Thursday 19 May 2022

6 Major Benefits of Injection Moulding Simulation in Polymer Part Design and Material Selection

Hello and welcome to a new blog post. Today we have a closer look at how injection molding simulations support us in part design, polymer material selection and processing.

1. Injection point and gate placement

Finding the optimal injection point and gating is key to fulfill certain aesthetics or warpage requirements. Also, it helps to prevent flow line situations and as a consequence lower mechanical performance of your part. Nowadays most polymer injection molding simulations have gate placement tools integrated which can recommend you the optimal injection point. 

2. Placement and balancing of runners

Bringing the molten polymers towards the cavity, runners (thin channels) are needed. Aim is to ensure an even filling of your cavity. Runner analysis is hand in hand with the gating analysis from the previous point and most simulation software have a runner balance tool too. 

3. Warpage and shrinkage situation 

Analyzing the shrinkage and warpage situation is in particular needed when you use fiber-reinforced polymers which have an effect on the shrinkage and warpage of your part. Filling simulation can use the information of the velocity vectors to predict fiber behavior in the final part. And over this route, calculate the effect on shrinkage and warpage. 

4. Packing situation 

Analyzing the packing situation allows you to set the packing pressure and time for your part. There are several factors such as the material and mould shape which are influencing the packing. Packing analysis covers the prediction of the gate freeze time, clamping force needed in this phase, and predict areas where high volumetric shrinkage may appear. 

5. Cooling - mold 

There are injection moulding simulation tools which allow a design and optimization of the cooling channel layout of your moving and fixed moulding half. However, most tools simulate a uniform mould cooling at a set temperature.

6. Processing - identify critical shear rates

In case you work with polymers which are sensitive to mechanical stresses like shear rates then it is worth to have a plan of action how to locate critical areas and solve them by using simulation or in a simple way with analytic methods.

In the video I made you can see the perforated plate in the version of side gating and central gating. This applied method of shear rate tracer release is possible in the virtual molding package Sigmasoft.

In the following are the four steps of my procedure I use in the post-processing after I have done a process simulation:

1) Watch the shear rate contour plot to get the "big picture"

2) Activate the shear rate tracer

3) Analyze the release places and where the sheared material will end up in the part (to predict if there will be a decrease in the mechanical properties of the part)

4) Make geometry changes or process changes (melt temperature; inlet velocity profile)

The shear rate tracer method helps you to locate the punctual critical areas. So far, those are the advantages of such an approach. Another aspect is that the allover simulation will take more time and more memory as well as more working space.

In detail you can read here about my shear rate analysis. 

What are some of the most used injection moulding simulations?

There are several suppliers and often used are Autodesk Moldflow, SIGMASOFT Virtual Molding, Moldex3D, Vero VISI Flow, Simcon CadMould, and Solidworks Plastics.

Thanks for reading and till next time!




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