David Maximilian Marhöfer

Advancements on the simulation of the micro injection moulding process

Process simulations are applied in micro injection molding with the same purpose as in conventional injection molding: aiming at optimization and support of the design of mold, inserts, plastic products, and the process itself. Available software packages are however not well suited for micro injection molding, because they are developed for macro plastic parts and they are therefore limited in the capability of modeling the polymer flow in micro cavities properly. However, new opportunities for improved accuracy have opened up due to current developments of the simulation technology. Hence, new strategies and aspects for comprehensive simulation models which provide more precise results for micro injection molding are discussed. Modeling and meshing recommendations are presented, leading to a multi-scale mesh of all relevant units in the injection molding process. The implementation of the process boundary conditions is described, being followed by results illustrating their importance on the simulation output. Finally, the influence of the cooling simulation settings is analyzed.

The shrinkage behavior and surface topographical investigation for micro metal injection molding

Metal injection molding (MIM) is a near net shape manufacturing technology that can produce highly complex and dimensionally stable parts for high end engineering applications. Despite the recent growth and industrial interest, micro metal molding is yet to be the field of extensive research especially when it is compared with micro molding of thermoplastics. The current paper presents a thorough investigation on the process of metal injection molding where it systematically characterizes the effects of important process conditions on the shrinkage and surface quality of molded parts with micro features. Effects of geometrical factors like feature dimensions and distance from the gate on the replication quality are studied. The influence of process conditions on the achievable roughness for the final metal parts is discussed based on the experimental findings. The test geometry is characterized by 2½D surface structures containing thin ribs of different aspect ratios and thicknesses in the sub-mm dimensio...

A comparative study of metal and ceramic injection moulding for precision applications

DTU Orbit (10/12/2018) A comparative study of metal and ceramic injection moulding for precision applications Powder injection moulding (PIM) process is an attractive process as it combines the possibilities of net-shape and largescale production with wide range of material varieties. This article presents a comparative study of two branches of PIM processes with the focus on precision application. The two branches of PIM metal injection moulding (MIM) and ceramic injection moulding (CIM) have been developed in parallel. Both processes are in a stage now where they can offer exciting possibilities for mass production of extremely precise and complex net shape products. For some applications, PIM process presents a dilemma for choosing between MIM and CIMas both the material classes can offer specific advantages and the process steps are identical. So a comparative study about the process capabilities between CIM and MIM will be useful for thorough understanding of the processes and to select the right material and process for the right application.With this motivation, the current paper systematically characterizes the PIM and CIM process and presents the process capabilities in terms of part shrinkage, surface replication, tolerance capability and morphological fidelity.

Gate Design in Injection Molding of Microfluidic Components Using Process Simulations

Just as in conventional injection molding of plastics, process simulations are an effective and interesting tool in the area of micro-injection molding. They can be applied in order to optimize and assist the design of the microplastic part, the mold, and the actual process. Available simulation software is however actually made for macroscopic injection molding. By means of the correct implementation and careful modeling strategy though, it can also be applied to microplastic parts, as it is shown in the present work. Process simulations were applied to two microfluidic devices (a microfluidic distributor and a mixer). The paper describes how the two devices were meshed in the simulations software to obtain a proper simulation model and where the challenges arose. One of the main goals of the simulations was the investigation of the filling of the parts. Great emphasis was also on the optimization of selected gate designs for both plastic parts. Subsequently, the simulation results were used to answer the question which gate design was the most appropriate with regard to the process window, polymer flow, and part quality. This finally led to an optimization of the design and the realization of this design in practice as actual steel mold. Additionally, the simulation results were critically discussed and possible improvements and limitations of the gained results and the deployed software were described. Ultimately, the simulation results were validated by cross-checking the flow front behavior of the polymer flow predicted by the simulation with the actual flow front at different time steps. These were realized by molding short shots with the realized molds and were compared to the simulations at the global, i.e., part level and at the local, i.e. feature level.

Experimental Investigation of Comparative Process Capabilities of Metal and Ceramic Injection Molding for Precision Applications

The purpose of this paper is to make a comparative study on the process capabilities of the two branches of the powder injection moulding (PIM) processmetal injection moulding (MIM) and ceramic injection moulding (CIM), for high-end precision applications. The state-of-the-art literature does not make a clear comparative picture of the process capabilities of MIM and CIM. The current paper systematically characterizes the MIM and CIM processes and presents the process capabilities in terms of part shrinkage, surface replication, tolerance capability and morphological fidelity. The results and discussion presented in the paper will be useful for thorough understanding of the MIM and CIM processes and to select the right material and process for the right application or even to combine metal and ceramic materials by moulding to produce metal-ceramic hybrid components.