Page 9 - Industrial Technology February 2020

MACHINE BUILDING

Torque wrench calibration

LINEAR MOTION

LINEAR MOTION SYSTEMS AND ENERGY CHAINS PROVE KEY IN THE process to comply with ISO 6789:2017, ISO 6789:2003
or type approval requirements for manufacturers.
WORLD’S FIRST UNIVERSAL TORQUE WRENCH CALIBRATION MACHINE
The fully-automated UTWCM uses AWS Intelligent
Inline Torque Transducers (IITTs) and the AWS
hen developing a new torque wrench discovered ones that required a mammoth 110kg force. Professional Transducer Display (PTD) to provide feedback
calibration machine, Advanced Witness “We needed to beef up the machine dramatically; the to the microcontroller, automatically detecting a first peak
Systems (AWS) turned to Igus for its low original drives could not cope and there was too much signal for setting type wrenches, stopping the machine
Wfriction plain bearing, drylin linear drives friction on the bearings. To overcome these issues, we and returning to zero, greatly speeding up the calibration
and cable management systems. The design project, worked with Igus adding in a gearbox, larger linear process and reducing operator input. With indicating
which took only 18 months to complete, enables AWS to crosstrack and modifying the bearings.” wrenches, the operator stops the machine when the
offer calibration accredited laboratories and large OEMs The result is the AWS Universal Torque Wrench torque wrench displays the target torque. An optional
the most advanced and truly universal torque wrench Calibration Machine (UTWCM), which provides an transducer switch box keeps AWS IITTs powered up
calibration machine in the world. efficient and cost-effective means of calibrating and continually, allowing quick changeover between
Based in Banbury, Oxfordshire, AWS is a leading testing manually operated torque wrenches to transducers. The semi-automatic version relies on the
designer of torque transducers, instrumentation control international or company specific standards and operator to instruct the machine as to when 80% of the
systems, calibration apparatus and certification software specifications. It is designed to calibrate and test target torque has been reached, so that the machine
programs. Its pedigree traces back more than 40 years to wrenches up to 2,500Nm and equivalents. The benefit of slows to the correct rate, and to stop the machine when
managing director Ron Sangster who has been involved in using the machine is that it removes the need for the target torque is reached.
developing national and international torque standards as operators to manually apply, at the right speeds, high The built-in microcontroller controls the accuracy of
well as national standard calibration machines. While forces when calibrating large torque wrenches. Instead, the load applied and operation speeds of which there are
consulting for the National Physical Laboratory he the machine applies the force using AWS proprietary four settings for different ranges of tools. This ensures the
designed the Master 2kNm torque calibration machine, firmware, a stepper motor and linear guide system. adherence to the minimum target torque approach times,
which has been proven to be one of the most accurate complying to the ISO standard, for the capacity of wrench
torque calibration machines in the world. Minimising parasitic forces being calibrated. Multiple safety features ensure that the
“Torque wrench calibration machines are generally Available with either semi- or fully-automated operation, machine, transducers and torque wrench are not
intended for a specific manufacturers’ products,” says the UTWCM applies the force to the tool via a linear overloaded in operation or over driven due to a wrench
Sangster. “For laboratories and OEMs this can be a real carriage stepper motor and a proprietary microcontroller. fault. Since the launch of UTWCM a few months ago, the
nuisance, requiring several different machines to cover This set-up assists in minimising the parasitic forces company has sold all that it has built so far with new
each torque wrench manufacturer – which can be applied to the torque wrench handle. The machine can be orders coming in quickly. “We were given great technical
expensive and takes up a lot of bench space.” used with the latest AWS Kepler software, Kepler 4, to support from Igus throughout the design project
Sangster’s aim therefore was to develop a truly speed up completion of the calibration and certification journey,” Sangster concludes.
universal machine, able to meet the ISO6789:2017
manual torque tool standard, that would be able to
guarantee the absolute and consistent accuracy of any
torque wrench, be it a tool for use with bone screws used
in prosthetic surgery, a click torque wrench for tightening
a car’s wheel nuts or a torque wrench used for aviation,
construction and heavy machinery assembly. He also
wanted the machine to operate quietly and require as little
maintenance as possible. “Technicians appreciate using
quiet equipment in their labs; unwanted background noise
can be annoying,” he explains. “They also do not want to
have to regularly maintain their equipment – long life and
high reliability are therefore other key criteria.”
On searching the market for low maintenance and low
friction bushings and bearings, linear drive systems and
cable management systems, designers at AWS contacted
Igus. “We received a high level of technical support from
Igus, as well as many samples from the Igus iglidur
bearing, drylin E linear drives and e-chain ranges, to
realise the initial design concept for the machine,” adds
Sangster. Initially the focus was to accommodate torque
wrenches requiring forces up to 50kg applied to the
handle, but during the 18-month design project Sangster
MORE INFORMATION: www.igus.co.uk • sales@igus.co.uk • Tel: 01604 677240

February 2020 •INDUSTRIAL TECHNOLOGY 9