STATISTICAL PROCESS CONTROL

Statistical process control (SPC) is a method of quality control which uses statistical methods. SPC is applied in order to monitor and control a process. Monitoring and controlling the process ensures that it operates at its full potential. At its full potential, the process can make as much conforming product as possible with a minimum (if not an elimination) of waste (rework or scrap). SPC can be applied to any process where the "conforming product" (product meeting specifications) output can be measured. Key tools used in SPC include control charts; a focus on continuous improvement; and the design of experiments. An example of a process where SPC is applied is manufacturing lines.

1. STATISTICAL PROCESS CONTROL(SPC) by , Vivek B. Thorve

2. CONTENTS INTRODUCTION OBJECTIVE OF SPC PROCESS CONTROL VARIATION CAUSES STATISITICAL CONTROL TOOLS FOR STATISTICAL CONTROL PROCESS CAPABILITY CONTROL CHART TYPES CONTROL CHART MEHODOLOGY EVALUATION ADVANTAGES LIMITATIONS APPLICATIONS CONCLUSION REFERNECES Statistical process control

3. INTRODUCTION Statistics - A way to collect, classify, present and interpret numerical data (information expressed in numbers). Process - A combination of machines, equipment, people, raw materials, methods and environment that produces a product. A process is how something gets done. Control - Directing or regulating a process so that it behaves the way it is meant to behave. So SPC is the use of numerical data to direct or regulate the methods used to produce a finished product . SPC is applied in order to monitor and control a process. Monitoring and controlling the process ensures that it operates at its full potential. Statistical process control BACK

4. OBJECTIVE OF SPC Increases customer satisfaction. Decreases scrap, rework, and inspection costs. Decreases operating costs. Improves productivity. Sets a predictable and consistent level of quality. Eliminates or reduces the need for inspection by the customer. Statistical process control BACK

5. PROCESS CONTROL THREE TYPES OF PROCESS CONTROL PREVENTION OF DEFECTS MISTAKE PROOFING DETECTION OF CAUSES AND LEAD TO CORRECTIVE ACTION VISUAL CONTROL, SPC DETECTION OF DEFECTS INSPECTION Statistical process control BACK

6. VARIATION PRINCIPLES OF SPC   VARIATION IS INEVITABLE   VARIATION IS PREDICTABLE VARIATION IS MEASURABLE Statistical process control BACK

7. COMMON CAUSES SPL./ASSIGNABLE Plenty in nos. Few in nos. Variation is low Variation is high Part of the process Visitor to the process Constant variation Fluctuating variation Predictable Unpredictable Statistics applicable Statistics cannot apply Management controllable Operator controllable E.G pressure variation, environment variation E.G wrong setting, wrong master Reduction lead to improvement Elimination lead to maintenance Statistical process control CAUSES BACK

8.   STATISTICAL PROCESS CONTROL 10 % IS STATISTICS  90 % IS PRODUCT & PROCESS KNOWLEDGE Statistical process control BACK

9. SPC TOOLS HISTOGRAM -BELL SHAPE CONTROL CHART -NO OUT OF CONTROL NORMAL PLOT -STRAIGHT LINE   Statistical process control BACK

10. PROCESS CAPABILITY A PROCESS FREE FROM ASSIGNABLE CAUSES (PREDICTABLE PROCESS) PROCESS CAPABILITY IS A MEASURE OF INHERENT VARIATION   ( MANAGEMENT CONTROLLABLE) Statistical process control BACK

11. CAPABILITY INDICES Cp = POTENTIAL PROCESS CAPABILITY INDEX Cpk = POTENTIAL PROCESS CAPABILITY INDEX OR Where, LSL USL   Statistical process control BACK

12. CONTROL CHARTS OBJECTIVES OF CONTROL CHART TO DETECT SPECIAL/ASSIGNABLE CAUSES TO MAINTAIN THE ACHIEVED PROCESS CAPABILITY TO IDENTIFY THE OPPORTUNITY FOR IMPROVEMENT Statistical process control BACK

13. ADVANTAGES Reduces waste Lead to a reduction in the time required to produce the product or service from end to end due to a diminished likelihood that the final product will have to be reworked, identify bottlenecks, wait times, and other sources of delays within the process. A distinct advantage over other quality methods, such as inspection - its emphasis on early detection and prevention of problems Cost reduction Customer satisfaction Statistical process control BACK

14. LIMITATIONS SPC is applied to reduce or eliminate process waste. This in turn, eliminates the need for the process step of post manufacture inspection. The success of SPC relies not only on the skill with which it is applied, but also on how suitable or amenable the process is to SPC. In some cases, it may be difficult to judge when the application of SPC is appropriate. Statistical process control BACK

15. APPLICATIONS In Automotive Industry it is used to reduce waste & improve in production processes. Also in New product development of the part it is used to validate the processes. Healthcare & Pharmaceutical Industry to Monitor the Quality of Medicine & treatments. Software Engineering Processes in the Capability Maturity Model (CMM). The level 4&5 of the Capability Maturity Model Integration use this concepts. It is using in Machine setup to study the Machine Capability. In food industry, to monitor the quality of product. Statistical process control BACK

16. CONCLUSION Statistical process control (SPC) is a method of quality control which uses statistical methods . SPC is applied in order to monitor and control a process. Monitoring and controlling the process ensures that it operates at its full potential. At its full potential, the process can make as much conforming product as possible with a minimum (if not an elimination) of waste (rework or scrap ). SPC can be applied to any process where the "conforming product" (product meeting specifications) output can be measured. Key tools used in SPC include control charts; a focus on continuous improvement; and the design of experiments . Statistical process control BACK

17. REFERENCES www.wikipedia.com REFERENCE MANUAL _SPC_2nd_Edition of AIAG, Edition 2005 Nelson, Loyd S. (1985), "Interpreting Shewhart X Control Charts", Journal of Quality Technology, 17:114-16. Steel, R. G. D. and J. H. Torrie (1980), Principles and Procedures of Statistics. New York: McGraw-Hill. Western Electric Company (1956), Statistical Quality Control Handbook, available from ATT Technologies, Commercial Sales Clerk, Select Code 700 444, P.O. Box 19901, Indianapolis, IN 46219, 1-800-432-6600. Statistical process control BACK

18. QUESTIONS Statistical process control BACK