Pioneering European Collaboration: First European Benchmark Study on Squeeze-Flow Tests of Carbon Fiber Sheet Moulding Compounds (C-SMC)

Sheet Molding Compound (SMC) is a flowable thermosetting compression molding compound reinforced with chopped fiber rovings, usually glass or carbon fiber. The semi-finished products are usually supplied in rolls. The material is processed by hot pressing in a parallel controlled hydraulic press. Stacks of cuttings are placed into a heated tooling and pressed into parts. The heat input initiates the curing reaction of the resin and produces the dimensional stability of the finished component. This efficient process enables the production of complex, lightweight, and durable components for applications such as automotive manufacturing, aerospace, and energy technologies. However, the significant variability in the flow behavior of these materials has made consistent product quality challenging.

Under the joint leadership of the University of Sheffield and Leibniz-Institut für Verbundwerkstoffe (IVW), a group of twelve European research institutions from seven countries has joined forces to better understand this variability and its causes. The Squeeze-Flow Test is used as a laboratory or technical-scale method to determine flow behavior and processing properties. This test is being carried out by the laboratories of all participating institutions in the form of a round-robin test.

In this setup, all laboratories initially perform the test on the same material, under standardized test conditions and with identical parameters, to determine intra-laboratory repeatability as well as inter-laboratory reproducibility. Subsequently, the systematic variation of fiber content, roving size and final part thickness will be used to examine their influence on the reproducibility of the test.

The study’s results are expected to contribute to better predictability of C-SMC compression molding outcomes and, in particular, to reduce the variability of process results. To ensure the large amount of data generated by each laboratory can be accurately assigned to their respective experiments, the laboratory information system PKDE, developed by IVW, is being employed. This also applies to data on temperature and humidity, which are recorded during the production, transport, storage, and testing of the material samples.

The consortium is supported by Polynt Composites Germany GmbH, one of the world’s leading manufacturers of SMC materials, which has generously provided nearly one ton of C-SMC for the study.

For more information about this study and opportunities for future research collaborations, please contact:

Dr. Miro Duhovic
Manager Process Simulation
Leibniz-Institut für Verbundwerkstoffe GmbH
Erwin-Schrödinger-Str. 58
67663 Kaiserslautern, Germany
Phone: +49 (0) 631/2017-363
E-Mail: miro.duhovic@leibniz-ivw.de

Dr. Ing. Andreas Gebhard
Research Director Digitalization
Manager Digitalized Process & Material Development
Leibniz-Institut für Verbundwerkstoffe GmbH
Erwin-Schrödinger-Str. 58
67663 Kaiserslautern, Germany
Phone: +49 (0) 631/2017-400
E-Mail:andreas.gebhard@leibniz-ivw.de

Dr. Connie Qian
Senior Lecturer in Composites
School of Mechanical, Aerospace and Civil Engineering
The University of Sheffield
Garden Street, S1 4BJ, Sheffield
E-Mail: c.qian@sheffield.ac.uk