Poka Yoke
Error Proofing
g
Poka-Yoke = Error Proofing
DEFINITION
A device which prevents a process from
• making an error or
Î prediction
• passing a defect to user Î detection
When a defect is predicted or
an error detected:
• the process is shut down or
• a control prevents going ahead or
• a warning
i
i sentt
is
Error Proofing
2
Errors are the root causes –
Defects are symptoms
input
ERROR
output
DEFECT
CAUSE
EFFECT
Broken
machine
Non-conforming part
IIncorrectt transport
t
t
equipment
Reject
Damaged
part
Broken tool
Poor raw material
3
Error Proofing
3
Two types of Poka‐Yoke
o types o o a o e
WARNING
Indicates an error situation
requiring intervention
CONTROL
Stops production
Prevents mistakes
Bip! Bip
Line 12 is
stopped!!!
Visual aids
12
120 V
1.5 A
Error Proofing
4
Drill Poka Yoke
Buzzer or light
Limit
switches
No Poka Yoke
Stop Poka Yoke
Warning Poka Yoke
Screw Poka Yoke
Screwdriver can slip
and
d scratch
t h surface
f
Screwdriver can’t slip
and
d scratch
t h surface
f
Go-Nogo Poka Yoke
Before
After
f
φ 3.0
3 0 - 0.05
+0
0.00
00
φ 3.1 - 0.05
+0
0.50
50
φ 3.0 - 0.05
+ 0.00
φ 3.0 - 0.05
+ 0.00
Make both sides the same so it
can’t be assembled incorrectlyy
φ 2.9 - 0.05
+ 0.50
φ 2.8 - 0.05
+ 0.00
Poke-Yoke
Correct
Incorrect
POKA YOKE
Correct insertion
Error Proofing
Prevents wrong
side insertion
8
Drill Guide
Error Proofing
9
Dowel Pin Checks
Error Proofing
10
Diet or regular
g
cola?
TRANSPARENT COVER
REGULAR
ORANGE
DIET COCA
COLA
ROOT BEER
SPRITE
DIET SPRITE
DIET
STAMPED
COVER
ROOT BEER
Error Proofing
11
Position detector
F il
Fragile
Keep in
upright
position
Error Proofing
12
Street Grate
Street Grate
The cover can fall
in the sewer (when
moved)
The cover cannot fall in
the sewer. But it can be
dangerous
g
for cyclists.
y
This cover
is error proof
Error Proofing
13
Document Poke-Yoke
Ten operations are covered by
a group of instruction charts
38
St 1:
Step
1 processing
i iinner di
diam.
Bound the instruction
charts so the operator can
see only the operation
being performed
40
0
Step 2: processing outer diam.
Poka Yoke:
38
Step 1: processing inner diam.
Operator accidentally uses
the dimensions for Step 2
while
hil performing
f
i St
Step 1
Error Proofing
14
Poke-Yoke
Typist Stand
The activity symbol is used when an object is
created, changed or added to. This includes the
giving or receiving of information as well as planning
or calculating.
The transportation symbol is used when something
i moved
is
d ffrom one area tto another.
th Th
The movementt
of paper
paper within
within a
a workstation
workstation is
is not
not considered
considered
of
Transportation.
The activity symbol is used when an object is
created, changed or added to. This includes the
giving or receiving of information as well as planning
or calculating.
The transportation symbol is used when something
is moved from one area to another. The movement
of paper within a workstation is not considered
Transportation.
The activity symbol is used when an object is
created, changed or added to. This includes the
giving or receiving of information as well as planning
or calculating
calculating.
The transportation symbol is used when something
is moved from one area to another. The movement
of paper within a workstation is not considered
Transportation.
Error Proofing
15
Quality
y Files Present and Ordered
Error Proofing
16
Others
•
•
•
•
•
Opening more than one filing cabinet drawer
I
Inserting
ti a CD/DVD th
the wrong way up
Putting diesel pump nozzle in an unleaded petrol tank
Over tightening a cap with a ratchet system on it
Loosing a tool that is attached by a chain to its point of
use
Poka-Yoke = Error Proofing
DEFINITION
A device which prevents a process from
• making an error or
Î prediction
• passing a defect to user Î detection
When a defect is predicted or
an error detected:
• the process is shut down or
• a control prevents going ahead or
• a warning
i
i sentt
is
Error Proofing
18