Manufacturability of Wood Plastic Composite Sheets on the Basis of the Post-Processing Cooling Curve

Abstract

Extruded wood-plastic composites (WPCs) are increasingly regarded as promising materials for future manufacturing industries. It is necessary to select and tune the post-processing methods to be able to utilize these materials fully. In this development, temperature-related material properties and the cooling rate are important indicators. This paper presents the results of natural cooling in a factory environment fit into a cooling curve function with temperature zones for forming, cutting, and packaging overlaid using a WPC material. This information is then used in the evaluation of manufacturability and productivity in terms of cost effectiveness and technical quality by comparing the curve to actual production time data derived from a prototype post-process forming line. Based on this information, speed limits for extrusion are presented. This paper also briefly analyzes techniques for controlling material cooling to counter the heat loss before post-processing.

Method for Limiting Waste in Wood Plastic Composite Post-Production by Means of Press Unit Control Parameters Utilizing Temperature-Related Dimensional Changes

“…Manufacturers often anneal the WPC profiles to reduce the final shrinkage of products (Klyosov 2007). On the basis of the present study, annealing the composite material before the reheating cycles could be suggested to minimize the residual shrinking effect.…”

“…The material recipe, density, extrusion speed, and downstream pooling have a direct effect on the shrinkage rate of a WPC (Klyosov 2007). However, the used measurement method and logic control can be utilized with other thermoplastic fiber composite materials.…”

“…Currently, the WPC products available on the market are mostly limited to extruded profiles (Klyosov 2007). However, there is increasing demand for more complex product shapes and geometries, which need post-extrusion processing after the material fabrication stage.…”

“…Previous studies have shown that WPCs can be post-formed, and natural cooling does not set strict limitations for the manufacturing process (Matthews et al 2015;Toghyani et al 2016). It has been demonstrated that thermoplastic WPCs can be recycled by a re-extrusion process (Sarabi et al 2014), and also that the properties of WPCs can improve during material re-processing (Sarabi et al 2012).…”

“…Radford and Rennick (2000) state that there are two major mechanisms that cause warpage: thermoelastic (thermal expansion) and non-thermoelastic (curing). Shrinkage and thermal expansion are known phenomena in WPCs that have been studied in outdoor surface decking (Klyosov 2007). While thermal expansion is reversible, the shrinkage effect caused by curing is not.…”