Process capability analysis in the manufacturing of PET bottles

Modern process control is based on the use of statistical methods to improve and ensure quality, and thus reduce the process cost due to waste and rejects. The paper deals with the process capability analysis in the manufacturing of poly(ethylene-terephthalate) bottles for packaging of table oil. PET bottles are manufactured by the procedure of injection stretch blow moulding. The preforms made by injection moulding are biaxially extruded in the blow mould, with blow parameters affecting the mechanical properties, the barrier properties and the transparency of the manufactured bottle. The performance of blow moulding machine was monitored by measuring the volumes of blown bottles. Based on the collected data, the capability analysis of the blow moulding process was conducted.