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Quality Management
© Holmes Miller 1999
Based on slides for Chase Acquilano and Jacobs, Operations Management, McGraw-Hill
Definitions of Quality
ASQC: Product characteristics & features that affect customer satisfaction
User-Based: What consumer says it isManufacturing-Based: Degree to which a
product conforms to design specificationProduct-Based: Level of measurable
product characteristicExercise: List attributes of a quality
car
Importance of QualityCosts & market share
Market GainsReputationVolumePrice
Lower CostsProductivityRework/ScrapWarranty
ImprovedQuality
IncreasedProfits
Total Quality Management
Managing the entire organization so that it excels on all dimensions of products and services that are important to the customer.Involves entire organization from supplier to
customerObjective: Meet or exceed customer needs
through company-wide continuous improvement
Early proponentsW. Edwards DemingJ. M. JuranPhilip B. Crosby
Some Total Quality Management Principles
Continuous improvementEmployee empowermentBenchmarkingKnowledge of TQM tools
1. Plan a change aimed at improvement.
1. Plan
2. Execute the change.
2. Do
3. Study the results; did it work?
3. Check
4. Implement the change; abandon it or do it again.
4. Act
CI Methodology: PDCA Cycle (Deming Wheel)
Employee Empowerment
Getting employees involved in product & process improvements85% of quality problems are due to process &
material Techniques
Talk to workersSupport workersLet workers make decisionsBuild teams & quality circles
Benchmarking
Learn “best practices”Form Benchmarking teamsHow might Muhlenberg go about
benchmarking? What topic might be “benchmarked”?
Quality Tools
Quality function deployment (QFD)Taguchi techniquesPareto chartsProcess chartsCause & effect diagrams Statistical process control (SPC)
Pareto Chart
Vertical bar chart showing relative importance of problems or defects Makes identifying & solving them easier
Based on Pareto PrincipleMost effects have relatively few causese.g., 80% of quality problems come from 20%
of machines, materials, or operatorsFocus on ‘vital few’ 20% causesCalled 80-20 rule
Process Chart Example
SUBJECT: Request tool purchase
Dist (ft) Time (min) Symbol Description
D Write order
On desk
75 D To buyer
D Examine
SUBJECT: Request tool purchase
Dist (ft) Time (min) Symbol Description
D Write order
On desk
75 D To buyer
D Examine
= Operation; = Operation; = Transport; = Transport; = Inspect; = Inspect; D = Delay; D = Delay; = Storage = Storage
Cause & Effect Diagram Example
MethodMethod ManpowerManpower
MaterialMaterial MachineryMachinery
DrillDrillDrillDrillOverOverOverOverTimeTimeTimeTime
SteelSteelSteelSteel
WoodWoodWoodWood
LatheLatheLatheLathe
TiredTiredTiredTired
Too many defects
Too many defects
OldOldOldOld
SlowSlowSlowSlow
ExerciseIn your group, select a problem:
At MuhlenbergYour companyAnother organization
Develop a cause and effect diagram to address the problem
Deliverable: Develop the diagram and share solution with class
Statistical Process Control (SPC)
Uses statistics & control charts to tell when to adjust process
Developed by Shewhart in 1920’sInvolves
Creating standards (upper & lower limits)Measuring sample output (e.g. mean weight)Taking corrective action (if necessary)
Done while product is being produced
970
980
990
1000
1010
1020
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
LCL
UCL
Can be used to monitor ongoing production process quality and quality conformance to stated standards of quality.
Can be used to monitor ongoing production process quality and quality conformance to stated standards of quality.
Example: Control Charts
Aspects of Statistical Process Control
Process VariationKey Point: ANY process has associated
variationProcess Capability
Some processes are not capable of satisfying customer requirements
Process Control ProceduresVariable data
72” in height, 131 lbs.Attribute data
On/Off, 7 scratches on surface
Basic Forms of Variation
Assignable variation is caused by factors that can be clearly identified and possibly managedtemporary employeeimproperly set machine
Common variation is inherent in the production processphone system cannot handle incoming traffic
-- slow response times
Six Sigma Quality
A philosophy and set of methods companies use to eliminate defects in their products and processes
Seeks to reduce variation in the processes that lead to product defects
The name, “six sigma” refers to the variation that exists within plus or minus six standard deviations of the process outputs
Six Sigma allows managers to readily describe process performance using a common metric: Defects Per Million Opportunities (DPMO)
1,000,000 x
units of No. x
unit per error for
iesopportunit ofNumber
defects ofNumber
DPMO 1,000,000 x
units of No. x
unit per error for
iesopportunit ofNumber
defects ofNumber
DPMO
Six Sigma Quality: DMAIC Cycle
Define, Measure, Analyze, Improve, and Control (DMAIC)
Developed by General Electric as a means of focusing effort on quality using a methodological approach
Overall focus of the methodology is to understand and achieve what the customer wants
Inspection
Involves examining items to see if an item is good or defective
Objective: Detect a defective productDoes not correct deficiencies in process or
productIssues
When to inspectWhere in process to inspectConsider Transformation Process ---
Transformation Process -- Revised View
Inputs Transformation Process Outputs Customer
Inspect Inspect Warranty
Good- will
Rework Scrap
These are the additional costs of quality!
CONTROL CHARTS
External Failure Costs
Appraisal Costs
Prevention Costs
Internal FailureCosts
Costs ofQuality
Costs of Quality
Funnel Experiment (Deming)Treating a special cause as a common cause Improvement of a stable system nearly always
means reduction of variation -- -- it may also require moving the center line to
a higher or lower level.Tampering with a stable system only increases
the production of faulty items and mistakes.One necessary qualification of anyone in
management is -- -- stop asking people to explain ups and downs
that come from random variation.