Software Helps Predict Sink Marks in POM Parts

Resin manufacturer Polyplastics has developed a process applying CAE analysis to predict sink marks in parts molded from acetal, including the company’s Duracon POM material. A Polyplastics spokesperson told Plastics Technology that the CAE utilized includes a proprietary program it developed in conjunction with Autodesk’s Moldflow and SCSK’s AdventureCluster.

Polyplastics says this technology can predict the risk of sink marks before molds are fabricated, thereby shortening the development cycle for a new product by decreasing the number of prototypes required. Sink marks —which can arise due to uneven thickness distributions in a part and impact overall aesthetics — should be avoided in certain areas of a molded product due to dimensional accuracy requirements, sealing surface precision or design parameters.

Polyplastics says it has developed a new technology that combines flow and structural analysis to predict sink mark formation during resin curing by considering shrinkage, elastic modulus and pressure distribution. The company has completed experiments it says validate the program’s predictive accuracy. It is also testing the technology’s ability for predicting vacuum void and sink mark formation in various shapes and materials, while also considering the impact of fiber orientation, especially in anisotropic materials. The spokesperson says the development work is ongoing. The company offers consultations on sink mark prediction technology as part of its technical services, helping customers with product development in the initial design stage.