om lect 09(r3-jul 11)_quality management_basics_mms_sies
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Quality Management
N.K.Agarwal
Quality Management
• Product and service quality can be defined as – The total composite product & service
characteristics of marketing, engineering, manufacturing and maintenance
– Through which the product and service in use• Will meet the expectations of the customer
• Quality to industry means best for satisfying customer conditions
• Important among these conditions are– The actual end use– The selling price of product/service
Quality features of a Product
• Product features– Performance– Reliability– Durability– Ease of use– Serviceability
Quality features of a Product
– Esthetics– Availability of options and expandability– Reputation
• Freedom from deficiencies– Free of defects and errors at delivery,
during use and during servicing– Sales, billing and other business processes
free of errors
Quality features of Service
• Quality of a service judged by– Reliability– Availability– Credibility– Security– Competence of staff– Understanding of customer needs– Responsiveness to customers
– Courtesy of staff– Comfort of surroundings– Communication between participants– Associated goods provided with the service
• Freedom from deficiencies– Service free of errors during original and
future service transactions– Sales, billing and other business processes
free of errors
Quality features of Service
Quality Control (Q.C.)
• Procedures for meeting the goals• Generally 4 steps
– Setting standards– Appraising conformance– Acting when necessary– Planning for improvement
Statistical Quality Control (SQC)
• Application of the statistical techniques to accept or reject products already produced or to control the process, and therefore product quality while the part is being made.– Former is named as acceptance sampling– The later process called process control
• These are two prominent techniques of QC
SQC for Process Control• Based on probability theory• During manufacturing of identical parts, some are a little
large, some a little small but the average will be most frequent
• The smaller and bigger sizes are extremes from the average
• Bell or normal shaped curve obtained when frequency or counts of items by size plotted with size on the horizontal scale and count on the vertical scale
• In practice, SQC for process control done through control charts
• First developed by Dr. Walter A. Shewart of Bell Telephone Labs during 1930s
• Horizontal extensions of the bell shaped curve
Bell Shaped Curve
SIZE
NO
. O
F C
AS
ES
Control Chart
TIME
QU
ALI
TY
VA
RI A
TIO
N
LCL
CL AVERAGE QUALITY
UCL
Control Charts
• Types– Control charts for variables– Control charts for attributes
• Variables– Quality characteristics that can be measured
on a continuous scale ex: diameter of a shaft
• Attributes– Quality characteristics which can be classified
into one of the categories namely good or bad, defective or non- defective ex: an ammunition bullet
Control Charts
• Center line (CL): average quality• Upper and Lower control limits (UCL & LCL): also
called tolerance limits• Process is said to be stable or under control if the
quality of samples checked and variations plotted on the charts show the values within UCL and LCL
Control Charts
• Usually two types of information available from the charts– Whether the process is running under stable
condition or not i.e. Whether the process is under state of statistical control or not
– Whether the process is meeting the desired quality standards or not.
• If statistical control does not exist, it has to be established through technical control
• -R (MEAN-RANGE) CHART FOR VARIABLE CHARACTERISTICS– -R CHARTS HAVE TO EXIST AS A PAIR. INTERPRETATION OF
QUALITY OF THE ON-GOING PROCESS HAS TO BE DONE ANALYSING BOTH THE CHARTS TOGETHER
• PROCEDURE– CHOICE OF VARIABLE(X)– SELECTION OF RATIONAL SUB-GROUPS– CHOICE OF FREQUENCY– COLLECT K NUMBERS SUB-GROUPS ( USUALLY K=25) EACH OF
COVENIENT SAMPLE SIZE ‘n’ ( SAY 4-10)– FOR EACH SUB-GROUP, CALCULATE MEAN AND RANGE R– CALCULATE AVERAGE OF THE DIFFERENCE RANGES FOR ‘K’
SUB-GROUPS– COMPUTE CENTRAL LINE ( ), UCLR=D4* AND LCLR=D3* ,
WHERE D3 AND D4 ARE SAMPLE SIZE DEPENDENT CONSTANTS
X
X
X
RRR
- R CHARTX
• TEST FOR HOMOGENITY• IF SUB-GROUPS NOT HOMOGENOUS, REMOVE OUT OF
RANGE LIMIT SAMPLES AND COMPUTE MODIFIED R, UCLR AND LCLR TILL HOMOGENITY IS OBTAINED
• FOR HOMOGENOUS SUB-GROUPS( SAY K1), CALCULATE
X=X/K1 , COMPUTE UCLX = X+A2*R AND LCLX=X-A2R, WHERE A2 IS SAMPLE SIZE DEPENDENT CONSTANT
• TEST FOR HOMOGENITY FOR ALL INDIVIDUAL VALUES OF X FOR K1 SUB-GROUP WITHIN THE VALUES OF UCLX AND LCLX
• IF NON-HOMOGENOUS, REMOVE EXTREMES OUTSIDE
UCLX AND LCLX AND RECALCULATE X, UCLX AND LCLX
• CONSTRUCT X AND R CHART FOR RATIONAL SUB-GROUPS OBTAINED AFTER TESTING FOR HOMOGENITY
- R CHART…contdX
MEAN CHART
MEAN CHART
NO. OF SUBGROUPS
SA
MP
LE M
EA
N
LCL
UCL
X
X
X
X
X
1 2 3 4 K5 6 7 8
RANGE CHART
NO. OF SUBGROUPS
SA
MP
LE R
AN
GE
LCL
UCL
R
R
R
R
R
1 2 3 4 K5 6 7 8
Acceptance Sampling Techniques
• Best alternative of estimating quality of incoming/out going lots when 100% inspection not practical
• Sampling inspection necessary because of high cost of 100% inspection or destructive nature of inspection or testing
• Based on the premise that a sample represents the whole lot from which the sample is drawn
• Random sampling provides each element an equal chance of being selected and permit logical inferences to be made about the lot quality based on sample evidence
Acceptance Sampling
• Lot accepted or rejected based on the number of defects found in the sample
• No need to inspect the entire lot• Risks of accepting bad lots or rejecting good
lots always associated while making decisions based on sample evidence
Errors in Sampling
• Type-I error– An error when a sample from the output of a
process may lead to conclusion that the process is out of control, when in fact, it is operating as intended: Producer’s risk ()
• Type-II error– An error when sample leads to conclusion
that the process is satisfactory , when in fact, the process is not working as intended: Consumer’s risk ()
Total Quality Management
• A philosophy that involves everyone in the organisation in a continual effort to improve quality and achieve customer satisfaction
• With TQM, the whole organisation works together to guarantee product quality
• The aim is to make products of perfect quality- with Zero Defect
TQM- Principles
• Three important principles– Customer satisfaction– Employee involvement– Continuous improvement in quality
• Deming's 14 points to serve as guidelines for quality management– Create constancy of purpose for continual
improvement of product & service– Adopt the new philosophy for economic
stability– Cease dependency on inspection to
achieve quality
Deming Philosophy
– End the practice of awarding business on price tag alone
– Improve constantly & for ever the system of production & service
– Institute training on the job– Adopt & institute modern methods of
supervision & leadership– Drive out fear– Break down barriers between departments
& individuals
Deming Philosophy
– Eliminate the use of slogans, posters & exhortations
– Eliminate work standard & numerical quotas
– Remove barriers that rob the hourly worker of the right to pride in workmanship
– Institute a vigorous program of education & retraining
– Define top management’s permanent commitment to ever-improving quality & productivity
Deming Philosophy
Quality Management
• Quality of a Product or Service must meet or exceed the customers expectation Quality in the organisation has to be built into the organisation in stages
• Statistical Quality Control can be applied to the products under processing as well as manufactured lots in large quantities
• Total Quality Management aims at – Customer satisfaction– Employees involvement, and – Continuous improvement in quality
Thank You
References
• TOTAL QUALITY CONTROL :
ARMAND V. FEIGERBAUM• PRODUCTION AND OPERARTIONS
MANAGEMENT : ASWATHAPPA• PRODUCTIVITY TECHNIQUES :
GONDHALEKAR/SALUNKHE• OPERATIONS MANAGEMENT : DONALD
WALTERS• TOTAL QUALITY MANAGEMENT :
K.SRIDHARA BHAT
ASSIGNMENT VII-QUALITY MANAGEMENT
• Discuss “Quality is what the customer wants”. How is this implemented ?
QUALITY CONTROL
• Total Quality Control (TQC)– An effective system for integrating the
quality development, quality maintenance and quality improvement efforts of the various groups in an organisation so as to enable marketing, engineering, production and services at the most economical levels which allow for full customer satisfaction
EVOLUTION OF TQC
• Quality Assurance (QA)– QA includes QC and also refers to emphasis on the
quality in the design of products, processes and jobs, in personnel selection and training
• Inspection– The act of determining conformance or otherwise of the
expected performance– Basis of inspection is usually a specification which is
called inspection standard– Inspection is made by comparing the quality of the
product to its standard
CONTROL CHART FOR ATTRIBUTES• CONSTRUCTION OF ‘np’ (NUMBER OF DEFECTIVES CHART) CHART FOR
CONSTANT SAMPLE SIZE ‘n’
SAMPLE SIZE=n,
NUMBER OF SUB-GROUPS=K,
NUMBER OF DEFECTIVES PER SUB-GROUP=C
FRACTION DEFECTIVE p=C / n
CALCULATED FOR EACH SUB-GROUP i.e.p1=C1/n, p2=C2/n, ……. pk=Cn/K
AVERAGE FRACTION DEFECTIVE p=p/K = (p1+p2….pk)/K
OR p= (C1/n+C2/n……CK/n)/K
= (C1+C2……..CK)/(n*K) =C/(n*K)
CENTRAL LINE =n*C/(n*K)
UCL= +3 (1-p)LCL= -3 (1-p) =ZERO, IF NEGATIVE
TEST FOR HOMOGENITY DONE AS IN (X-R) CHART.
pnpn
pn
pn pn
np OR c CHARTnp
OR
c
LCL
UCL
PCL= COR
‘p’ CHARTS
• ‘ p ‘ CHARTS(FRACTION DEFECTIVE CHART) FOR VARYING SAMPLE SIZE
– DATA COLLECTED GIVE SAMPLE SIZE(n1,n2,…….nk) FOR K SUB-GROUPS AND VALUES OF NUMBER OF DEFECTIVES(C1,C2,C3…..Ck)
– FRACTION DEFECTIVES FOR EACH GROUP CALCULATED AS:
p1=C1/n1, p2=C2/n2 ….pk=Ck/nk
CENTRE LINE p=p/k=(p1+p2….pk)/K
UCL FOR EACH SUB-GROUP = p+3p(1-p)]/ SAMPLE SIZE
LCL FOR EACH SUB-GROUP = p-3p(1-p)]/ SAMPLE SIZE=ZERO,IF NEGATIVE
– AS SAMPLE SIZE VARIES FOR EACH SUB-GROUP, THERE WILL BE AS MANY VALUES OF LCLs AND UCLs AS THE NUMBER OF VALUES OF SAMPLES ARE (i.e. n1, n2……..nk)
np OR c CHART
‘ C ‘ CHARTS
• ‘ C ‘ CHARTS( NUMBER OF DEFECTS CHART) FOR CONSTANT SAMPLE SIZESAMPLE SIZE= n
NUMBER OF DEFECTS EXISTING IN ALL THE SAMPLES IN EACH SUB-GROUP FOR K SUB-GROUPS ARE SAY C1, C2 ….Ck
CENTRE LINE(CL) C=C/K
=(C1+C2+……CK)/K
UCL FOR EACH SUB-GROUP=C+3C
LCL FOR EACH SUB-GROUP=C- 3C =0, IF NEGATIVE
‘U’ CHARTS
• ‘U’ CHARTS( NUMBER OF DEFECTS/UNIT) FOR VARYING SAMPLE SIZE– DATA COLLECTED REGARDING SAMPLE SIZE AND NUMBER
OF DEFECTS IN ALL THE SAMPLES FOR EACH OF K SUB-GROUPS
– SAMPLE SIZE n1,n2….nk– NUMBER OF DEFECTS PER SUB-GROUP
=U=C/n=C/SAMPLE SIZE
i.e. U1=C1/n1, U2=C2/n2…….Uk=Ck/nk
CENTRE LINE CL=U=U/K=(U1+U2+…UK)/K
UCL FOR EACH SUB-GROUP=U+3U/SAMPLE SIZE
LCL FOR EACH SUB-GROUP=U-3U/SAMPLE SIZE=ZERO, IF NEGATIVE
• Two key philosophies in TQM– A never ending push to improve ( i.e.
continuous improvement or Kaizen in Japanese) , and
– A goal of customer satisfaction which involves meeting or exceeding customer expectation
Total Quality Management
Implementation of TQM
• Get top management commitment• Find out what the customer wants• Design products with quality in mind• Design the process with quality in mind• Build teams of empowered employees• Keep track of results• Extend these ideas to suppliers & distributors
TQM - Failure
• Lack of commitment from top management• Focusing on specific techniques rather than
on the system• Not obtaining employee buy-in & participation• Program stops with training• Expecting immediate results, not a long term
pay-off• Forcing the organisation to adopt methods
that are not productive or compatible with its production system & personnel