Over the last few years additive manufacturing (AM) processes underwent a development from a niche process for rapid prototyping to a well-established manufacturing process for end-user parts. Opposed to conventional manufacturing processes like subtractive (milling, drilling) or formative (casting, forging) processes, where material is taken away or just formed into another shape, in additive manufacturing processes new material is added to the part during the production without the need for any tools or molds. Therefore AM-processes offer a high degree of part complexity and freedom of design combined with low costs for single parts and low volume production.
Most AM-processes for metal parts can produce components which can compete with conventionally manufactured parts in regard to mechanical properties like Young’s modulus or tensile strength. Parts made from polymers like thermoplastics however are inferior to conventionally manufactured parts in regard to mechanical properties. Therefore, the aim of this doctoral dissertation is the development, commissioning and parameter analysis of an AM-process for thermoplastics with superior mechanical properties.
This goal can be achieved by implementing continuous fiber reinforcements during the AM-process of an ARBURG freeformer by use of a fiber-feeding-module. In order to develop the aforementioned module, the current state of the art of additively manufactured fiber-reinforced-polymers (FRP) is evaluated and different assessment-criteria are defined. Based on those criteria and the boundary conditions given by the ARBURG freeformer and a demonstration-part from the formula student team KA-RaceIng the fiber-feeding-module is developed and commissioned.
Using an analysis of variances (ANOVA) approach, a study of dependence between different manufacturing parameters and mechanical values is conducted. The best Young’s modulus of 16.2 GPa is achieved with an fibre-volume-content (FVC) of 21.1 %. The best tensile strength of 168 MPa is achieved with an FVC of 9.7 %. With this, 94 % of the calculated Young’s modulus (FVC 21.1 %) and 56 % of the calculated tensile strength (FVC 9.7 %) were achieved. Processes from the state of the art achieved a maximum of 69 % (Young’s modulus) and 62 % (tensile strength).