Page 60 - Six Sigma for electronics design and manufacturing

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The Nature of Six Sigma and Its Connectivity to Other Quality Tools
RPN = SEC × OCC × DET
(1.5)
All items with an RPN that exceeds 120 should be investigated
first. An item that could cause a safety-related failure, a field recall,
or one with a high customer requirement should be considered critical
and dealt with promptly.
1.11.2.3 FMEA results. FMEA is an excellent tool for investigating po-
tential failures in products or processes. It could lead directly to im-
proving the design or manufacturing quality, especially when priori-
tizing which parts or processes to work on first. Ideally, it should be
used for all parts of the process, product, or system. In practice, a
methodology such as QFD should be established to prioritize which el-
ements are to be analyzed using FMEA.
FMEA is a good example of using tools to identify and prioritize
quality problems in design and manufacturing. It is another tool to
guide the enterprise on where to start quality improvements on the
road to six sigma. Some of the benefits of FMEA projects are:
Establish priorities as to which of the failure items should be im-
proved first
Identify potential failure modes for each item
List the types, risks, and causes of failures, and the effects these
failures might have
Calculate a risk priority number, and then use the same number to
benchmark improvement in design or manufacturing
Encourage the planning of a proposed corrective action
Establish an ordered list of current controls
List completed quality actions and who performed them
Document improvements to the process or design
1.12 Gauge Repeatability and
Reproducibility (GR&R)
The use of six sigma to communicate quality issues between the com-
pany and its supply chain is increasing, especially in cases where in-
dustries have adopted these techniques as standards for operations,
such as the auto industry. Given that the six sigma or Cpk require-
ments are spelled out in contractual agreements, it is imperative that
there be mutual agreement on the measurements of the specifications
or manufacturing variability, the two major constituents of six sigma.
Differences in measurements due to operator or equipment variability
must be accounted for within the six sigma calculations. Gauge re-