Text preview for : Defining Your Calibration Requirement - White Paper 5991-1319EN c20140529 [5].pdf part of Agilent Defining Your Calibration Requirement - White Paper 5991-1319EN c20140529 [5] Agilent Defining Your Calibration Requirement - White Paper 5991-1319EN c20140529 [5].pdf
Back to : Defining Your Calibration | Home
Keysight Technologies
Defining Your Calibration Requirement
White Paper
Introduction
Okay, so you've convinced the accountant that the consequence of
not having your test gear calibrated is too risky and also believe you've
selected a calibration vendor that meets your organization's initial
requirements.
But what steps can be taken when actually placing the order to ensure
you get a "proper" calibration? Here's a suggestion.
How to Take the Uncertainty Out of
Buying a Service
Author: Mike Hutchins
Keysight Technologies, Inc.
The level of knowledge possessed by purchasers of calibration services varies
significantly from company to company. Some organizations employ an experienced
metrologist to make calibration purchases while others entrust this complex decision
to a non-technical purchasing function. The result of this is that the validity of
purchasing decisions varies from exceptionally good to extremely inappropriate.
Extremely inappropriate decisions invariably cost the company more money; either
because they are buying unnecessary or unnecessarily detailed calibration or, more
commonly, because they are buying insufficient or insufficiently detailed calibration.
While the insufficient option may be cheaper, it often results in far greater eventual
cost to the company through rework and incorrect decisions relating to product quality
and customer satisfaction.
To justify unnecessary calibration, a detailed knowledge of the precise application
of the equipment is required as part of the analysis but adoption of simple measures
can enable a purchaser to overcome a tendency to buy inadequate calibration. This is
particularly necessary for final test instruments and those responsible for end-product
quality. Inputs from some of the most knowledgeable technical buyers in the UK have
been used to construct the following purchase order statement which should help the
less well-informed calibration purchaser avoid the inadequacy trap:
Calibration shall be undertaken against full manufacturers' specifications. Where
equipment is found to be out of specification, full performance test results, in the as-
received condition, must be obtained before any adjustment or repair action is taken.
On completion of the calibration work a certificate of calibration is required, signed by
your authorized representative, containing a statement confirming that the calibration
can be demonstrated to be traceable to National or International standards and stat-
ing the item's full compliance with its performance specifications. Full performance
test results, taking the form of measured values, are to be supplied. Any omissions
from the full calibration are to be notified to us and shall be agreed in writing before a
certificate, clearly annotated "Limited Calibration" is issued. A declaration of measure-
ment uncertainty values shall be included with all test results.
But What Does it Mean?
This may seem a lengthy statement but it encompasses many of the important
points missed by orders which simply require "Calibration". It is because there
is no standard for what is provided under "a calibration" that such an explicit
purchase statement is necessary. A breakdown of each element of the state-
ment follows with explanation:
"Calibration shall be undertaken against full manufacturers' specifications."