LIT-AT100 AIMCO Master Catalog rev 03-01-22 low res - Catalog - Page 77
Torque Measurement: Overview
Torque measurement and the verification of torque tools and applied torque are an integral part of today’s threaded
assembly process. The method used to measure torque can affect the judgments made regarding tool performance,
assembly processes and overall product quality.
DYNAMIC TORQUE
RESIDUAL TORQUE
Dynamic torque is the torque produced during the actual
tightening process, normally measured using rotary
transducers and a torque analyzer.
Residual torque is the torque measured by producing
an incremental amount of movement of the fastener
after the actual tightening process, normally measured
using a dial or digital torque wrench.
Advantages:
Advantages:
• Reduces operator influence
• Measures applied torque
• Easy access to fastener
• Can also include angle of rotation as error proofing
parameter
• Error proofing
• Can detect missed fasteners or joints with
significant relaxation
HARD JOINT
SOFT JOINT
Less than 30° degrees
of rotation
Metal
Metal
Metal
Metal
720° degrees or more
of rotation
Metal
Metal
Gasket
Gasket
Metal
Metal
AUDIT METHOD
AUDIT METHOD
OR
OR
Dynamic Torque: 15 Nm
Residual Torque: 18 Nm
Dynamic Torque: 15 Nm
Residual Torque: 12 Nm
Values as examples only
Values as examples only
A hard joint, one requiring a low degree of rotation during
tightening, will normally show very little relaxation after
tightening. Due to the high amount of remaining clamp
load and friction within the joint members, additional
movement of the fastener requires additional torque
energy to be applied. Therefore, Residual Torque values
will be higher than Dynamic Torque values.
A soft joint, one requiring a high degree of rotation during
tightening, will normally show significant amounts of
relaxation after tightening. Relaxation leads to a loss of
clamp load and friction within the joint members. Due
to this relaxation, additional movement of the fastener
requires relatively small amounts of additional torque
energy and Residual Torque values will be lower than
Dynamic Torque values.
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