Simulation analysis of injection molding for thick wall balance block of plastic products

Plastic injection molding can produce goods of complex shapes and high

precision．It is the principal means of the production of plastic products and has many

advantages，such as high production efficiency，low cost and prefect product quality．In

the process of injection molding，one of the key factors of product quality is

contraction affect．It not only reduces the size of products and the apparent precision

of quality, but also brings about structural deformation and internal defects．So

molding shrinkage has become an important problem to affect the field of plagued

injection molding and mold designing．In this paper，we probe the factors of the

injection products shrinkage，such as material properties，process conditions and the

structural characteristics of molding．SO we take the UMG ALLOY FA-840CA：UMG

ABS LTD as injection raw materials．and we take the thick—walled plastic balanced

block as the research object and take the Moldflow analysis as the research mean．

According to using the coordinate of the Flow+Wrap module of Moldflow with proe

to cope with the defects of contraction treatment in the thick-·walled three··

dimensional finite element mesh of Moldflow．we can get the shrinkage of the

balanced block thick-walled plastic parts and determine the size of cavity to certify

the dimensional accuracy requirements of plastic products by means of reasonably

choosing raw materials of injection molding，optimizing process parameters and

analysing the results to explore the method of solving shrinkage．The main

conclusions of the study are as follows：

1．According to the selected raw materials to analysis the balanced thick—walled

mold blocks．Firstly，find the best casting location by using the fusion grid．Secondly，

Propose improvement measures for the defects of the Moldflow to deal with

thick—walled plastic parts，changing the two-sided flow finite element mesh as

tetrahedral finite element mesh．And thus to analysis the balanced block process

parameters．The best process parameters for the cooling time is 20s and the pressure

time is 80s．

2．Use the results of the analysis to explore ways of solving shrinkage．And

solve the shrinkage of the thick-walled balanced block through the analysis．For the

thick．walled balanced block that its size iS 53．00mm×1 0．50mm×26．4 1 mm，it can be

divided into tetrahedral finite element mesh．It is not feasible to get shrinkage by using Moldflow,but we can know the size(ds)which iS compared contraction to warping

deformation utilizing the Flow+Wrap analysis module of Moldflow．Then use

three．dimensional modeling software proe and set various shrinkage to measure the

critical data of shrinkage．At last，comparing it with the critical data N and permission

error formula【M+ds】∈[N+6】，the result of shrinkage canbe draw：

S。=·0．00 1 1 2，Sr=-0．00000，Sz-0．00050．

3．The results show the shrinkage of the thick—walled balanced block iS

reasonable．It can ensure the two．hole pitch．axis precision iS士0．001 5mm and the hole

axis position accuracy is士0．0075mm．