Transcript

• 1. STATISTICAL QUALITY CONTROLAnubhav Grover (12HM08)
• 2. OPERATION PROCESS The goal of every operation or production system isto generate a useful product. The product may be a service, information, orphysical object. Each production cycle begins with inputs that aretransformed by a process into a more desired stateor into the product.
• 3. NEED OF QUALITY CONTROL In each process, excessive variations and errorscan cause nonconformities, which leads to threeundesirable consequences: (a) scrapped or wasted resources; (b) degraded process throughput; (c) “contamination” from undetectednonconformities, reducing the value of the product to the customer.
• 4. GOAL OF QUALITY CONTROL The goal of quality control in every productionsystem is to (a) eliminate nonconformities and theirconsequences, (b) eliminate rework and wasted resources, and (c) achieve these goals at the lowest possible cost
• 5. QUOTES BY PHILIP CROSBY Four interesting quotes fromQC expert Philip Crosby. 1. “The cost of quality is theexpense of doing thingswrong.” 2. “There is absolutely noreason for having errors ordefects in any product orservice.” 3. “If quality isn‟t ingrained inthe organization, it will neverhappen.” 4. “It is much less expensiveto prevent errors than to re-work, scrap, or service them.”
• 6. EVOLUTION OF QUALITY CONTROL Most quality-control methods were initiallydeveloped to aid manufacturing. High- volume production typically requires manyrepetitions involving a controlled sequence ofoperations. Where operations are frequently repeated, it iseasier to recognize processing errors and identifyappropriate control measures
• 7. JUDGMENT INSPECTIONS Historically, the first quality-control methods werebased on judgment inspections. Judgment inspections are made after a process hastransformed inputs into a product. Based on inspection, the product is accepted,rejected, or reworked.
• 8. JUDGMENT INSPECTION
• 9. SQC INSPECTIONS The next major breakthrough in quality control wasmade by a team led by Shewhart at BellLaboratories. His team demonstrated that variation on theproduction floor could be described statistically andthat statistical data could identify when a processwas drifting out of control. Statistical data were useful in guiding adjustment ofthe process to reduce the probability thatnonconforming product would be produced.
• 10. SQC INSPECTIONS
• 11. SQC OVER JUDGMENT INSPECTION The SQC inspection process had many advantagesrelative to judgment inspections. SQC relies on sampling inspection, whichsubstantially reduces the amount of inspectionactivity. Unlike judgment inspection, SQC provides afeedback for the production process that helps toreduce the likelihood of nonconformities. The improvement in quality achieved through SQCreduced rework, scrap, and wasted resources.
• 12. SQC Statistical Quality Control began in the 1930`s withthe industrial use of control charts. By implementing SQC, the United States (andBritain) were able to produce supplies at lower costand in large quantity. This was the origins of Statistical QualityManagement and Japan`s quality improvementprocess journey.
• 13.  A control chart contains A center line An upper control limit A lower control limit A point that plots within thecontrol limits indicates theprocess is in control A point that plots outside thecontrol limits is evidencethat the process is out ofcontrol There is a close connectionbetween control charts andhypothesis testingControl Chart
• 14. REASONS FOR POPULARITYOF CONTROL CHARTS1. Control charts are a proven technique forimproving productivity.2. Control charts are effective in defectprevention.3. Control charts prevent unnecessary processadjustment.4. Control charts provide diagnostic information.5. Control charts provide information aboutprocess capability.
• 15. HOW IS SQC USED IN MANUFACTURING It is based on statistical techniques of sampling. That isby using small samples companies determined thequality level[defective rates] of the whole production run. In SQC, a random sample of finished products ismeasures against predetermined standards. Hence, the deffective rate of a production run of100,000 units might be decided by a sample of fewhundred units. In SQC, the margin on error in testing the sample canbe established at the 90.95, or 99 percent level.
• 16. HOW IS SQC USED IN MANUFACTURING Based on the results of the sample, a techniciantesting a batch would conclude that the defectiverate was too high and it fell within the boundary oftolerance at the 95 significance level. Based on the sample test, the quality controltechnician would either accept the whole batch orreject it. If the technician were to reject the sample a checkof the whole production batch would have to bedone to remove the defective units from the batch.
• 17. TOYATA „S ADVANTAGE OF USING SQC Based on the corporatephilosophy of customerfirst and quality firstsince its founding, Toyota Motor Co., Ltd.won the DemingApplication Prize in 1965and the Japan QualityControl Award in 1970, following the introductionof statistical qualitycontrol (SQC) in 1949.
• 18. STATISTICAL QUALITY CONTROL INSERVICES Statistical quality control (SQC) tools have beenwidely used in manufacturing organizations forquite some time. Manufacturers such as Motorola, General Electric,Toyota, and others have shown leadership in SQCfor many years. Unfortunately, service organizations have laggedbehind manufacturing firms in their use of SQC. The primary reason is that statistical quality controlrequires measurement, and it is difficult to measurethe quality of a service. Services provide an intangible product and thatperceptions of quality are often highly subjective.
• 19. SQC IN SERVICES Another issue that complicates quality control inservice organizations is that the service is oftenconsumed during the production process. The customer is often present during servicedelivery, and there is little time to improve quality. The way to manage this issue is to provide a highlevel of workforce training and to empower workersto make decisions that will satisfy customers.
• 20. SQC AT RITZ CARLTON HOTEL One service organization that has demonstratedquality leadership is The Ritz-Carlton HotelCompany This luxury hotel chain caters to travellers who seekhigh levels of customer service. The goal of thechain is to be recognized for outstanding servicequality. To this end, computer records are kept of regularclients‟ preferences. To keep customers happy,employees are empowered to spend up to $2,000on the spot to correct any customer complaint.
• 21. RITZ CARLTON ADVANTAGE OF USING SQC The Ritz-Carlton has received a number ofquality awards including winning the MalcolmBaldrige National Quality Award twice.
• 22. THANK YOU