Bestimmung des Schwindungsverhaltens von spritzgegossenen, glasfaserverstärkten Kunststoffen

Translated title of the contribution: Determination of shrinkage behavior of injection molded glass fiber reinforced polymers

Tabea Zirnig

Research output: ThesisMaster's Thesis


The shrinkage of polymers is hardly predictable due to various influences. However, a precise prediction is essential to minimize the revision cycles of newly developed molds and improve the overall quality of products made by injection molding. Hence, resources such as materials, energy, time, and cost can be saved. In this thesis, an extended comparison of shrinkage values generated by simulation and measurements of injection molded parts is performed. In this thesis, three different grades of glass fiber-reinforced polyamides were investigated. For evaluation, parts were manufactured by injection molding, and the processing shrinkage as well as the total shrinkage were measured using a coordinate measuring device. The tests were carried out at five different pressure levels and two wall thicknesses. The data was evaluated in flow direction and perpendicular to the flow direction as well as for thickness. The simulations were done by using the software Autodesk Moldflow® Insight 2021.1 (AMI) using a 3D-model and a midplane model. The switch-over point and cavity pressure from the manufacturing process of the parts were used to imitate the exact process conditions in the simulation. Shrinkage values gained in the practical part were then compared with the results from the simulation and the differences are discussed in this thesis. It was found that the thicker parts correlate better with the practical values but only in the flow direction. Perpendicular to the flow direction as well as the thinner parts show a higher deviation to the practical results. Further, a deviation between the different simulation models was observed. As a second part of the thesis, a database of shrinkage values was created. The aim of this database is to estimate shrinkage values for new products based on existing, similar parts and polymers. This database should provide the designers with a tool, which allows them to make exact predictions for new projects, at low effort. Therefore, the parts can be filtered by their material and the article group. If matching products are available, the design details, process parameters as well as shrinkage values of the products can be viewed and applied for new comparable products.
Translated title of the contributionDetermination of shrinkage behavior of injection molded glass fiber reinforced polymers
Original languageGerman
Awarding Institution
  • Montanuniversität
  • Lucyshyn, Thomas, Supervisor (internal)
  • Schillfahrt, Christian, Supervisor (external)
Award date30 Jun 2023
Publication statusPublished - 2023

Bibliographical note

embargoed until 26-05-2028


  • shrinkage
  • injection molding
  • polyamide
  • glass fiber
  • moldflow
  • simulation
  • database

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