Beyond Shingo: Prompt, Do, Check, Act (PDCA) & Universal Mistake Prevention and Quality
Verification (UMPQV)
New tools for your "Lean" toolbox
Tom Wiesen
VP Engineering & Product Development - AVOW, LLC
Copyright 2005 Page 2
Agenda
• Introduction to PDCA• Poke-Yoke & UMPQV• Relationship between PDCA & UMPQV
Copyright 2005 Page 3
What is PDCA?
• Prompt, Do, Check, Act• Based on Shewhart Model (Plan, Do,
Study, Act) for continuous improvement• Model for any manual process
Operation Post Operation
Prompt Do Check Act
Copyright 2005 Page 4
“Prompt” Explained
• What does a Prompt do?– Initiate action– Authorize– Indicate
• What actions need to be performed• How the action is to be performed• Parameters of the action• What constitutes completion of the action
Copyright 2005 Page 5
“Prompt” Explained
• A Prompt encourages humans to perform the required process steps correctly.
• PROACTIVE prompts are much more effective than passive prompts
Copyright 2005 Page 6
“Prompt” Examples
Passive Proactive• Paper Manuals• Printed Instructions• Files that musts be
opened manually• Training (Memory)
• Buzzers• Lights• Voice• Electronic
displays
Copyright 2005 Page 7
“Do” Explained
• Perform (Control) the task– Methods
• Automatic (PLC, PC, etc)– Inputs: sensors, electronic data, software– Outputs: actuators, data, alarms
• Manual (Human Brain)– Inputs: touch, see, smell, hear, taste– Outputs: muscles, speech
Copyright 2005 Page 8
“Do” Examples
• Picking parts from storage locations• Placing parts in machines• Assembling parts• Operating hand tools (hammer, drill,
screwdriver, etc.)• Mixing solutions• Medical examinations/procedures
Copyright 2005 Page 9
“Check” Explained
• Verify that the “Do” was done right– Operation completed– Quality metrics– Quantity – Functionality
• Automatic checks are much more effective than manual checks
• Check should be objective
Copyright 2005 Page 10
“Check” Explained
• Types of Checks– Judgment– Informative
• Source Inspection• Self Check• Successive Check
– “Inspection” is controversial (non-value added)
Copyright 2005 Page 11
“Check” Explained
• Inspections should strive to be:– Frequent (100%)
• Occurrences of mistakes in human controlled processes are inherently unstable, making sampling operations useless
– Inexpensive– Simple
Copyright 2005 Page 12
“Check” Examples
• Visual inspection• “Feel”• Sound• Measurement (distance, torque, etc.)• Test equipment (pressure/leak test, etc)• Functional test
Copyright 2005 Page 13
“Act” Explained
• Act - Negative Outcome– Communicate outcome to:
• Operator• Control system• Quality/Production/Enterprise system
– Resolve negative outcome• Fix/Re-work/Scrap part• Find root cause• Correct cause
Copyright 2005 Page 14
“Act” Explained
• Act - Positive Outcome– Communicate outcome to:
• Operator• Control system• Quality/Production/Enterprise system
– Identify part– Transfer part
Copyright 2005 Page 15
“Act” Examples
• Indicating light or display• Transfer part to next station• Engrave serial number• Communicate results electronically• Repair defect• Remove part from line for disposition
Copyright 2005 Page 16
Part of a Lean Strategy
• What methods makes up Lean?– 5S– Kanban– Kaizen– Mistake Prevention (Poka-Yoke)– Total Productive Maintenance– Value Stream mapping– Takt Time– Cellular Manufacturing
Copyright 2005 Page 17
Part of a Lean Strategy
• How does PDCA fit into Lean?– Prompting
• Reduces wasted production time through increased productivity
• Reduces mistakes
– Check• Reduces Re-work & Scrap• Informative Inspection promotes Kaizen
Copyright 2005 Page 18
Part of a Lean Strategy
• How does PDCA fit into Lean?– Act
• Reduces time, money, and effort through communication with other systems
– Supply chain– Production systems– Quality systems
• Visibility of the entire enterprise allows what was previously seen as waste to be seen as added value
Copyright 2005 Page 19
Applying PDCA
• Use as design criteria for design of new manual processes
• Incorporate into Process FMEA– Instead of just looking at ways the process
can fail, look for absence of PDCA steps that ensure that process is correct
• Use to evaluate/improve current manual processes
Copyright 2005 Page 20
Overview of Poke-Yoke
• Japanese for “Mistake proof”• Developed by Shigeo Shingo• Primarily focused on preventing
mistakes before they become defects• Poke Yoke devices help prevent errors
and defects• Product Focused devices• Based on 100% inspection (Informative)
Copyright 2005 Page 21
Overview of Poke-Yoke
• Generally applied to discrete systems or processes
• Best applied to high volume, low variety production
• Generally not well applied to high variety production or complex operations
Copyright 2005 Page 22
UMPQV vs. Poka-Yoke
Universal Mistake Prevention and Quality Verification
• Includes all the elements of Poke-Yoke• Universal
– Process Oriented, not product oriented– Inexpensive, Redeployable, COTS
• “Mistake-Proof” split into Mistake Prevention and Quality Verification
Copyright 2005 Page 23
UMPQV - Universal
• Process oriented, not product oriented – Configurable to multiple product
applications• Easy to Integrate
– Standard physical and electronic interfaces– Programmable (Configurable)
• Expandable & Easy to change• Communication
Copyright 2005 Page 24
UMPQV - Mistake Prevention
• Essence of Poke-Yoke– Prevent mistakes before they happen
• Source Inspection• Self Check• Subsequent Check
– Based on 100% informative inspection
Copyright 2005 Page 25
UMPQV - Quality Verification
• Verify that the outcome is “Good” not just “Not Bad”
• Mistake Prevention is a precursor• “Mistake-Proof” does not imply that
quality is verified• Informative - If quality is not verified,
find out why and correct
Copyright 2005 Page 26
UMPQV - Examples
• DC Torque Tools– Socket Tray Indicates socket and proper torque
program (Prompt, Mistake Prevention)– Operator presses trigger, Controller Controls (Do)– Transducer/Current sensor verifies torque (Check,
Quality Verification)– Controller displays & communicates result (Act)– Tool is process oriented (torquing), product
independent, and provides communication (Universal)
Copyright 2005 Page 27
UMPQV - Examples
• Sensor-based Pick-to-light– Prompt light indicates bin (Prompt, Mistake
prevention)– Worker picks parts (Do)– Sensor detects proper pick (Check, Quality
Verification)– Controller communicates result (Act)– Tool is process oriented (part picking), product
independent, and provides communication (Universal)
Copyright 2005 Page 28
UMPQV – Poke-Yoke Conversion
• UMPQV devices do not have to be COTS– Go/No-Go gage used to verify/modify several
critical dimensions– Started with a few product variations– New Poke-Yoke devices (Custom designed
reference fixtures) were created for each product variation
– Over time, more than 30 custom devices created at significant expense and are complicated to use
Copyright 2005 Page 29
UMPQV – Poke-Yoke Conversion
• Poka-Yoke Issues– No method to ensure correct gage is used– No method to ensure any gage is used– Operator dependent results (subjective) – No communication or requirement for correction of
negative results
Copyright 2005 Page 30
UMPQV – New UMPQV Solution
• Electronic Measuring Device– Custom tool developed to measure critical
dimensions– Device has highly repeatable results– Communicates results to operator and
electronically to other systems– Setup/measurement requirements selected by
product model (Barcode or RFID)– Applicable to all product variations– Can require defect resolution (tagging, electronic
acknowledge, etc.)
Copyright 2005 Page 31
Example Comparison
– Array of Physical gages – No method for selecting
proper gage– No method to ensure that
any gage was used– High level of variation in
results– No communication– No requirement for defect
resolution
– One electronic measuring device– Barcode/RFID selects proper
program (Prompt, Mistake prevention)
– High repeatability and objectivity in results (Check, Quality Verification)
– Communication to Operator and electronically (Act, Universal)
– Lower life cycle cost of device
Poke-Yoke UMPQV
Copyright 2005 Page 32
Poke-Yoke vs. UMPQV
– 100% inspection – Poke-Yoke principles– Simple, Fast, Cheap
– Product specific– Low level communication– Best applied to high
volume, low variety production
– 100% inspection – Poke-Yoke principles+– Simple, but more complex
and higher initial cost– Process specific– High level communication– Best applied to high variety,
complex production
Poke-Yoke Device UMPQV Device
Copyright 2005 Page 33
Mistake Prevention Strategy
• Design mistakes out of product/process• Analyze process using PDCA Manual Process Model• Where mistakes can occur, use Source Inspection to
prevent occurrence of mistakes that lead to defects• Use Self and Subsequent inspections to detect
defects (100%)• Use Control methods over warning methods when
feasible• Use UMPQV solutions where there are common
processes and/or high variety• Use end-of-line testing as a last resort
Copyright 2005 Page 34
Questions?
Copyright 2005 Page 35
Pick-to-Light examples
Copyright 2005 Page 36
Torque Tool Examples
Copyright 2005 Page 37
SPC Example
SPC Error Catching
0
1
2
Samples
Inspected Samples
Actual Defects
Top Related