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are based on management’s current beliefs and expectations. The forward-looking statements in this
release are subject to uncertainty and changes in circumstances and involve risks and uncertainties
that may affect the company’s operations, markets, products, services, prices and other factors as
discussed in the Huntsman companies’ filings with the Securities and Exchange Commission.
Significant risks and uncertainties may relate to, but are not limited to, financial, economic,
competitive, environmental, political, legal, regulatory and technological factors. Accordingly, there
can be no assurance that the company’s expectations will be realised. The company assumes no
obligation to provide revisions to any forward-looking statements should circumstances change,
except as otherwise required by securities and other applicable laws.
For press information only please contact:
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Tregartha Dinnie Ltd.
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Fax +44 1908 306 505 (number not to be published)
Email: press@tregartha-dinnie.co.uk
Sales enquiries should be directed by mail or e-mail to:
Urs Waldvogel at the Product Support Help Desk
Huntsman Advanced Materials (Switzerland) GmbH
CH 4057
Basel
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Tel : 00 41 61 96 63 87 5
Email: advanced_materials@huntsman.com or urs_waldvogel@huntsman.com
ASSOCIATIONS
Issue 49 – January 2008 – Fastener & Fixing Europe – www.fastenerfair.com
102
Component manufacturers are inevitably faced with demands
for zero defects – i.e. that every part in a batch should be “to
drawing”. This is no different for manufacturers of fasteners,
who are often using manufacturing techniques that make it very
difficult to achieve zero parts per million defective from their
normal process output.
In many manufacturing processes, the output of some of the key
parameters follows a normal distribution, and SPC techniques for
controlling quality of processed parts utilise the mathematical
relationships that accompany such a distribution. These
techniques started to be introduced by automotive and other
component manufacturers nearly fifty years ago to overcome the
often poor quality of components used in the assemblies at that
time. Figure 1 shows a familiar normal distribution curve, with
intervals of “standard deviation” or sigma marked on the curve,
which are measures of variation in the output of the process.
Figure 1 shows the proportion of parts produced that are captured
by each interval of standard deviation, and at +/- 4 sigma, about
99.993% of parts are captured.
In the early days of implementing SPC, manufacturers sought to
control their processes within +/- 4 sigma, equivalent to a process
capability, Cpk, of 1.33. Obviously, there is a relationship between
the process capability value, and the number of predicted parts per
million defective. This is shown in Table 1. For Cpk = 1.33, we can
expect 64 parts per million defective parts, and for large volume
manufacturers, of say automobiles, white goods or consumer
products, who may order components in millions, that is too many.
So now demands have moved on, and nearly every large company
has training programmes for the achievement of six sigma, shown
in Figure 2, which is done by the reduction of variation in
processes. This is equivalent of Cpk = 2.0, and gives an expectation
of less than 1 ppm, if the process is centred, but in practice most
processes shift away from being centred, so the expectation of ‘sixsigma’
specialists is for 3.4 ppm, once a Cpk of 2.0 is achieved
This is still not zero defects, but is an achievable goal in many
processes. The problem for manufacturers of fasteners is that they
are often purchased on the basis of “cost down”, and reduction of
process variation can only be achieved by investment in new
machinery or equipment.
In order to try to defend the position of the manufacturers, the
French fastener trade association (AFFIX) has published, via their
Automotive Committee, a document which shows what typical
expectation they have for ppm values in traditional processes. They
have offered this document to EIFI, for adoption by their members,
and it is shown on the EIFI website, www.eifi.org. It shows that to
achieve low levels of ppm, manufacturers must employ automatic
sorting techniques. Tables 3 and 4 show their agreed expectation
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