PhD Defence at DTU Mechanical Engineering

PhD Defence 14th April: "Design and Manufacture of Micro Products Using Concurrent Engineering"

Monday 04 Apr 16

David Maximilian Marhöfer from DTU Mechanical Engineering defends his PhD, "Design and Manufacture of Micro Products Using Concurrent Engineering", Thursday 14th April from 13:00 to 15:00. The defence takes place in Auditorium 36, Building 306.


The matter of this thesis is the design and manufacture of micro parts made by micro and powder injection molding. Multiple aspects of the design process towards the final micro component were investigated with the aim of establishing the optimal micro part and mold design in a holistic design approach. The focus was on simulation-aided design for manufacture and assembly.

First, the state-of-the-art of injection molding technology and of process simulations in the area of micro injection molding is presented in the theoretical part of this thesis as foundation for the following issues. Furthermore, the mathematical background of injection molding simulations is outlined.

In correspondence to the holistic design procedure, the experimental part of the thesis commences with the discussion of the conducted comprehensive material characterization of several feedstocks. The characterization contained mainly the thermal and rheolocial material properties and led to a material model enabling process simulations of powder injection molding. Subsequently, the process simulations of polymer micro injection molding were evaluated regarding the comprehensiveness of the model and the experimental validation.

The simulation-assisted approach was applied in the design for manufacture and assembly of a microfluidic plastic part and its feed system in the early product development phase and in absence of the mold. In two design iterations based on the design of experiment approach, the most suitable material and gate concept were selected, and the part quality was successfully optimized, so that the part complied with the requirement of a maximum flatness of 10 μm by implementing a 900 μm wide pin gate.

Process simulations were also utilized for the design optimization of the actual component and the mold of a second microfluidic device. The concurrent investigations covered the whole development from the first concept to the manufactured mold.

Hence, the material selection and testing, the iterative simulation-aided optimization of the gating conception, and the implementation of the mold are presented. The examination on the gate design resulted in the realization of a film gate with 560 μm thickness minimizing the risk of degradation due to excessive shear and the best packing performance. The molded parts of the two aforementioned micro components were moreover employed in additional simulation validations.