Ehsan Soury - Nasr Bridge, P.O.Box ۱۴۱۱۵-۱۴۳, Faculty of Engineering, Tarbiat Modares University Tehran, Tehran, Iran
Amir Hossein Behravesh
Nathan Jafarian Jam
Alireza Adli

A problem that usually occurs in production of extruded parts of polymeric and in special wood-plastic composite (WPC) is flow instabilities at the extrusion die exit. In this paper influence of the important parameters of material and process on the surface quality (roughness) of extruded parts are investigated. The variable parameters are wood content, polymer melt flow index (MFI), screw speed, melt temperature, die diameter and finally length-to-diameter ratio of the die land. The Instabilities of die exit flow cause to defects on surface of profiles. The experiments specified that increasing die land length-to-diameter ratio (L/D), die temperature and wood content and decreasing screw speed and polymer MFI lead to improve the surface quality.

Wood-Plastic Composite, Extrusion, Instability, Surface Quality, Defect