply this formula:

F = T / D

F = Force (lbs)
T = Torque (in-lbs)
D = Distance (in)

Example: What is the spring scale pull force required at the end of a 3.75 inch long L-shaped hex wrench to produce a 26.35 in-lbs screw torque setting?

F = 26.35 in-lbs / 3.75 in = 7.02 lbs pull force
 
Question - what purpose does the "D" factor play in the equation? I'm guessing it converts torque to linear force by the diameter of the fastener... but shouldn't it be the radius? Also, force is measured in lbs, whereas lbs/in^2 is a unit of pressure - to avoid confusion you shouldn't mix the two terms :D
 
Ctrl_Alt_Delete said:
so F actually = P ?
:D
Click to expand...

Yes, in the first equation, pressure is the correct term to use.
In the second one (spring scale pull force calc.), F is correct.
 
diameter is fine, that formula will get you close, but you would get just as close picking something that feels good and just torquing the screws all the same.
 
Wouldn't type of thread used also enter into the formula . Say course thread vs.fine thread . As a fine thread screw @ 12ftpounds has a much greater clamping force as compared to a course thread screw. Or did you cover that and I missed it in your formula
 
$BangforThe$ said:
Wouldn't type of thread used also enter into the formula . Say course thread vs.fine thread . As a fine thread screw @ 12ftpounds has a much greater clamping force as compared to a course thread screw. Or did you cover that and I missed it in your formula
Click to expand...

The torque coefficient C kind of covers thread variations... But coarse vs fine (threads per inch) shouldn't make a whole lot of difference, either way you're applying the same torque. You may be thinking of ultimate strength of the fastener using coarse vs fine threads. If you're reaching those levels of stress and stripping threads, you've probably got other problems (pulverized core, cracked motherboard...)
 
zer0signal667 said:
The torque coefficient C kind of covers thread variations... But coarse vs fine (threads per inch) shouldn't make a whole lot of difference, either way you're applying the same torque. You may be thinking of ultimate strength of the fastener using coarse vs fine threads. If you're reaching those levels of stress and stripping threads, you've probably got other problems (pulverized core, cracked motherboard...)
Click to expand...
i agree that you'd have problems by that point, but the pelt is clamped between the block and the cold plate, independant of the clamping force between the cooler and the CPU.
 
DFI Daishi said:
i agree that you'd have problems by that point, but the pelt is clamped between the block and the cold plate, independant of the clamping force between the cooler and the CPU.
Click to expand...


Oops, I was picturing myself tightening my waterblock mounts, which go through the motherboard. Same idea, different set of components. :D
 
You must log in or register to reply here.
Back
Top