Investigation of additively manufactured lost cores for the production of hollow bodies by silicone casting

Abstract

Lost cores have been used for many years in the industry for fibre composites, injection molded and die-cast components. The lost cores are generally used to support the later component material or temporarily fill cavities during the respective manufacturing process. Afterwards the dissolution process begins and the core material is removed from the manufactured part. The core is removed, for example, on contact with water, through increased temperature or mechanically. This process creates a cavity inside of the component that could not be produced in any other way using direct manufacturing processes.

In industrial applications, this process is used for large-area components where the opening size of the component and thus the contact surface of the solvent with the core plays a minor role. The aim of this publication is to investigate various additively manufactured lost cores that are used to manufacture smaller silicone cast components. The aim is to keep the opening in the silicone casting component as small as possible so that it can be closed after the dissolution process of the additively manufactured part, thus creating a completely closed cavity in the component. This can otherwise only be achieved using a double-shell concept.

To achieve the goal of making the opening as small as possible, various methods for dissolving the additively manufactured lost core are being investigated. These include dissolving in liquids, melting under the influence of temperature and mechanical removal of the core. All core materials are manufactured using different additive manufacturing processes. This publication concludes with an outlook on future tasks and its industrial relevance.