K. Tomari et al., IMPROVEMENT OF WELDLINE STRENGTH OF FIBER-REINFORCED POLYCARBONATE INJECTION-MOLDED ARTICLES USING SIMULTANEOUS COMPOSITE INJECTION-MOLDING, Advances in polymer technology, 14(1), 1995, pp. 25-34
Fiber reinforced thermoplastics (FRTP) injection molded articles have
many advantages. However, moldings with a complex geometry often encou
nter weldline problems. Mechanical properties of the injection molding
s are often reduced by weldlines, because the fibers at weldline regio
ns orient perpendicularly to the flow directions. We have reported tha
t weldline strength is improved by ''back-flow'' during the holding st
age. In this article, we have attempted to adapt the SCI (Simultaneous
Composite Injection) molding method to improve weld strength of FRTP
injection moldings. The back-flow is expected to occur when there is a
difference of holding pressure between two cylinders of the SCI moldi
ng machine. The effect of pressure difference between two injection cy
linders on the back-flow phenomena is discussed for fiber reinforced p
olycarbonate. It is clear that the strength reduction by the weldline
can be suppressed down to negligibly small levels in SCI molding. (C)
1995 John Wiley and Sons, Inc.