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PPT in support of two-day workshop on "Error-Proofing" (Poka Yoke) of industrial work processes
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ERROR PROOFINGERROR PROOFING
Quest
1/19/99 © Johnson Controls, Inc. errorprf.ppt2
Objectives:Objectives:By the end of this Workshop, be able By the end of this Workshop, be able
to….to….
• Identify 3 approaches to inspection….• Identify specific conditions that provoke errors
(Red Flags)….• Use Source Inspection to prevent defects….• Name error-proofing devices and applications….• Implement Error-Proofing in your workplace….
1/19/99 © Johnson Controls, Inc. errorprf.ppt3
LogisticsLogistics
• Start/End Times• Participation• Lunch Area/Timing• Meeting Location(s)• Restroom(s)• Telephones, Messages,
Pages• Call in Number• Refreshments• Timekeeper
1/19/99 © Johnson Controls, Inc. errorprf.ppt4
3 Basic Principles3 Basic Principles
• Error Proofing is AchievableZero Tolerance For Waste
• Stable Production Environment (eliminate Operator/machine possible
error)
• Customer “Pull” Drives Production
1/19/99 © Johnson Controls, Inc. errorprf.ppt5
Continue to be defined by customers
Will be less of a competitive advantage
Will be ‘taken for granted’ (expected)
Will require routine use of Quality tools
Will require more creativity
What will Quality be in the 21What will Quality be in the 21stst Century?Century?
1/19/99 © Johnson Controls, Inc. errorprf.ppt6
Error Proofing MeansError Proofing Means“Zero Tolerance for Waste”“Zero Tolerance for Waste”
• Fundamental belief that all errors, and the defects they cause, can be prevented = zero waste!
• Waste of correction/rework is reduced
(You MUST believe this for Poke Yoke to work)
1/19/99 © Johnson Controls, Inc. errorprf.ppt7
EVIDENCES
AT&T Power Systems reduced outgoing defects by 70% (Won Deming Prize)
TRW reduced customer PPM’s from 288 to 2
Washing machine drain pipe assembly line produced 180,000 units, in 6 months, with 0 defects.
Your experiences?
Source: Productivity, Inc.
1/19/99 © Johnson Controls, Inc. errorprf.ppt8
Error Proofing Means Error Proofing Means “Stable Production “Stable Production
Environment”Environment”
• An error-proofed process is repeatable..
• An error-proofed process is predictable
• An error-proofed process is stable.• An error-proofed process produces
higher quality product.
Repeatable
Predictable
Stable
Leads to Higher Quality
1/19/99 © Johnson Controls, Inc. errorprf.ppt9
Error Proofing Supports Error Proofing Supports ““Customer Pull’Customer Pull’
• An error-proofed process “gets it right the first time” more often.
• Improved flexibility to respond to customer demands.
• Improved quality reduces the wastes associated with “inspecting quality into the product.”
• Inspection done @ source
1/19/99 © Johnson Controls, Inc. errorprf.ppt10
Error Proofing OpportunitiesError Proofing Opportunities
1/19/99 © Johnson Controls, Inc. errorprf.ppt11
Error Proofing (Poka-Yoke)Error Proofing (Poka-Yoke)
• Improves product quality and ensures consistent process results.
• Emphasizes designing the manufacturing process to ensure zero defects.
• Requires disciplined problem-solving and beliefs that defects are not inevitable in production shops.
• Is effective when done in teams.
1/19/99 © Johnson Controls, Inc. errorprf.ppt12
• Name some products, services where you are used to receiving high quality every time....
• Any bad product or service experiences?
• Are high quality products achievable every time?
1/19/99 © Johnson Controls, Inc. errorprf.ppt13
How Can We Ensure QualityHow Can We Ensure Qualityin the Following Areasin the Following Areas??
ManMaterialMachineMethod
Information(4M + I)
1/19/99 © Johnson Controls, Inc. errorprf.ppt14
5 Elements of Production5 Elements of Production
1. MeControl: Discipline, Fundamental Education, Cross-Training Assignments
2. MaterialControl: Source Controls
5. InformationControl: Visual Controls (Instruction Sheets, Kanban)
4. MethodControl: Assembly Line & Work Standards
3. MachineControl: Conditions Assured Through Poka-Yoke & Everyone's Participation
1/19/99 © Johnson Controls, Inc. errorprf.ppt15
Inspection TechniquesInspection Techniques
Judgement (inspection) Informative (inspection) Source (inspection)
Remember Shaving?
1/19/99 © Johnson Controls, Inc. errorprf.ppt16
Judgment InspectionJudgment Inspection
“Then and
There”
1/19/99 © Johnson Controls, Inc. errorprf.ppt17
Informative InspectionInformative Inspection
• Feedback provided to upstream processes when defects are discovered.
• Uses statistics and sampling.• Seeks to minimize defects.
1/19/99 © Johnson Controls, Inc. errorprf.ppt18
Informative InspectionInformative Inspection
1/19/99 © Johnson Controls, Inc. errorprf.ppt19
Source InspectionSource Inspection
• Operations examined for conditions that may breed defects.
• Emphasis on data collection and problem solving.
• 100% inspection built into each operation.
1/19/99 © Johnson Controls, Inc. errorprf.ppt20
Self-Checking for ErrorsSelf-Checking for Errors
• Work verified before it leaves station• Build sensory + visual aids into operation• Represents 100% source inspection• Workers responsible to implement
quality control• Standards must be followed for success
(Builds out Operator Error)
1/19/99 © Johnson Controls, Inc. errorprf.ppt21
Self-Checking for ErrorsSelf-Checking for Errors
1/19/99 © Johnson Controls, Inc. errorprf.ppt22
Successive Checking for ErrorsSuccessive Checking for Errors
• Users of upstream work verify part or process for correctness before use
• Prevents cumulative errors• Builds teamwork between operations.
1/19/99 © Johnson Controls, Inc. errorprf.ppt23
Successive Checking for ErrorsSuccessive Checking for Errors
1/19/99 © Johnson Controls, Inc. errorprf.ppt24
Defects vs. ErrorsDefects vs. Errors
• Analyzing the production process to achieve zero defects = Distinguishing between defects and errors
• Defects = results (effects of mistakes )
• Errors = sources (causes of mistakes)
1/19/99 © Johnson Controls, Inc. errorprf.ppt25
Error Defect
Not tightening lug-nuts Loose metal
Setting too dark on toaster Burnt toast
Failing to clean metal Dirt in paint
Some Common Some Common Manufacturing ErrorsManufacturing Errors
Quest
1/19/99 © Johnson Controls, Inc. errorprf.ppt27
Most CommonMost CommonManufacturing ErrorsManufacturing Errors
• Omitted processing• Processing errors• Workpiece setup• Missing parts• Wrong parts• Processing wrong workpieces• Misoperation• Adjustment errors• Improper equipment set-up • Tools & jigs improperly
prepared
Why Do People Why Do People Make Mistakes?Make Mistakes?
Quest
1/19/99 © Johnson Controls, Inc. errorprf.ppt29
Most Common Human ErrorsMost Common Human Errors• Forgetfulness - Lack of task priorities• Misunderstanding - Lack of familiarity with
process• Identification - Misreading visual cues• Poor training - Lack of experience,
reinforcement• Intentional - Deliberate mistake• Willful - Ignoring rules without
harmful intent• Inadvertent - Unaware of mistake• Slowness - Delays in judgement or
physical ability• Poor Supervision - Unclear, contradictory
instructions• Surprise - Errors due to abnormal
events
1/19/99 © Johnson Controls, Inc. errorprf.ppt30
Manufacturing & Human ErrorsManufacturing & Human Errors
• Common human errors can be eliminated through process design
• Defects are not inevitable• You can achieve Zero Defects!
1/19/99 © Johnson Controls, Inc. errorprf.ppt31
1/19/99 © Johnson Controls, Inc. errorprf.ppt32
Red FlagsRed Flags(When These Things Happen…)(When These Things Happen…)
* Adjustments* Tooling/tooling change* Dimensionality/specification/critical condition* Many parts/mixed parts* Multiple steps* Infrequent production* Lack of or ineffective standards* Symmetry* Asymmetry* Rapid repetition* High volume/extreme high volume* Environmental conditions
1/19/99 © Johnson Controls, Inc. errorprf.ppt33
AdjustmentsAdjustments
Having to bring parts, tools or fixtures into a
correct relative position only by
sight or feel.
reference pin divergence
correct incorrect
1/19/99 © Johnson Controls, Inc. errorprf.ppt34
Tooling/Tooling ChangeTooling/Tooling ChangeDefects From Malfunctions or Incorrect Defects From Malfunctions or Incorrect
ToolingTooling
glue
holder
laminated surface
Spots
1/19/99 © Johnson Controls, Inc. errorprf.ppt35
Dimensionality/Specification/Dimensionality/Specification/Critical ConditionCritical Condition
Relying solely on Operator
skill for proper job setup or
precision work
1/19/99 © Johnson Controls, Inc. errorprf.ppt36
Many Parts/Mixed PartsMany Parts/Mixed Parts
Operations without safeguards to prevent use of
incorrect parts
1/19/99 © Johnson Controls, Inc. errorprf.ppt37
Multiple StepsMultiple Steps
Work requiring many small
operations or sub-tasks
1/19/99 © Johnson Controls, Inc. errorprf.ppt38
Infrequent ProductionInfrequent Production
Intermittent operations, or
production
1/19/99 © Johnson Controls, Inc. errorprf.ppt39
SymmetrySymmetry
Model X
Condition that allows parts to be installed upside
down or in mirror image
position
1/19/99 © Johnson Controls, Inc. errorprf.ppt40
AsymmetryAsymmetry
Where opposite sides of a part, tool or
fixture look identical but can only be used correctly one way.
pointer boss
washerpointer
bottom die has a flat surface
1/19/99 © Johnson Controls, Inc. errorprf.ppt41
Rapid RepetitionRapid Repetition
From Automatic Welding Machine
Next Process
Shaft Omitted
Repeating the same work over and over so that errors are not readily
detected
1/19/99 © Johnson Controls, Inc. errorprf.ppt42
High VolumeHigh Volume
Operations where output is large & fast so that errors escape visual
inspection
right side up upside down
workpiece
1/19/99 © Johnson Controls, Inc. errorprf.ppt43
EnvironmentEnvironment
wire stock
reel stand
dimensional variation
tension device
to machine
foreign matter
Physical conditions around the workplace that can adversely impact quality
1/19/99 © Johnson Controls, Inc. errorprf.ppt44
Red Flag Conditions
Operation
S S
CommentsAdjustments
Tooling Concer
ns
Critical S
pec Condition
Mixed Parts
Multiple S
teps
Infrequen
t Producti
on
Lack of S
OP
Symmetry
Asymmetry
Rapid Repitition
High Volume
Environmen
tal Conditio
ns
1/19/99 © Johnson Controls, Inc. errorprf.ppt45
Quality Data ReviewQuality Data Review
• Review top 3 quality issues (in dollars or PPM) in our area for the previous month.
• Review top 3 quality issues (dollars or PPM) in our area for the previous 3 months.
• Determine which errors reoccur.
1/19/99 © Johnson Controls, Inc. errorprf.ppt46
Production Shop ExerciseProduction Shop Exercise(60 min.)(60 min.)
• Form teams.• Decide on line/area to review.• Review operation(s) to Red Flag, using standard
form.• Consolidate ideas into groups.• Present for discussion.
1/19/99 © Johnson Controls, Inc. errorprf.ppt47
Team DebriefTeam Debrief
• Describe Red Flag Conditions Found in Your Area.
• How Do These Conditions Affect Quality?
1/19/99 © Johnson Controls, Inc. errorprf.ppt48
Implementation of Error-Implementation of Error-ProofingProofing
• Identify product defect & collect data• Track defect at:
– Point Discovered– Point Created
• Review SOP at defect creation point• Identify any deviations from SOP• Identify Red Flag condition at creation point• Implement error-proofing device to prevent
error or defect• Check results & make process adjustments
1/19/99 © Johnson Controls, Inc. errorprf.ppt49
Describe Product Defect & Collect Describe Product Defect & Collect DataData
Problem: Missing Nut Bracket Screws
1 2 3 4 5 6 7 80
5
10
15
20
25
Hour
Defects
Are You Capturing This Information?
1/19/99 © Johnson Controls, Inc. errorprf.ppt50
Identify Two Key LocationsIdentify Two Key Locations
Defect creation & discovery
points
1/19/99 © Johnson Controls, Inc. errorprf.ppt51
Review SOP atReview SOP atCreation PointCreation Point
Is there an SOP? Deviations?
Service Manual
I've been using Phillips head
screws!
I've been using slot head screws!
1/19/99 © Johnson Controls, Inc. errorprf.ppt52
Error-Proofing DevicesError-Proofing Devices
• Level 1 (Prevention: Ideal!) Eliminate error at the source
• Level 2 (Detection) Detects errors in the process of occurring, before it has become a defect
• Level 3 (Detection) Detects a defect after it has been made but before it leaves the station
1/19/99 © Johnson Controls, Inc. errorprf.ppt53
Prevent Defects by:Prevent Defects by:
• Shutdown (Level 1) - Processing stopped until error is
corrected.
• Controls (Level 1)- Only allowing parts to fit into jigs,
fixtures in the correct position.
1/19/99 © Johnson Controls, Inc. errorprf.ppt54
Error & Defect DetectionError & Defect Detection
•Error Detection (Level 2)– Detects errors as they are being
made.
•Defect Detection (Level 3) – Detects defects before they leave
station.
1/19/99 © Johnson Controls, Inc. errorprf.ppt55
Common DetectionCommon DetectionFunction & DevicesFunction & Devices
Detection Functions DevicePressure gauges, pressure-sensitive switchesTemperature thermometers, thermostats,
thermistors, thermocouplesElectric Current meter relays, current eyesVibration vibration sensorsCycles counters, stepping relays, fiber
sensorsTime times, delay relays, timing units,
time switchesInformation buzzers, lamps, flashing lamps
1/19/99 © Johnson Controls, Inc. errorprf.ppt56
Error-Proofing Devices:Error-Proofing Devices:Visual DevicesVisual Devices
1/19/99 © Johnson Controls, Inc. errorprf.ppt57
JigsJigs
Limit Switch
Desired Drilled Holes
Groove
Groove
Jig
IncorrectWorkpieceL/S
CorrectWorkpieceL/S
1/19/99 © Johnson Controls, Inc. errorprf.ppt58
Photoelectric Devices & OpticsPhotoelectric Devices & Optics
1/19/99 © Johnson Controls, Inc. errorprf.ppt59
Contact DevicesContact Devices
1/19/99 © Johnson Controls, Inc. errorprf.ppt60
CountersCounters
0 0 0 0 0 4
1/19/99 © Johnson Controls, Inc. errorprf.ppt61
ChecklistsChecklists
Packing Checksheet
Hubcap Covers (4)
Owner's Manual (1)
Radio Manual (1)
Floor Mats (4)
Tire Manual (1)
Plant Decal (1)
1/19/99 © Johnson Controls, Inc. errorprf.ppt62
Shop Floor ApplicationShop Floor Application
• Describe defect (error). (Write it down, draw it, etc.)
• Plot defect rate. (Pareto charts, histograms)
• Identify where defect is discovered and made• Detail SOP (What is SOP here?)• Identify deviations from SOP• Identify causes for deviations (Fishbone?
Brainstorming?)• Identify Red Flag conditions• Identify source errors• Propose ideas to eliminate or detect errors• Propose possible error-proofing devices
1/19/99 © Johnson Controls, Inc. errorprf.ppt63
SummarySummary
• Zero defects are possible if you build 100% inspection checks into every process.
• The production process can be designed to prevent & detect human errors.
• Team skills facilitate error-proofing.
1/19/99 © Johnson Controls, Inc. errorprf.ppt64
SummarySummary
• Source inspection & successive checking are the foundations of error-proofing.
• Error-proofing should be considered where an operation contains Red Flags.
• Error-proofing devices need not be expensive or high-tech.
1/19/99 © Johnson Controls, Inc. errorprf.ppt65
HAVE FUN!