P S i i l Process Control C l 26 August 2009 University Malaysia Perlis P li Presented by Dr Zaharah Wahid DRZ CONSULTANT 1 An Overview of Statistical Process Control (SPC) DRZ CONSULTANT 2 What is SPC Statistical : A universal language to describe and analyse the physical variability of a process. Process : The transformation of inputs including f f man‚ machinery‚ methods‚ materials‚ energy and information to attain a desired result result. Control : To make a process behave the
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Control Charts Control charts‚ also known as Shewhart charts are tools used to determine if a manufacturing or business process is in a state of statistical control. The control chart was invented by Walter A. Shewhart‚ (also known as the father of statistical quality control) while working for Bell Labs in the 1920s. The company’s engineers were seeking to improve the reliability of their telephony transmission systems. The engineers had realized the importance of reducing variation in a manufacturing
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Control Charts Control Charts are use to distinguishes between specialcause or common-cause of variation that is present in a process. There are two basic types of control charts:- Variables - Quantitative data (Measured) Attributes - Qualitative data (Counted) Variable Control Charts Use actual measurements for charting Types:- Average & Range charts Median & Range charts Average & Standard deviation charts Individual & Moving Range charts Run Charts Attribute
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Basic Tools for Process Improvement Module 10 CONTROL CHART CONTROL CHART 1 Basic Tools for Process Improvement What is a Control Chart? A control chart is a statistical tool used to distinguish between variation in a process resulting from common causes and variation resulting from special causes. It presents a graphic display of process stability or instability over time (Viewgraph 1). Every process has variation. Some variation may be the result of causes which are not normally
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5.4 5.4 5.5 3 5.9 5.6 5.2 5.2 5.6 4 5.5 5.5 5.9 5.3 5.3 5 5.5 5.4 5.8 5.3 5.2 6 5.4 6.0 5.9 5.3 5.6 7 5.6 5.2 5.3 5.6 5.9 8 5.8 5.2 5.3 5.6 5.5 Construct control charts for the shaft diameter for 3-sigma limit of confidence. Find whether the process is in control or not? Test with following data and find whether it meets specifications or not. Sample No. No. of Observation Sample No. No. of Observation 1 2 3 4 5 1 2 3 4 5
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Standard Operating Procedure for inline Q.A‚ using Statistical Process Control charts OBJECTIVE To remove or minimize‚ cost of poor quality. SCOPE This procedure is applicable for all kind of critical points for which variable charts are being made to know about the process stability. RESPONSIBILITY 1) Q.A. Manager Q.A. Manager is responsible for allotting the critical points in a particular product to in line Q.A.’s. 2) A.Q.M. A.Q.M. is responsible for carrying out
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Process control at Polaroid Basing your analysis on both quantitative and qualitative tools‚ what evidence is there that quality is getting better? Pod Weight control According to Pod Weight control chart in Appendix‚ the pod weight performance variability is within the control limit (between 2.774 - 2.835)‚ which means the process is in control. This indicates the quality is getting better since the Pod Weight defect rate is normal (Pod Weight measurement is a part of defect report issued
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Process Capability Assessment Control Charts for Individual Measurements Cumulative-Sum control charts Control Charts for Large Sample . . Statistical Process Control - Part II IE 330‚ Spring 2013‚ Instructor: Yu-Ching Lee March 14‚ 2013 1 / 127 Process Capability Assessment Control Charts for Individual Measurements Cumulative-Sum control charts Control Charts for Large Sample Use of the histogram Process Capability Indices Statistical Assignment of Tolerances Loss
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Statistical Process Control Statistical Monitoring of Processes to Detect Special Causes of Variation Lecture Outline • • • • • • • Basics of Statistical Process Control Control Charts Control Charts for Attributes Control Charts for Variables Control Chart Patterns SPC with Excel Process Capability Statistical QA Approaches Statistical process control (SPC) • Monitors production process to prevent poor quality Acceptance sampling • Inspects random sample of product
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Chaper 3. Statistical Process Control According to the book “Operations Management” by Russell and Taylor‚ Statistical Process Control (SPC) is defined as a statistical procedure that monitors the production process by detecting and preventing poor quality using various control charts and statistical tools. And the book also emphasizes on the importance of comprehensive training for employees in SPC to achieve its successful effect. (Taylor‚ B. & Rusell‚ R.‚ 2011) When working for Business Supporting
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