Page 36 - EngineerIT November 2021

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The Torque laboratory at the

National Metrology Institute of

South Africa

orque remains one of the most Correct torque measurements are therefore
important measurement parameters vital for reliable and efficient manufacturing
Tin the manufacturing industry. The of products, as well as for safety, health, and
manufactured quality of many engineering fair trade.
components and techniques is heavily The Torque laboratory at the National
dependent upon the precise measurement Metrology Institute of South Africa (NMISA)
and control of torque. Examples of such plays an important role in the torque
include the following: measurement industry by developing and
• Mechanical joint clamping force maintaining the National Measurement
• Pipe fitting integrity (proper sealing) Standard (NMS) for Torque (N∙m). The
• Motor, pump, wind turbine, gearboxes, laboratory is also responsible for the
drivetrain and engine efficiency dissemination of torque traceability to
• Public safety related to childproofing South Africa and the Southern African
medicine container lids/caps Development Community (SADC) region
through the calibration of torque transducers.
Furthermore, the laboratory operates a Torque
Comparator Machine (TCM) that can generate
torque from 50 N∙m to 20 kN∙m at high
precision and accuracy (Figure 2).
It is used to calibrate torque transducers
by comparison method using high accuracy
torque transducers as references. The
reference torque transducers are shown in
Figure 3.
The reference torque transducers
are calibrated regularly at International
Metrology Institutes (NMIs) with better
Calibration Measurement Capabilities
(CMCs). This ensures that traceability to
the International System of Units (the SI)
for the torque parameter is maintained.
The TCM has CMC of 0,03 % throughout its
measurement range. In addition, the TCM
can perform calibrations of a wide range of Figure 2: The Torque Comparator Machine

Figure 1: Examples of torque quality control. Figure 3: Reference torque transducer used in the Torque Comparator Machine.

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