Thermoplastic profile extrusion lines. Fabrication steps

In Europe, the overall market for profiles is booming. According to an AMI market study, PVC was the most widely used polymer in 2009, accounting for over 90% of the market. This profile market is dominated by production in Germany (47% of European production) and is driven by the continuous increase in demand for insulation in the building sector. According to the same study, profiles for building openings account for approximately 65% of the total thermoplastic profile market. According to an IC Market Forecast Windows study, the window profile market, following a decline in volume (in terms of the number of windows installed) due to the crisis between 2007 and 2010, is expected to grow by 1.5% annually between 2011 and 2014. The PVC window profile segment accounts for approximately 40% of the overall window profile market (all materials combined, i.e., wood, aluminum, etc.), with this proportion steadily increasing. Significant growth in this market is therefore expected in the coming years. The importance of these profiles necessitates a deeper understanding of the technical manufacturing steps. Their production line is technically very similar to tube extrusion lines, but the predominance of PVC processing requires the use of interpenetrating counter-rotating twin-screw extruders, and the complex shapes demanded necessitate specialized dies and calibrators. This article, following a review of the market’s significance and a description of the various profiles, aims to examine the different stages of profile production and introduce the statistical process control (SPC) tools necessary for process analysis and ensuring the required dimensional quality. Finally, the main defects observed, along with their possible causes and remedies, are described.