Originally Posted by Captleemo
As far as affecting the torque is concerned I have always heard that neverseize or some type of lubricant will give a more accurite torque as your not fighting dry or rusty threads which will affect the torque reading.
Torque values are generally specified with this "potential for friction/resistance" already considered so I would suggest that what you may have always heard is not the "full story."
When lubricant is applied to fasteners and then torqued to a specific value, the conventional theory is that specified torque value should be reduced on the order of 25% due to reduced resistance. Properly connected fasteners have the male thread pulling in the opposite direction of the female thread to a point where the connection should not come loose nor should either part of the connector be stressed to the degree that it breaks. It really is about relative positioning of the two parts of the fastener to each other. The torque value specified is intended to produce the proper opposing force between the two. So "accurate" torque would be having this proper opposing force, and lubricant on the fasteners will affect when the fastener stops turning when tightened with a torque wrench or torque screwdriver, potentially altering the resulting opposing forces.
A torque wrench is not a "smart" tool. Whatever the setting, you apply force and it releases when it cannot overcome the force needed to tighten any further. The problem is, with lubed fasteners, you may apply enough force to stress (stretch) the fastener before the torque wrench releases, to the point that it shears/breaks/strips out immediately or at some future time. Again, torque values are normally specified for dry fasteners, and should be reduced when lubricants such as antisieze are employed.
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