OM300 Study Guide 22

The objective of a process control system is to provide a statistical signal when assignable causes of variation are present “ if you can’t describe and measure it the you can’t control or improve it.” SPC a process used to monitor standards by taking measurements and corrective action as a product or service is being produced. Control chart a graphical presentation of process data over time. A process is said to be orperating in SC when only source of variation is common(natural) causes. The process must first be brought in statistical control by dectecting and elimination special(assignable) causes of variation. The objective of Process Control Sysytem is to provide a statistical signal when assignable causes of variation are present. Natural variation variability that affects every production process to some degree and is to be expected also known as common cause. Control charts for the mean x or x-bar and the range R are used to monitor processes that have variables (continuous dimensions). X-chart tells us whether changes have occurred in the central tendency(the mean) of a process. The R-chart values indicate that a gain or loss in dispersion has occurred. The theoretical foundation for x-charts is the central limit theorem which states that regardless of the distribution of the population of all parts or services, the distribution of x’s tends to follow a normal curve as the number of samples increases. 95.45 % +/- 2 std dev. 99.73% +/- 3 std dev. Attributes are typically classified as defective or nondefective. 2 attribute charts p-chart measure the percent defective in a sample and c-chart count the number of defects in a sample. Acceptance sampling method of measuring random samples of lots or batches of products against predetermined standards.
The objective of supply chain management is to coordinate activities within the supply chain to maximize the supply chain’s competitive advantage and benefits to the ultimate consumer. All supply chain