bmta.co.uk
Conclusion
While the introduction of ISO 6789:2017 should result in improved
quality, and a more reflective calibration of hand torque tools, it has
introduced several challenges.
When we first understood the timescale to achieve accreditation in
the UK, we felt that this was adequate. However, due to the
significant changes in the procedure and the steps required we
quickly realised, even with basic estimates, this would be difficult to
achieve.
Thankfully with a talented and hardworking team, a close
relationship with the manufacturer and by submitting our extension
to scope before others, we were able to complete this project ahead
of schedule.
Unfortunately, the timescale and cost of investment required have
resulted in a significant reduction in the number of accredited
laboratories within the UK. While in the immediate future, calibration
of older hand torque tools to the ISO 6789:2003 standard may be
acceptable, once these tools are phased out and replaced with
items built to the new standard, customers may not be provided
with an appropriate calibration service from non-accredited
providers, thus increasing the risk of using non-compliant tools.
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The use of motorised or automated calibration systems is essential
for minimising the risk to operators and reducing calibration times to
provide a cost-effective service. The investment in this equipment
has dramatically improved our repeatability of measurement when
calibrating hand torque tools, and allowed us to maintain a cost-
effective service for our customers.
Differences in the interpretation and application of ISO standards
between countries should be addressed. The ethos behind
international standards is that items are manufactured and
calibrated to the same requirements worldwide. If assessment
bodies permit variance between countries it can increase the risk to
the end-users of the tool or users of products manufactured using
that equipment. Timescales of deployment and the view on
continued use of withdrawn standards must also be aligned and
possibly form part of the content of each standard.
References
1. EN ISO 6789-1:2017, Assembly tools for screws and nuts - Hand
torque tools - Part 1: Requirements and methods for design
conformance testing and quality conformance testing: minimum
requirements for declaration of conformance
2. EN ISO 6789-2:2017, Requirements for calibration and
determination of measurement uncertainty
3. BS 7882:2017, Method for calibration and classification of torque
measuring devices