
98 • Root Cause Analysis
EXAMPLE 12.4
Approximately 2% of the parts produced by a process are out of specication
on length. e same process is used on ve machines across three shis, and
the unnished part comes from two suppliers. Two dierent types of cutting
tools could be used to produce the part.
A quality manager uses other quality tools to better understand the
situation, and this investigation determines that the failure happens on all
shis and with all tool types, but only occurs on two of the ve possible
machines and only involves unnished parts from one supplier.
ese items need to be understood to nd the root cause. e suppl