A Study of Extrudate Swell Behavior in Tread Die

Abstract

The purpose of this research is to study extrudate swell behavior in tread die of rubber
compound. Single-factor ANOVA was designed for the experiment. There were three load levels
in the extrusion; 1.720, 1.735 and 1.750 kg/m According to the experiment, rubber compound
melt extrusion by single screw extruder used profile die for tire of sport utility vehicle (SUV)
225/65R17 102 H. The result was load in high level tended to increase nonlinearly die swell ratio
of tread and caused width and thickness of tread to be bigger. Also, width of tread increased
higher, 9 as much average thickness per higher die swell ratio. This relationship indicated that
if tread width could be controlled, the tread thickness or shape could also be controlled. The
manufacturer can use the suitable load 1.720 kg/m for tread quality control within specification
(weight is 964±24 g/500 mm and width is 214±2 mm), not need to adapt extruder conditions or
die modifying. Results from this study led to a higher process capability ratio in tread extrusion
process for tread weight from 0.76 to 1.61 and tread width from 0.80 to 1.40.