bmta.co.uk
CHALLENGES OF ACHIEVING
ACCREDITATION TO ISO 6789-2:2017
Calibration of Hand Torque Tools
By Matthew Gypps
UK Technical Manager
Trescal
Hand torque tool technology and the associated calibration
requirements have progressed significantly since the standard
was last published in 2003 and a revision was required
resulting in it being divided into two parts:
ISO 6789-1:2017: “Part 1: Requirements and methods for
design conformance testing and quality conformance
testing: minimum requirements for declaration of
conformance” [1]: the method described within is very
similar to the previous standard, but the requirement for
'certificate of calibration' has been removed and replaced
with a requirement for a 'declaration of conformance' to ISO
6789-1:2017.
ISO 6789-2:2017: “Part 2: Requirements for calibration and
determination of measurement uncertainty” [2]: a significant
increase in the number of tool operations. Measurements of
the effects of the use of interface adaptors and rotation of
the output drive of the tool are all specified and required
along with the need to characterise each tool type and
record the findings.
Torque bench: Manual Loader
Through the use of automation, Trescal has reduced
these risks, improved accuracy and productivity to
enable them to cope with higher demand for this
service.
Through discussion with colleagues in other European
countries, it was evident that not only were there
differences in the interpretation and application of the
standard, but there appeared to be inconsistent
deadlines and both errors and omissions during the
translation of the standard which are still apparent
today.
This has increased the complexity of uncertainty calculation
and the result recording application. Without innovation, the
new standard significantly increases the time and effort
required by an engineer.
As the market leader for calibration with a high demand for
accredited calibration, Trescal UK aimed to be the first non-
manufacturer to obtain accreditation to the revised standard
within the UK. This meant a large amount of work was
required to determine a suitable solution, build the evidence,
submit the extension to scope and obtain accreditation in a
short time scale.
Trescal UK achieved its target one year ahead of the deadline
(March 2018). Performing more than twice the number of
operations during each calibration was going to increase work
time and the manual handling/repetitive strain injury on the
staff.
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