Page 249 - The Handbook for Quality Management a Complete Guide to Operational Excellence

236 P r o c e s s C o n t r o l S u p p l y C h a i n M a n a g e m e n t 237

% On-Time
Vendor % Lots Accepted Price ($) Deliveries
A 90 60 80
B 100 70 100
C 85 50 95

Table 11.3 Example Vendor Performance Data

Quality Delivery Overall
Vendor Rating Price Rating Rating Rating
A 450 250 160 860
B 500 214 200 914
C 425 300 190 915

Table 11.4 Calculated Vendor Ratings

Generally, attempts to condense multifaceted evaluations into a single
index are subject to fundamental error. As such, it’s important to consider
them in proper context, and allow room for some level of subjective inter-
pretation. Characteristics of useful rating schemes include:

1. The scheme is clearly defined and understood by both the buyer
and the seller.
2. Only relevant information is included.
3. The plan should be easy to use and update.
4. Rating schemes should be applied only where they are needed.
5. The ratings should “make sense” when viewed in light of other
known facts.

Special Processes

A special process is one that has an effect that can’t be read ily determined
by inspection or testing subsequent to processing. The diffi culty may be
due to some physical constraint, such as the difficulty in verifying grain
size in a heat-treated metal, or the problem may simply be eco nomics,
such as the cost of 100 percent X-ray of every weld in an assembly. In these
cases, special precautions are required to ensure that processing is carried
out in accordance with requirements.
The two most common approaches to control of special processes are
certification and process audit. Certification can be applied to the skills of
key personnel, such as welder certification, or to the processes themselves.

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