Control charts

restraint Charts Control Charts atomic number 18 social occasion to distinguishes between specializes or common-ca subroutine 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 utilization actual measurements for charting Types- Average & Range charts Median & Range charts Average & Standard deflexion charts Individual & lamentable Range charts Run Charts Attribute Control Charts use pass/fall or go/no-go Judgment Type improvement.To determine the process capability. For decisions In attachment to product specifications. For current decisions in regard to recently produced items. Average & Range charts (0 and R) Guidelines for subgroup sizes (n)- As n increases the CLC become closer to central line. 2. As n increases the inspection cost per subgroup increases. 3. Distributions for averages of subgroups are nearly normal for n = 4 4. If n = 1 0 use the s -chart instead of R-chart . N = 5 commonly being used in industry 6.The lot of product that falls within any pair of values may be predicted with the highest degree of assurance. It permits the consumer to use the producers data The operator is performing satisfactorily from a quality viewpoint. PROCESS IN CONTROL (Natural ensample of variation) About 34% of the plotted points in an imaginary muckle between one standard deviation on both sides of the central line About 13. 5% of the plotted points in an imaginary band About 2. 5% of the plotted points in an imaginary band