Use of Statistical Charts and Process Capability for Improving Statistical Quality Control Techniques , an Experimental Study in Ur Company


This paper investigates the use of statistical control techniques such as (statistical control charts and process capability) in quality control of the electrical wires and cables which were produced in Ur Company (Cable factories) and in order to evaluate the performance of the manufacturing machines. Two types of manufacturing processes were selected namely (drawing and insulation) by testing diameter, max. tensile strength, elongation, and electricalresistance of wires, and testing of nominal thickness, strength, and elongation of insulation and sheathing of cables, for evaluating of quality control and process capability by using control charts namely (Average-Range) chart and process capability calculations andstatistical analysis based on histogram technique. The results showed that some of machines are unable to satisfy the specification tolerances due to wide differences in the resulted valuesof the statistical parameter. Therefore, it is important to carry out the total maintenance for these machines, and increase the quality control activities such as testing the raw materials by chemical analysis.