Page 355 - The Handbook for Quality Management a Complete Guide to Operational Excellence

342 C o n t i n u o u s I m p r o v e m e n t I m p r o v e / D e s i g n S t a g e 343

impossible. For example, a company was experi encing a sporadic prob­
lem (note: the words “sporadic problem” should raise a flag in your mind
that inadvertent human error is likely!) with circuit board defects. It seems
that occasionally entire orders were lost because the circuit boards were
drilled wrong. A study revealed that that problem occurred because the
circuit boards could be mounted backward on an automatic drill unless
the manufacturing procedure was followed carefully. Most of the time
there was no problem, but as people became more experienced with the
drills they sometimes got careless. The problem was solved by adding an
extra hole in an unused area of the circuit board panel, and then adding a
pin to the drill fix ture. If the board was mounted wrong, the pin wouldn’t
go through the hole. Result: no more orders lost. It would never happen
again because it could never happen again.
Another method of reducing human errors is automation. People
tend to commit more errors when working on dull, repetitive tasks, or
when working in unpleasant environments (e.g., due to heat, odors,
noise, fumes, and so on). Automation is very well suited to this type of
work. A highly complicated task for a normal machine becomes a sim­
ple repetitive task for a robot. Elimination of errors is one justification
for an investment in robots. On a more mundane level, sim pler types of
automation such as numerically controlled machining centers often pro­
duce a reduction in human errors.
Another approach to the human error problem is ergonomics, or
human factors engineering. Many errors can be prevented through the
application of engineering principles to design of products, processes,
and workplaces. By evaluating such things as seating, lighting, sound lev­
els, temperature change, workstation layout, etc., the environment can
often be improved and errors reduced. Sometimes human factors engi­
neering can be combined with automation to reduce errors. This involves
automatic inspection and the use of alarms (lights, buzzers, etc.) that warn
the employee when he’s made an error. This approach is often consider­
ably less expensive than full automation.

Technique Errors
As an example of technique errors, consider the following real­life prob­
lem with gearbox housings. The housings were gray iron castings and the
problem was cracks. The supplier was made aware of the problem and
their metallur gist and engineering staff had worked long and hard on the
problem, but to no avail. Finally, in desperation, the customer sat down
with the supplier to put together a “last­gasp” plan. If the plan failed, the
customer would be forced to try an alternative source for the casting.
As might be expected, the plan was grand. The team identified many
important variables in the product, process, and raw materials. Each
variable was classified as either a “control variable,” which would be

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