Media for Dimensional Stabilization of Rubber Compounds during Additive Manufacturing and Vulcanization.

Welf-Guntram Drossel,Erik Oelsch,Ralf Landgraf,Jörn Ihlemann,Marek Schmidt

doi:10.3390/ma14061337

Abstract

The current article proposes a concept for the additive manufacturing of rubber components using extrusion-based 3D printing, in which an additional medium is added to ensure the maintenance of shape within the elastomeric structure during the additive manufacturing process and in the subsequent vulcanization process. Specific requirements for the dimensional stabilization of the media were defined and suitable media were derived. Silicone rubber, molding sand, and plaster were examined in experimental vulcanization tests for their suitability as possible media with regard to shape retention. Selected rubber geometries made of NBR were embedded in these media to undergo the vulcanization process. The results show a significant influence of the media on the heating times. All media were able to ensure that the rubber geometries maintained their shape during vulcanization. Nevertheless, some side effects were found. The silicone rubber did not cure properly around the rubber sample. Therefore, it was difficult to remove it from the rubber after vulcanization. The molding sand caused an increased surface roughness on the rubber. Plaster changed the glossy surfaces at the beginning to a matte one after vulcanization and residuals were difficult to remove. However, all media can serve as stabilization media with specific changes.

Highlights

Additive manufacturing is a collective term for manufacturing processes in which a material is automatically applied layer by layer to a finished part or component
The current article proposes a concept for the additive manufacturing of rubber components using extrusion-based 3D printing, in which an additional medium is added to ensure the maintenance of shape within the elastomeric structure during the additive manufacturing process and in the subsequent vulcanization process
The rubber sample without media for dimensional stabilization (MDS) reached the temperature of 160 ◦C after 15 min and the target value of 170 ◦C ± 1 K after about 35 min

Summary

Introduction

Additive manufacturing is a collective term for manufacturing processes in which a material is automatically applied layer by layer to a finished part or component. Compared to traditional production processes for polymers, like injection molding, additive manufacturing processes have far fewer geometrical design restrictions and offer an enormous flexibility with regard to the individuality of components [1]. Depending on the application and product, liquid, powder, or solid materials can be used [2,3]. Elastic polymers such as thermoplastic elastomers can be processed using the FDM process [4]. Other examples are liquid silicones, which can be processed by Liquid Additive Manufacturing (LAM) or Drop on Demand process, see, e.g., [8,9]

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Results

Conclusion