Development of a novel feature based manufacturability assessment system for high-volume injection moulding tool inserts

El Kashouty, Menna and Rennie, Allan and Ghazy, Mootaz (2020) Development of a novel feature based manufacturability assessment system for high-volume injection moulding tool inserts. PhD thesis, Lancaster University.

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Abstract

Selective Laser Melting (SLM) is a versatile fabrication method that provides freedom in design complexity through the development of net or near-net shape metallic components within certain limitations such as dimensional accuracy and surface finish. The rapid development of metallic Additive Manufacturing (AM) technologies and their wide-ranging applications facilitate the unprecedented challenges faced by automotive industries for the production of injection moulding tool inserts in timescales greatly reduced from those experienced when manufacturing using more established and conventional processes. It is accepted that AM has limitations with regard to surface roughness requiring post processing of the parts produced. Global demand is striving for the production of injection moulding tool inserts in terms of higher quality. Previous research was applied to investigate the benefits of AM in the production of low-volume injection moulding tool inserts. Potentially, AM could reduce manufacturing lead-time resulting in reduced processing costs while promising high level of flexibility in design. For many years it has been established that companies approved the use of AM for the sole purpose of prototyping and product sampling. Due to lack of knowledge of AM technologies, it has never been fully incorporated as a reliable technique for producing high-volume injection moulding tool inserts for the automotive industry, due to implications of previous research on surface finish of AM components, limitations in material use, durability, and incapability of improving product accuracy. Previous research was established for the production of low-volume injection moulding tool inserts. However, there is still a gap in research regarding the capabilities of AM technologies for the production of high-volume injection moulding tool inserts. Moreover, applying each manufacturing process individually is constrained by some technical limitations, therefore, establishing a paradigm that evaluates the manufacturability benefits of AM and subtractive manufacturing in a feature-based system is potentially valuable. This research addresses the competencies associated with adopting SLM for fabricating injection moulding tool inserts for high-volume production, and how advantageous it can be for the automotive industry. In this work, the tool life of SLM-fabricated injection moulding tool inserts and the functional approval of their respective end-products is analysed. Five sets of tool inserts (ten core and cavity inserts) of different spare part automotive components were manufactured using subtractive and SLM techniques. The tool inserts were grouped into different studies that assessed mechanical properties, microstructure, and performance when used to create end-use components. One of the studies was established to prove the tool life of SLM-fabricated tool inserts through the production of 150,000 functional components. The tool inserts performance was monitored under actual operating conditions considering high-level demands. The quality of the components produced from the SLM tool inserts were tested for geometric and dimensional accuracy as well as functional approval through an industrial quality control procedure as an end-use product. Products are functionally approved and are established to be within the permissible design tolerances for their application and industrial sector requirements. The results obtained from the different studies concluded that SLM is a viable and competitive approach for the fabrication of injection moulding tool inserts. Hence, a systematic approach is developed as a feature-based manufacturability assessment system (FBMAS) for the automotive sector to assist users to evaluate manufacturability limitations of SLM and subtractive manufacturing techniques for the production of injection moulding tool inserts. The manufacturability assessment process is based on a set of predetermined design features and geometric requirements which must be identified. Six tool inserts were acquired for the validation process, comparing real-life decisions of the experienced engineers with the outcome of the feature-based system. As a result, the manufacturability assessment system was able to present possible feature base recommendations for the manufacturability of high–volume injection tool inserts.