Poka Yoke 减少失误 防差错技术

Parker Lean System Poka-Yoke

Objective

•Define Poka-Yoke

•Describe the purpose of Poka-Yoke

•Given a work scenario, describe examples of how Poka-Yoke could be employed.

•Distinguish the difference between mistake proof and fail safe

•Describe the ideal approach of Poka-Yoke.

•Describe characteristics of Poka-Yoke solutions.

•Given examples of Poka-Yoke solutions, identify what is good and what could be improved.

Poka Yoke

•POKA -inadvertent error

•YOKE -proof

•Pronounced (POH-kah YOH-kay)

In the original Toyoda Loom, Jidoka was the principle of stopping work immediately when a defect occurred. Poka Yoke was the device that made it possible.

Original Toyoda Loom -Jidoka

Sources of Defects

•Inappropriate process specifications •Excessive process variability •Material properties and variability •Machine performance and variability •Inadvertent errors

–Humans or machines

Errors Vs. Defects

•Product defects result from errors and mistakes •Errors and mistakes will always be potential issues with operations involving people •Machines can make mistakes too

We can achieve Zero defects by catching these errors and mistakes and preventing them

from becoming product defects

Errors Vs. Defects

Mistakes (errors) are inevitable

“A human is an animal that makes

mistakes”--Shingo

100

1 in 1

10-1

1 in 10

10-2

1 in 100

10-310-410-510-6

(Highest)

(Lowest)

Crew reaction during

air disaster

Simulated military

emergency

Passive inspections

(general walk -arounds )

Monitor/inspector fails to recognize initial error by operator

Simple arithmetic errors (without re -doing calculation on separate paper)

Missetting large

manual values (no

status indication except open or

closed)

Technician “seeing ”an out of calibration instrument as “in

tolerance ”

General error of omission (no control room display)

General error of omission for items

embedded in

procedure

Selection of switch dissimilar in shape

or location to

desired switch

Missetting large manual valves (controlled by procedure keys, chaining, etc.)

Selection of key operated switch rather than non -key switch (does not include error of decision)

General errors of commission (e.g., misread label and selected wrong

switch)

Upper limit to credibility Two -man team (one do; one check then reverse roles)

SOURSE: System Safety 2000, Joe Stephenson (New York: Van Nostrand Reinhold, 1991)

Human Error Rates