Table 3: Realignment of RPNs into Groups
Potential failure mode
Human errors in scaling, mixing and packing
Temperature problems in storage and freezers
Poor quality ingredient received
Worn or damaged machines
Incorrect machine settings
Metal detector malfunction
Poor loading
Poor driving
Storage with noxious items
RPN
280
165
54
42
24
18
16
16
10
over 45 in the first risk assessment, we will also be lowering
many of the other scores as well. The four failure modes that
exceed the cutoff point in the cookie process are: human error
in counting, wrong ingredients added, sloppy packing (i.e., the
placing of sheets of frozen cookies in the case haphazardly,
causing breakage) and wrong percentages of ingredients added.
The focus of the group on reduction of human error should
bring;these;areas;into;acceptable;RPN;range;by;decreasing
the occurrence or severity of the failures, or by increasing the
likelihood of detection of the failure.
Since excellence in quality comes from improvements to the
system that will reduce defects rather than detecting errors after
they have already occurred, the team should focus their efforts
on decreasing the occurrence of quality failures, or decreasing
their severity. 14
cookie process. The relative closeness of the frequencies of the
problems as charted makes the diagram less useful
than;it;could;be.;A;methodology;described;by;Ronen
et al. 12 and later expanded upon by Grosfeld-Nir et
al. 13 proposes that classifying problems by symptoms
rather than specific areas of a process will generate a
much more useful Pareto diagram in this situation.
Certain problems recur at different points in the
process and are more representative of the problems or
symptoms that need to be addressed. If we rearrange
the first risk assessment using causes of recurring
symptoms, such as temperature problems in freezing
and;storage,;and;combine;their;RPN;numbers,;we
get a chart with a much clearer definition of the “vital
few” problems and a more definitive Pareto diagram (Table 3
and Figure 3). Temperature control and human error now stand
out as the “vital few” that are causing most of the defects.
By addressing the problems highlighted by the new Pareto
diagram, we will not only be addressing the items that were
To accomplish this reduction, the cause of the failures must
be;identified.;Root-cause;analysis;will;allow;the;team;to;drill
down to the why the problem occurs, not just the what or how
it occurs, 15 usually completed via the Ishikawa, or fish bone,
diagram (Figure 4), which is a qualitative tool that determines
the root causes of the problem being examined16 and
begins as an arrow with the problem written at its
tip. Branches are drawn from this tip to outline the
primary causes for the problem. Then secondary causes
are drawn as branches from these primary causes. This
branching continues until you arrive at a root cause of
the problem. The first problem the team will analyze
will be the one that was identified as the leading cause
of quality failures in the Pareto diagram, in this case,
human error in the production process that causes
defects.
After this analysis, the root causes of the errors are
found to be the following:
•;Poor;supplies;procurement/supplier
•;Poor;management;in;production
The implementation of the FMEA tools beyond the
existing HACCP program has improved the quality
of the frozen cookies in both areas: food safety and
consumer satisfaction with appearance and taste.
