02 - DMAIC
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Transcript of 02 - DMAIC
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Session 2: DMAIC Problem Solving
Pat Hammett, Univ of Michigan 1
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DMAIC Problem Solving Process
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Topics
I. Identifying Six Sigma Project Opportunities
II. Six Sigma Problem Solving Method DMAIC Methodology
III. Case Study Mold Changeover Process
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I. Identifying Six Sigma Project Opportunities
Start with your customer! External one who pays the bills Internal (Next Process Customer) next process that receives work
where possible, focus on Core Customers
External Customer Driven Projects Reactive to customer concerns / complaints (find & fix) Proactive to customer desires (strategic projects)
Internal Pain Projects Internal processing projects resulting from poor product-service
design or poor processing performance Value Stream Mapping (Flow-Variation Concerns)
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Six Sigma Project Examples
Manufacturing Operations Project Examples Conformance to customer use/ specifications (warranty reduction, customer satisfaction
projects) Conformance to internal product specifications (rework and scrap) Operational efficiency (processing time, material usage, equipment and facility usage)
Business Operations/ Transactional Project Examples Call Centers (response/ resolution time) Customer Ordering Systems (order time to delivery, order accuracy) Management Reporting (time/cost to prepare management reports) Design Process (CAD Release Errors, Drawing Completion Time) Customer complaints (call center, service center, etc.) Internal Business Processes (payroll systems, mail systems, accounting systems, working
capital improvement) Order System Processing (internal processing time/errors) Application Processing (internal approval process) IT Systems (information flow, complaints) Human Resource Management (staffing, training, benefits analysis) Retail Services (wait time, customer satisfaction) Hospital Systems (patient flow, operational efficiency, wait time)
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II. Six Sigma DMAIC Methodology
We often find it useful to utilize a generic process to successfully execute continuous improvement projects
Some commonly used Problem-Solving Processes: Six Sigma: Define Measure Analyze Improve Control TQM: PDCA ~ Plan Do Check Act Red X Strategy Engineering Method A3 Problem Solving Process, etc.
All of these have been applied successfully (and unsuccessfully)
This course will focus on Six Sigma DMAIC!
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DMAIC Problem Solving Method
DMAIC (deh-MAY-ihk) Define identify improvement opportunity Measure measure current state of the process Analyze identify causes of variation/ defects Improve develop and implement solutions Control install controls to prevent future defects
Like many other methods, DMAIC provides a robust structure to problem solving
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DMAIC Roadmap (Tools & Methods)
Improve(implement solution)
Control(establish plan to
prevent reoccurrence)
Identify Projects (based on QCD) Project Charter High Level Process Map/
Value Stream Map
Assess Current State of Key Output Variable (graphical and numeric)
Data pattern Process Capability/DPMO Process Stability
Measurement Systems Analysis (MSA) Identify key input variables
Measure(current state of Y)
Implement recommendations from analysis studies. (e.g., establish controls, determine optimal Settings)
Develop new process flow Implement lean counter
measures (standardized work, visual control, poka yoke)
Verify findings and pilot
Establish Control Plan Verify Project
Analyze(find key Xs)
Qualitative Process Analysis Process Mapping Potential variation causes
(e.g., Cause-Effect Diagram) Quantitative Process Analysis
Using statistical methods to determine key Xs and their effect (relationship)(e.g., Pareto Drill Down Analysis, Regression, Hypothesis Tests)
Prioritize key input variables
Define(improvement opportunity)
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III. DMAIC Case Study Head Lamp Manufacturing
Mold Changeover Reduction
Adapted from project by Don Lynch
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Headlamp Value Stream Map Analysis(Can you identify some improvement opportunities?)
Bodies
Lens
CT 65 S..Uptime 89% C/O 30 M.FTT 92%
CT 120 S.Uptime 84% C/O 3.54 H.(budget 2.5 H)FTT 95%
CT 45 S..Uptime 92% C/O 20 M.FTT 89%
CT 60 SUptime 98% C/O 30 M.FTT 95%
1 Day
60 sec.
3 Day5 Day
120 sec.
5 Day
65/45 sec.
14 Day
245 sec.
Big CarPlastic.
Vacuum Metal
I
I
I I
I
I
_5_/wk
Molding
Assembly
Coating
MPL6 week
Daily
6 week
Weekly
Weekly
Weekly
Weekly/Daily
Raw Matl Ship~14 days
~Value-add time~245 seconds
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Problem Background
Problem Background: Injection molding department is a bottle neck in head lamp assembly. A major issue is production losses due to excessive total changeover time both length of changeover and number of changeovers.
Current Performance Information: -Average Mold changeover=3.54 hours (historical data)
Budget Time < 2.5 hours - 3 changeovers/week per machine on average * 34 machines - Total lost production= 100 hours per week
Defect Definition:Any changeover taking more than the budgeted 2.5 hours
Question: Is this a product improvement orbusiness process improvement project?
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Define Phase Define improvement opportunity
Problem Statement Description of problem. Time period of problem. Magnitude of the problem and its impact on business performance,
in $$ if possible. Project Priority may include a Pareto Chart or other analysis to
justify why project has been selected over other opportunities.
Identify project improvement goal Goals should be SMART
Specific, Measurable, Attainable, Relevant, Time Bound
Identify project scope Should be able to complete project in 4-6 months
Usually summarize the above in a Project Charter
D M A I C
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Sample Project Charter Form Project Charter Template
Project Charter Template
Project Information ResourcesProject #: Project Leader:Project Name: Mold Changeover Reduction Black Belt: C. KramerProject Start Date: Champion:Project End Date: Process Owner: A. Vandolay
Problem Statement:
Goal Statement:
Project Scope
Excessive number of mold changes and mold changeover time per change resulting in excess labor hours vs. budget, scheduling problems, excess inventory, etc. This has been a chronic problem and is costing over $150K/year.
Team Members:
Eliminate mold change-overs taking longer than 2.5 hours.
Focus on reducing the number of changeovers and time per changeover for the 34 mold machines in the headlamp lens molding department.
W. Neuman, G. Constanze, E. Benes, B. Sakamana, T. Whatley
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Projected Savings(selling the project business case)
Is this project worth pursuing as a Six Sigma project?
D M A I C
Item Value
Actual Changeovers/Week 102Budgeted Changeovers/Week 60Actual Hours/Changeover 3.5Budget Hours/Changeover 2.5Weeks per year 47Total DL Rate 34.47
Lost Annual Hours (excess changeover time) $165,249Lost Annual Hours (excess # of mold changes) $170,109
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Measure Phase
Observe the Process First! (talk to the operators involved)
Map the Process of interest
Establish the Current State (baseline performance level). Key Tasks: Assess process stability and data patterns
1.Time Order (use run chart or statistical process control chart) Is problem sporadic (special cause) or chronic (consistent)?
2.Non-time order (use histogram or box plot) Is problem related to high variation, mean off target, or both?
Assess process capability (as DPM/DPMO*, Yield, Cp/Cpk) Mold Case: 80% of changeovers take longer than 3.5 hours
Assess measurement system capability
D M A I C*DPM = Defects per million; DPMO = Defects per million opportunity
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Dept. 682
Put machinein manual
Disconnect material feed
lines & run out material
Turn off mold heaters
Lower Mokon temp
Turn off power to injection
units
Disconnect water, air, hydraulic,
electrical lines
Remove mold Repair? Take mold to tool room
Yes
Return mold to rack in dept.
No
Get new mold from rack (or
tool room)
Install new mold
Reconnect water, air, hydraulic,
electrical lines
Turn on mold heater
Set Mokon Temp
Hook up material lines on mezzanine
Verify Program Settings
Start production
Quality Part?
Continue Production.
Inform Supervisor
Yes
Make Adjustments
No
D M A I C
Process Map Changeover
Process
Baseline -- current changeover process
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Sporadic vs. Chronic Problems
Sporadic Problems exist when unexpected changes in normal process operations occur (special cause variation) Typical Solution:
Chronic Problems exist when processes normally operate at an unacceptable level of common cause variation Typical Solution:
time
Consistent, but bad.
time
Y
Y
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Process Stability (Predictability over Time)
Comments Data in time order using a statistical process control chart (or run chart) Initial hypothesis -- only a few molds were causing problem (sporadic)Do these data support this hypothesis Or, is this problem chronic?
Individuals Chart
-0.070
3.542
7.153
-1.0
1.0
3.0
5.0
7.0
1 16 31 46 61 76 91 106 121 136 151 166 181 196 211 226 241 256 271 286 301
Subgroup
Indi
vidu
al V
alue
ControlLimit
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Process Distribution/Capability --Mold Changeover Time
Current State: average changeover time is 3.5 hours with a standard deviation of 1.1 (estimated DPM: ~817K)
Is distribution Normal (Bell-Shaped)? Mean and/or variation problem?
IMPLICATIONS?
Average StDev Yield3.5 1.1 18%
Individuals Chart
-0.070
3.542
7.153
-1.0
1.0
3.0
5.0
7.0
1 16 31 46 61 76 91 106 121 136 151 166 181 196 211 226 241 256 271 286 301
Subgroup
Indi
vidu
al V
alue
Histogram Changeover Time
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-0.05 0.00 0.05 0.10
Dif f erences
Boxplot of Differences(with Ho and 95% t-confidence interval for the mean)
[ ]X_
Ho
Measurement System Validation
Measurement system was evaluated by sampling 30 changeovers and comparing system results to actual timed results
D M A I C
Paired T-Test and CI: Computer, SamplingPaired T for Computer - Sampling
N Mean StDevComputer 30 3.772 1.367Sampling 30 3.766 1.358Difference 30 0.00633 0.03211
P-Value = 0.289
Is there a significant difference?
Why is this important to verify?
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Analyze Phase
Identify sources of variation / causes of defects or nonconformities
Identify the vital few key process input variables that affect key outputs -- Find the knobs
Use simple analysis tools first; apply complex tools as necessary. Be careful of too much data
Two Phase Approach Qualitative Analysis identify potential causes Quantitative Analysis perform statistical data analysis to
identify key X factors, robust ranges for key X variables, etc.
D M A I C
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Qualitative Analysis: Cause-Effect Diagram Example
Inefficient Changeovers
Maintenance avail.
Hose installation
Mold availability
Program set-up
PMEA availability
Knockout pins
Travel time
Mokon leaks
Mokon heating
Mokon malfunctions
Pick offs
Dryer
Hot runners
Bad fittings
No central storage
No standardization
Material change
PMEA training
Procedure
Mold cart
Lack of floor space
Mold racks
Excess dunnage
Man
Machines
Materials
Methods
Measurements
Environment
Dedidated, Efficient Changeovers
D M A I C
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Quantitative Analysis:Factors to Investigate
Factors or Variables to Study Differences by Individual Mold (Mold ID) Shift-Shift Differences Specific changeover tasks
Given data pattern identified in current state analysis, which of these are least likely?
D M A I C
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Analyze PhaseMultiple Box Plot: Stratification Analysis
Findings: Changeover not dependent on individual mold ID No statistically significant difference (based on mean test p-value) Note: line in center of box is median time by mold ID
Box Length50% of
Setups by ID
One Way ANOVAp-value 0.859
D M A I C
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Analysis by Shift
Findings: No difference
Implication?
Stratification Analysis by Shift
D M A I C
Analysis of Variance Time by SHIFTSource DF SS MS F SHIFT 2 1.14 0.57 0.29Error 120 234.26 1.95Total 122 235.40
p-value 0.747
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Others
Other w
ait t im
e for m
old
Wait t
ime fo
r main
tenanc
e servi
Verify
sett ing
s, prod
uce par
ts
Install
mold
Heat ing
proce
ss
Wait t
ime fo
r cart
985.6152.0190.0196.0200.0490.0580.035.3 5.4 6.8 7.0 7.217.520.8
100.0 64.7 59.3 52.5 45.5 38.3 20.8
2000
1000
0
100
80
60
40
20
0
DefectCount
PercentCum %
Perc
ent
Coun
t
PARETO OF TOP TIMED TASKS_ QUICK MOLD SETS
Top two factors:
Waiting time for carts - 21%
Heating process - 18%
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Analyze Phase
D M A I C
Top two causal factors (waiting for changeover cart and heating process) accounted for ~40% of total time or an average of 1.3 hours per changeover
Of the setup tasks, ~half of the actions could be completed with prior mold still running (external)
Other actions (and almost half of the average total time) required mold to be down when performing
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Improve Phase Improve phase is also known as the DO phase
Purpose of the improve phase is to make changes to a process to reduce/eliminate: defects, time, and costs
Improve countermeasures often have a dual purpose: Identify a better way (operating conditions) Identify a better system to maintain the better way (control)
D M A I C
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Some Common Improve Phase Types of Countermeasures
Implement one or several of the following actions to improve performance of key Y metric1. Improve Training and Empowerment2. Implement New Standardized Work Practice3. Redesign/Improve Process Flow
Batch Reduction or Elimination Change Process Layout (e.g., Cellular Teaming Concept)
4. Change (Optimize) a Process Input or Setting(s)5. Implement Quality at the Source 6. Install Mistake Proofing Device (Poka-Yoke)7. Install New Process Monitoring Systems
Visual Controls & Management to quickly identify defects Implement new data collection system
D M A I C
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Recommendations - Case Study
Implement Recommendations from Case Study
Case Study: Improvements completed in 3 phases Phase I Address top two: heating process and wait for cart
Scheduling of mold changes was changed to coincide with breaks Time for heating was hypothesized to go from 0.62 to 0.12 hours
Optimum number of carts calculated and additional cart was purchased Time waiting for carts was hypothesized to go to zero
Phase 2 Take more actions external to mold changeover time
Phase 3 Streamline internal actions
D M A I C
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Improve Phase - Verification
D M A I C
reduction over time by phase
Did phase 3 have a significant impact?
0
1
2
3
4
5
6
7
Tota
l
Boxplot of Changeover Time
(means are indicated by solid circles)
Base Phase I Phase II Phase III
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Verification Process Capability
Ran changeovers with new process across all molds Then, calculated Actual Savings: ~$200K
Average StDev YieldOriginal 3.5 1.1 18%Post Improve 1.4 0.5 98%
D M A I C
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Control Phase
Control (and Verification) Phase install mechanisms or processes that prevent the re-occurrence of problems
Add audit to ensure compliance to standard operating procedures Add audit/control plan for suppliers. Install poka-yoke devices to identify defects/errors as they occur (e.g.,
automatic error proofing system) Install new process monitoring system/ IT system
Control phase involves the development, documentation, and implementation of a process control plan. Advanced Product Quality Plan (APQP) Guidelines (used by Auto Industry) ISO 9000 Guidelines
Effectiveness of control plan must be verified through long term study
D M A I C
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Control Phase - Case Study
D M A I C
Case Study Examples: Phase 1 Address the top factors (cart and heat process)
Purchase and receipt of additional changeover cart Change mold changeover process to heat during lunch when
possible (new standardized work practice) Process monitoring chart of changeover time
Phase 2 Take external actions outside of mold changeover Assignment of new labor standards for changeover team Change control plan/standardize work for mold changeover process
to convert external actions to occur outside of press Instruction of team to new process
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Project Viewed in Hindsight
Hmm, these project solutions seem obvious!
Recall, initial team beliefs
Follow Up: Why dont people just follow standardized work in the first place?
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Key Case Study Takeaways
Importance of characterizing a problem with data Evaluate if Mean and/or Variation Problem Assess if Sporadic or Chronic Problem
Analysis (Avoid Fatal Leap from Problem Solution) Importance of Systematic Problem Solving Decomposing Overall Variation into Sources Statistical & Practical Significance
Improve Phase Dual Purpose Improve and Control Let the data drive the solution
DMAIC with an R Replicate solutions to other problems
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Key Learning Items
Understand DMAIC Process DEFINE-MEASURE-ANALYZE-IMPROVE-CONTROL Understand key tasks/objectives of each phase
Note: cover in more detail throughout the course
Create a project charter Problem Statement
Description of problem, Time period of problem, and Magnitude of the problem and its impact on business performance, in $$ if possible
Stakeholders, Goal, and Scope
Understand difference between sporadic and chronic problem