POKA YOKE

                                           POKA YOKE

 ERROR IS HUMAN NATURE BUT INTELLIGENCE IS ALSO HUMAN NATURE SO NEVER STOP ,FINDING WAYS OF NOT MAKING MISTAKES
POKA YOKE (Mistake Proofing)
WHAT IS MISTAKE PROOFING
A SYSTEM For Organismic Work that
Excludes any risk of error even by the beginner
Allows everyone to operate without mistake
Prevents error that are about to occur

INFORMATIVE INSPECTION
    ACTIVITY : USE OF S.Q.C.
    CHECK AND DISCOVER DEFECTS
       PROVIDE FEEDBACK
    ACTING ON THE BASIS OF THE
     FEEDBACK

  RESULT :Time delay, defective Parts in line
JUDGEMENT INSPECTION
ACTIVITY :
CHECK FINISHED PRODUCT
ELIMINATE DEFECTIVE ONES
   RESULT : COST INCREASES
ZERO QUALITY CONTROL
SOURCE INSPECTION
USE OF CONTROL MECHANISM
PREVENT ERROR TURNING INTO A DEFECT
Applications of  POKA-YOKE
TOOL DESIGN
MANUFACTURING PROCESS
OPERATORS (ADHERANCE TO S.O.P.)
DETECTION DEVICES




METHODOLOGY
Speak to the Job / Machine



EXAMPLE ...1
Problem: Job loading  in reverse  direction causing  job rejection , damage  to  tool  & m/c  geometry.

Aim : to ensure  correct loading of job .
IDEAS AFTER BRAINSTORMING
1) Use of proximity sensor to detect reverse loading of job.
2) Use of photo-sensor.
3) Instructions for operators
4) Separate  fixture to keep the incoming job ,to enable the operator to load the job correctly.
    5) Painting  the correct & wrong end of the job with different colours. 6) Use of colour sensors to differentiate between correct & wrong end of the job. 7) To provide work-rest for the job. 8) To provide the mechanical stopper. 9) To increase the diameter of the job at the wrong end, so that the job will not get held between the jaws before operation.
    5) Painting  the correct & wrong end of the job with different colours. 6) Use of colour sensors to differentiate between correct & wrong end of the job. 7) To provide work-rest for the job. 8) To provide the mechanical stopper. 9) To increase the diameter of the job at the wrong end, so that the job will not get held between the jaws before operation.
BENEFITS.
 M/C ACCIDENT AVOIDED.
EXAMPLE …2
 PROBLEM: T/M CASE NOT CLAMPED ON PUMP JIG , RESULTING IN REJECTION.

AIM: TO ENSURE START OF THE DRILLING  OPERATION ONLY WHEN T/M CASE IS FULLY CLAMPED BY PUMP JIG.
IDEAS AFTER BRAINSTORMING
1) Separate hydraulic clamping unit.
2) Rack & pinion arrangement for operating the jig plate.
3) Proximity sensor to detect the shift  of  t/m  case before operation.
4) Sensing the clamping operation with limit switch & audio/visual indication for the operator.
IDEAS AFTER BRAINSTORMING
    5) Inhibiting the drilling operation unless fully clamped signal is provided by limit switch. 6) Job clamping sensing  by air  pressure  & pressure switch. 7) Use of through beam fiber optic sensor to detect the gap between job & the fixture.
IDEAS AFTER BRAINSTORMING
    5) Inhibiting the drilling operation unless fully clamped signal is provided by limit switch. 6) Job clamping sensing  by air  pressure  & pressure switch. 7) Use of through beam fiber optic sensor to detect the gap between job & the fixture.
BENEFITS.
Poka-Yoke: with this habit you will never forget to take your cellphone

NO REJECTION OF T/M CASE.
EXAMPLE …3
Problem: skew drilling of main oil gallery , resulting in rejection  & field failure.

Aim: to ensure position of rotary table after indexing.
IDEAS AFTER BRAINSTORMING
    1) Use of servo motor to turn & correctly position the rotary table.
    2) Provide mechanical stopper.
    3) Use of proximity sensor to detect the correct table position & its interlock with spindle start command.
    4) Paint mark on the locator to know the correct position of the table. 5) Audio  indication  for the operator  at  the  end  of  one drilling  cycle  to  check  the proper  positioning  of  rotary table.
IDEAS AFTER BRAINSTORMING
    1) Use of servo motor to turn & correctly position the rotary table.
    2) Provide mechanical stopper.
    3) Use of proximity sensor to detect the correct table position & its interlock with spindle start command.
    4) Paint mark on the locator to know the correct position of the table. 5) Audio  indication  for the operator  at  the  end  of  one drilling  cycle  to  check  the proper  positioning  of  rotary table.

BENEFITS.

NO  REJECTION OF CRANK CASE DUE TO SKEW DRILING OF MAIN OIL GALLARY HOLE.
EXAMPLE …4
PROBLEM: T/F CASE GETTING REJECTED BECAUSE OF MANUAL OVERTRAVLE OF SADDLE IN VERTICAL DIRECTION DURING FINISH CUT ON FN3 MLLING M/C.
AIM: TO STOP MILLING OPERATION AS SOON AS SADDLE IS OVERTRAVELS.
IDEAS AFTER BRAINSTORMING.
    1) Marking on setting dial for vertical saddle stroke.
    2) Use of limit switch to sense the over travels position & stop the m/c  control.
    3) Use of mechanical stopper on the slide.
    4) Replace  manual operation with automatic cycle . 5) Restrict the movement of setting dial  at  the  point of finish cut.
IDEAS AFTER BRAINSTORMING
    1) Marking on setting dial for vertical saddle stroke.
    2) Use of limit switch to sense the over travels position & stop the m/c  control.
    3) Use of mechanical stopper on the slide.
    4) Replace  manual operation with automatic cycle . 5) Restrict the movement of setting dial  at  the  point of finish cut.
BENEFITS.


 NO REJECTION OF T/F CASE .
ADDITIONAL POKA-YOKE
Work seat failure.
Depth control in tapping of blind holes.
Inhibiting  the cycle start after job is clamped between centers.
To avoid the re-cutting of same gear on the m/c.
ADDITIONAL POKA-YOKE
To ensure proper resting of job on jig plate of multidrill m/c.
To avoid missing of drilling operation on H.M.T radial drill.
To detect incomplete drilling operation on H.M.T drill m/c