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Originally Posted by killernoodle
You cant really measure the amount of clamping pressure you put on a tec, just clamp it good and tight and make all the torque on all the bolts the same.
You dont wanna strip copper threads, thats for sure.
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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