The Forgotten Factor
If you have used a torque wrench to ensure correct bolt tension, then you have just become a victim of friction – the forgotten factor. Only by controlling this factor can reliability be restored to the threaded fastener. The correct function of a nut and bolt is to clamp individual parts together with sufficient force, so as to prevent relative movement between the parts. When clamped parts move due to the influence of shock, stress, vibration or thermal forces, structural failures can occur rapidly.
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