| dc.description.abstract | Injection Molding Process is a closed cycle process involving 4 important factors
that influencing product quality such as: process setting parameter, plastic material
selection, product design and mold design. Ideally a plastic product is designed with
uniform wall thickness since the thickness variation brought about negative effect on
the final product. Those negative effects are warpage, sink mark or voids. Warpage
is a bending failure of product, void cannot be observed as unfilled or holes on the
cross section of the part, whereas sink mark is a deflected mark that can directly be
seen on the surface of the part. Those 3 failures are normally caused by material
accumulation and thermal rate differentiation. This research was a computerized
based simulation using Autodesk MoldFlow Plastic Insight software to predict the 3
failures and to optimize the product quality by Sink Mark Index reduction,
minimizing sink mark estimation and volumetric shrinkage due to extreem
thickness variation. The selected specimen was a brush handle, a real product that
can easily be found in the market. The errors of brush handle in fact was caused by
poor design and the only way to improve its quality is from process parameters point
of view. There are 5 possible factors in fixing the failures, each factor possessed 3
level of values, then according to the Taguchi approach of design experiment, there
must be 27 experiments to be done. After having 27 times experiments with
combination of level and factors, it can be summerized that by combining low
melting temperature, high injection pressure and high holding pressure, a sink mark
index of 2.642% and a volumetric shrinkage of 19.28% can be obtained, and those
were the minimum values representing the best results of product. The extension of
holding time did not give a significant influence on the target quality | en_US |
