ABSTRACT

Quality control (QC) is a procedure or set of procedures intended to ensure that a manufactured product adheres to a dened set of quality criteria or meets the requirements of the customer. It involves sampling inspection of the product during its manufacture by means of a planned system of patrol inspection of the production process where a xed number of parts are examined by the inspector at each site visit. The sample size varies from 2 to 10 in each case of quality control by variables. The sampling inspection results are plotted on the quality control chart that is kept adjacent to the machine performing the manufacturing operation to be controlled. The control chart provides a visual judgment for signicant deviations from standard quality. By taking appropriate action as indicated by the control chart, any tendencies for defective part production can be corrected before they are produced.