Investigation of the effects of various parameters on plastic pipe production

The effects of vacuum, haul-off speed and cooling water temperature on the outer diameterand the wall thickness of the plastic pipes, made from polypropylene random copolymer rawmaterial, were investigated using statistical process control techniques.The extruder speed, raw material, vacuum, cooling water temperature, haul-off speed, bothgiven and measured weights, outer diameter and wall thickness data were collected in adefined time period and then X-R control schemes were drawn and process capability analysiswere examined. The graphs for outer diameter and wall thickness versus process parameterswere drawn and the tendencies were determined.We found that it is easier to keep wall thickness under statistical control then outer diameterin plastic pipe extrusion. It was observed that the outer diameter has a lineer relationship withvacuum, haul-off speed and cooling water temperature, but the wall thickness has a inverserelationship with vacuum and haul-off speed.Keywords: Plastic pipe, extrusion, statistical process control.JURY:1. Prof. Dr. Mualla Öner (Danışman) Date: 02.01.20062. Prof. Dr. Ülker Beker Page: 1023. Prof. Dr. M. Ali Gürkaynak