Abstract This paper presents the design of a plastic injection mould for producing warpage testing specimen and performing thermal analysis forthe mould to access on the effect of thermal residual stress in the mould. The technique, theory, methods as well as consideration neededin designing of plastic injection mould are presented. Design of mould was carried out using commercial computer aided design softwareUnigraphics, Version 13.0. The model for thermal residual stress analysis due to uneven cooling of the specimen was developed and solvedusing a commercial finite element analysis software called LUSAS Analyst, Version 13.5. The software provides contour plot of temperaturedistribution for the model and also temperature variation through the plastic injection molding cycle by plotting time response curves. Theresults show that shrinkage is likely to occur in the region near the cooling channels as compared to other regions. This uneven cooling effectat different regions of mould contributed to warpage.© 2005 Elsevier B.V. All rights reserved. 4039

Keywords:  Plastic Injection mould; Design; Thermal analysis
 1.  Introduction

Plastic  industry  is  one  of  the  world’s  fastest  growing
industries, ranked as one of the few billion-dollar industries.
Almost every product that is used in daily life involves the
usage of plastic and most of these products can be produced
by  plastic  injection  molding  method  [1].  Plastic  injection
molding process is well known as the manufacturing process
to create products with various shapes and complex geometry
at low cost [2].
The plastic injection molding process is a cyclic process.
There are four significant stages in the process. These stages
are filling, packing, cooling and ejection. The plastic injec-
tion molding process begins with feeding the resin and the
appropriate additives from the hopper to the heating/injection
system of the injection plastic injection molding machine [3].
This is the “filling stage” in which the mould cavity is filled
with hot polymer melt at injection temperature. After the cav-
ity is filled, in the “packing stage”, additional polymer melt is
packed into the cavity at a higher pressure to compensate the
expected shrinkage as the polymer solidifies. This is followed

∗ Corresponding author.
E-mail address: saihong@eng.upm.edu.my (S.H. Tang).

0924-0136/$ – see front matter © 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jmatprotec.2005.06.075

by “cooling stage” where the mould is cooled until the part is
sufficiently rigid to be ejected. The last step is the “ejection
stage” in which the mould is opened and the part is ejected,
after which the mould is closed again to begin the next cycle
[4].
The  design  and  manufacture  of  injection  molded  poly-
meric parts with desired properties is a costly process domi-
nated by empiricism, including the repeated modification of
actual tooling. Among the task of mould design, designing
the mould specific supplementary geometry, usually on the
core side, is quite complicated by the inclusion of projection
and depression [5].
In  order  to  design  a  mould,  many  important  designing
factors must be taken into consideration. These factors are
mould size, number of cavity, cavity layouts, runner systems,
gating systems, shrinkage and ejection system [6].
In  thermal  analysis  of  the  mould,  the  main  objective  is
to analyze the effect of thermal residual stress or molded-in 注塑模具的设计与热分析英文文献和翻译:http://www.751com.cn/fanyi/lunwen_513.html