Transcript Quality theories

Quality theories
Quality management
Lecture 3.
History of quality management
Early 1920
Scientific management (Taylor, Gilbreth)
1920s
Statistical process control (Shewart)
1930s
Acceptance sampling (Dodge, Roming)
1940s
Military standards introduced
1950s
Quality management in Japan (Deming,
Juran)
1960s
Taguchi method, and quality tools
1970s
Quality becomes strategic (USA)
1980s
Introduction of LEAN, TQM, Baldrige Award
1990s
Reengineering, Six Sigma
2000s
Supply chain management, improvement of
supplier development, LEAN, Six sigma
become popular, contingency theory
Quality and taylorism
• Basics of taylorism
– The whole process is divided into short steps (division of labor)
– It is not the worker who determine the process/movements -specialist do
that (task management)
– Workers are selected and trained for work
– Standard movements and tools, detailed instructions (standardization)
• Quality effects:
– Product and process design were separated from the repair of product
– Workers were not responsible for repairing of product
– Quality control department was established to control the product at
the end of the process
– The responsibility for quality were spread over in the company
Deming
• Not just worker but
managers have the
responsibility for
establishing quality
– Workers responsible for
special problems
– Managers responsible for
the whole system (proper
methods, equipments,
motivation system etc.)
• Quality improvement
must be divided between
the two level
Juran
• Quality problems are rooting in
insufficient and ineffective
planning for quality
• In traditional way:
– Planning determine the tools
for producing goods
– 20% of the operating process
is waste, it is planned into the
product or process
– Instead of quality improvement
they only do quality control
• Juran trilogy
– Planning
– Control
– Improvement
Ishikawa
• Democratizing statistics: everyone is responsible for
statistical analyzes,
• total involvement of the operating employees in
improving quality
• Basic 7 tools of quality
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Process map – flow chart, step of process
Check sheet – to collect errors for analyzes
Histogram – graphic representation of data
Scatter Diagrams – examine the relationship between variables
(what cause the problem)
– Control Chart – is the process stable or not
– Cause-and-effect (Ishikawa) diagram – find all reason of the
problem, directed tool for find all causes
– Pareto Chart – prioritize causes, determine problems must be
focused on
Feigenbaum
• Father of Total Quality
Control (TQC)
• the entire organization
should be involved in
quality improvement
• The quality is poor
– If the product is designed
incorrectly (engineering)
– If the product is released in
the wrong market
– If the customer relationship
is not proper. (marketing)
• 3 steps of improvement
• 4 deadly diseases
Crosby
• Crosby’s four theorem
– Quality is the conformance
to the requirements of
customers. The whole
system must be developed
according to this approach.
– The main goal is zerodefect. Do the right product
at the first time.
– Thus the applied method
for quality assurance is
prevention not control.
– Quality can be a source of
profit. Quality costs must
be evaluated, and on the
basis of these costs,
corrective actions should
take place.
Taguchi
• Quality definitions: quality is measured in terms of loss to
society if the service not performed as expected.
• Quality Loss Function (QLF): any deviation from target
value results in loss to society
• Robust Design: products should be designed to be
defect-free
– Concept design (technology and process choices)
– Parameter design (select parameters which have an effect on
quality – amount of training, heights of a paper)
– Tolerance design (deals with decrease variation in order to fulfill
the specification limits – use a higher-grade materials)
QLF (Qualtiy Loss Function)
• L=K*V2
– K – constant, and
– V2- mean squared dviation from target value
• K=C/T2
– C - unit repair cost
– T – tolerance interval
LSL Target value
USL
Exercise - QLF
• Suppose the cost to repair a radiator on an
automobile is $200. Compute the QLF for
losses incurred as a result of a deviation
from target setting where a tolerance of
6±0,5 mm is required and the mean
squared deviation from target is (1/6)2.
• Solution:
• K=200/0,52=800
• L=K*V2=800*(1/6)2=$22,22/unit
TAGUCHI PROCESS
• 1. Problem identification
• 2. Brainstorming session
– identify factors, its settings, interactions,
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Control factor
Noise factor
– Identify objectives
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The less is better
Nominal is best
The more is the better
• Experimental design
– Offline experimentation (number of replications)
• Experimentation
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Orthogonal array (determined by the number of factors and levels)
Record the result
Compute average performance for each factor
Showing the best outcomes
• Analysis (which level of each factor is the proper one)
• Confirming experiment (validate results)
Contingency theory
• There are no schemes, firms do not have
to use only one quality approach
• Successful firms adopt aspects of each
approach that help them improve,
understand them, and apply them
creatively.
• It depends on the situation which
approach is the best.
Thank you for your attention!