The Influence of the Injection Molding Process in Structural Analysis

How many times have we heard that a one second reduction can affect millions of dollars? Injection molding process is one of the prominent methods of manufacturing plastics and short fiber reinforced composites. With plastic parts produced by the millions every year, any improvement in the manufacturing process that cuts time will multiply the benefits when looked at the annual production levels.

Plastic components and fiber reinforced composites are finding widespread applications in different industries like automotive, aerospace, consumer goods etc. Some of these parts are not just trim materials, but actual load bearing structural components in the system. Moldex3D from CoreTech Solutions in the Altair Partner Alliance (APA) offers engineers the tools to simulate the injection molding process, and make design changes that not only improve the product quality but also optimize the process parameters.

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A particular case study with Unilever (above) explains how the simulation of the manufacturing process made it possible to reduce the mold temperature and thus the cooling time by one second. With millions of parts manufactured every year, the ability to achieve these results while maintaining the same amount of resources used translates to huge savings. Moldex3D is valuable to mold designers as well. If given a desired part geometry, it can assist them in coming up with a cost effective design that meets form and function for the end product.

Shifting the focus from manufacturing to structural analysis, we notice that as a result of the injection molding process, especially with chopped fiber composites, the fibers are orientated based on the flow introducing a non-homogenous behavior of the material. The load bearing characteristics and stiffness of the parts are significantly affected by the fiber orientations and the residual stress state introduced in the manufacturing process. It is no longer sufficient to model these parts as isotropic materials in the structural analysis. Including results of a stamping simulation for crash analysis is a fairly established process, and there are benefits associated with it. In a similar manner, engineers that analyze reinforced plastics are becoming more and more aware of the importance of including injection molding simulation results to structural analysis models to better capture the anisotropic behavior. It is actually necessary to include manufacturing process conditions in order to capture the correct behavior of the part under loading conditions.

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There are multiple options available in the APA that help bridge the connection between manufacturing and structural analyses of short fiber composites. In this section, I want to mention briefly the mapping capabilities in Moldex3D. The fiber orientations, residual stresses and temperatures from the injection molding process can be mapped to a structural model within Moldex3D using the FEA Interface module. The use case is best explained by pointing to a customer case study that looks at modal frequencies of components showing a significant difference by considering the distributed mechanical properties rather than homogenous assumption. The injection molding simulation was performed in Moldex3D and the results mapped to OptiStruct to calculate the modal frequencies.

If you’re interested in mapping results from injection molding simulation in Moldex3D to structural analysis solver like OptiStruct, follow the basic steps mentioned in this document.

Questions or comments? Please email apatech@altair.com

Sridhar Ravikoti

Sridhar Ravikoti

Technical Director - Global Partner Programs at Altair
Sridhar Ravikoti is the Technical Director of Global Partner Programs at Altair. He has been with Altair since 2000, gaining experience in engineering product development and software program management. In his current role as a technical lead for the Altair Partner Alliance, Sridhar drives a synergetic relationship between Altair offering and its Partners. He holds a Bachelor’s degree from Osmania University in India, and a Master’s degree from the University of Nebraska-Lincoln, with a major in Mechanical Engineering and a minor degree in Applied Mechanics.
Sridhar Ravikoti
Sridhar Ravikoti

About Sridhar Ravikoti

Sridhar Ravikoti is the Technical Director of Global Partner Programs at Altair. He has been with Altair since 2000, gaining experience in engineering product development and software program management. In his current role as a technical lead for the Altair Partner Alliance, Sridhar drives a synergetic relationship between Altair offering and its Partners. He holds a Bachelor’s degree from Osmania University in India, and a Master’s degree from the University of Nebraska-Lincoln, with a major in Mechanical Engineering and a minor degree in Applied Mechanics.