Quality Assurance

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Poka-Yoke

Overview

The term poka-yoke was applied by Shigeo Shingo in the 1960s to indus-

trial processes designed to prevent human errors (Robertson 1997). Shingo

redesigned a process in which factory workers would often forget to insert

the required spring under one of the switch buttons while assembling a

small switch. In the redesigned process, the worker would perform the task

in two steps—rst preparing the two required springs and placing them

in a placeholder, then inserting the springs from the placeholder into the

switch. When a spring remained in the placeholder, the workers knew that

they had forgotten to insert it and could correct ...