Colloquia

Samenvatting

In this research a redesign study is performed on the Rz Limiter. The Rz Limiter is part of a lithography machine for a semicon customer of VDL. This part is currently manufactured by VDL ETG Almelo, from a single block of titanium, by multiple milling stages including expensive gundrilling for only weight reduction. The primary goal of this redesign study is to reduce the manufacturing cost of the Rz Limiter, besides optimizing the design to achieve technical requirements that are currently not met. Examples of failed requirements in the current design are the maximum mass and minimum first natural frequency. Additionally, a wish for a backward compatible design was made by the semicon customer. The starting point for this research is to evaluate the benefits and drawbacks of applying a new metal/composite hybrid structure material. This results in an alternative manufacturing technique, which influences the new design.First steps in this research are an analysis of the current design to find the requirements and a literature review to evaluate applicable materials and find suitable manufacturing methods. Secondly, concepts were generated and selected with respect to the composed requirements in an iterative design process in collaboration with VDL Fibertech Industries. The design was modified first for Design for Manufacturing (DfM) and secondly optimized in a FEMstudy on the defined load cases. Lastly, physical prototypes were manufactured at VDL Fibertech Industries and dynamically tested for validation. In this research an Aluminium (Al) with Carbon Fiber Reinforced Plastic (CFRP) material combination was selected. Aluminium was selected for it's low price compared to titanium and low density and CFRP was chosen for it's excellent specific strength and stiffness. The selected manufacturing method is Resin Transfer Moulding (RTM) and post-processing by milling only in aluminium. By prototyping it was successfully demonstrated that the new Al/CFRP design can indeed be manufactured without considerable drawbacks. In this redesign study it is shown that a potential cost reduction of up to 70% could be achieved. Furthermore, the weight of Rz Limiter can be reduced to meet the specifications of the semicon customer. However, it was shown that the minimum first natural frequency was not accomplished and the desire for backwards compatibility was not met. More research should be performed on the cause of the lower first natural frequency and how to mitigate these effects. The not met backwards compatibility results in a required redesign of the assembled components on the Rz Limiter.