4M Knowledge base - papers

G. Tosello(a), B. Fillon(b), S. Azcarate(c), A. Schoth(d), L. Mattsson(e), C. Griffiths(f), L. Staemmler(g), P.J. Bolt(h)
a: Technical University of Denmark (DTU), Department of Manufacturing Engineering and Management (IPL), 2800 Kgs. Lyngby, Denmark
b: French Atomic Energy Commission (CEA), Laboratory of Innovation for New Energy Technologies and Nanomaterials (LITEN), 38054 Grenoble, France
c: Tekniker Technological Center, 20600 Eibar, Spain
d: University of Freiburg, Institute of Microsystem Technology (IMTEK), 79110 Freiburg, Germany
e: School of Industrial Technology and Management (KTH), Department of Production Engineering, 100 44 Stockholm, Sweden
f: Cardiff University, Manufacturing Engineering Center (MEC), Cardiff CF 24 3AA, UK
g: Hahn-Schickard-Gesellschaft, Institute for Micro Assembly Technology (HSG-IMAT), 70174 Stuttgart, Germany
h: TNO Science & Industry, 5600 HE Eindhoven, The Nederlands

Abstract

This paper is based on the Division 4 “Processing of Polymers” activities within the 4M NoE “Multi-Material Micro Manufacturing”. To overpass limitations of the current existing micro tooling capabilities, a new generation of micro hybrid tooling technologies for micro replication was developed. A metrological approach was applied to standardize the employed tooling processes (μ-milling, μ-EDM, laser μ-machining, electrochemical μ-milling). The micro tools were then tested with different polymers. The paper provides a comparison of these technologies concerning obtainable feature sizes, surface finishing, and aspect ratios of both micro tools and micro moulded parts.

W. Michaeli, T. Kamps
Institute of Plastics Processing at RWTH Aachen University, 52056 Aachen, Germany
A De Grave, T. Eriksson, H.N. Hansen
Department of Manufacturing Engineering and Management, Technical University of Denmark, 2800 Kgs., Lyngby, Denmark

Abstract

Demoulding micro structured surfaces and micro parts is an important issue in replication of micro technology based components. In this paper a state of the art on ways to improve demoulding of microstructured parts both in polymer moudling and metal injection moulding is presented. The approach is described and simulation methods are shown in relation to previously existing studies. The approach chosen is the investigation of the influence of the demoulding angle on the demouldability of polymer mouldings. The design is based on a number of micro sized cones with different slope angle placed on a flat metal surface. A mould design is proposed and simulated. The design is based on a number of micro sized cones with different slope angle placed on a flat metal surface. A method for characterization of the mould using Laser Scanning Confocal Microscopy (LSCM) and Atomic Force Microscopy (AFM) to verify the slope angle and the straightness quality of the slope is discussed. Initial mould filling simulations using a 2½ D mesh show that a real 3D simulation were performed.

Micro products made of thermosetting polymers enable innovative applications since thermoplastics do not always yield the desired properties: thermosetting moulding grades offer advantages in thermal durability and chemical resistance in comparison to thermoplastic resins. Processing smallest quantities of polymeric material for applications in micro system technology require high process accuracies, e.g. in the volume of plasticised material and injection dynamics. Alternative machine concepts especially designed for micro injection moulding meet these requirements by means of special constructive setups mostly by using a plunger for injection. An appropriate micro injection moulding machine prototype is available at IKV Aachen. A new design of the plasticising and injection unit specially designed for thermosetting moulding materials is presented in this paper.

G. Tosello(a), A. Gava(b), H. N. Hansen(a), G. Lucchetta(b), M. Guarise(a)
a: Department of Manufacturing Engineering and Management (IPL), Technical University of Denmark (DTU), Produktionstorvet, Building 427S, Kgs. Lyngby, DK-2800, Denmark
b: Department of Innovation in Mechanics and Management, University of Padua, Via Venezia 1, Padova, 35131, Italy

Abstract

Micro injection moulding is one of the most used processes for the mass replication of polymer-based micro components. To enable its mass fabrication capability, an optimization of the process and a full understanding of the filling of the micro cavity are fundamental requirements to be fulfilled. In this paper, a novel approach based on the use of weld lines as flow markers able to trace the development of the flow front during the filling is proposed. The effects on the filling stage of process parameters such as temperature of the melt, temperature of the mould, injection speed, and packing pressure have been investigated. An optical coordinate measuring machine has been employed for the scope. The micro cavity, which presents micro features ranging from 600 μm down to 150 μm, has been manufactured by micro electrode discharge machining. A commercially available polystyrene grade polymer has been moulded using a high-speed injection moulding machine. Results show that the temperature of the mould and the injection speed are the most influencing process parameters during the injection moulding of a micro component.

V. Piotter, G. Finnah, K. Plewa, R. Ruprecht, J. Hausselt
Forschungszentrum Karlsruhe, Institute for Materials Research III, P.O. Box 3640, 76021 Karlsruhe, Germany

Abstract

In recent years Microsystems Technology products made by thermoplastic injection moulding have steadily entered the worldwide market, and this trend will certainly continue in the next years. On the other hand, there is still a lack of methods for the processing of materials other than thermoplastics, and there is also the necessity to reduce assembly expenditures.

To improve the materials variety the so-called Micro Powder Injection Moulding (MicroPIM) process facilitates a medium- and large-scale fabrication technology for metal and ceramic micro components. Examples are micro gear wheels manufactured on a specially equipped micro injection moulding machine. Minimum dimensions achieved so far are 50μm of part thickness or minimum structural details of less than 10μm. Densities up to 99% of the theoretical values were achieved depending on the particular powder applied. Typical materials are oxide ceramics, conductive ceramics, alloyed steels, or hard metals.

A remarkable new approach is the realization of material combinations like conductive/non-conductive or magnetic/non-magnetic within one singular part by two-component MicroPIM. The main technical challenges are the process parameters which have to be suitable for both materials and the question of adhesion in micro areas. As merging and shaping takes place simultaneously, expensive mounting steps can be omitted.

G. Tosello (a), A. Schoth (b), H.N. Hansen (a)

(a) Technical University of Denmark (DTU), Department of Mechanical Engineering, Produktionstorvet, Building 427S, DK-2800 Kgs. Lyngby, Denmark
(b) Laboratory for Process Technology, Department of Microsystems Engineering (IMTEK), University of Freiburg, George-Koehler-Allee 103,79110 Freiburg, Germany

Abstract

In polymer micro manufacturing technology, software simulation tools adapted from conventional injection moulding can provide useful assistance for the optimization of moulding tools, mould inserts, micro component design, and process parameters. Conventional implementation methods of simulation are not suitable for micro injection (μIM) application and are limiting the possibility to extend the use of existing packages for the modelling and the simulation of polymer micro parts. Different strategies optimized for the set-up the simulation of a miniaturized part with micro features are presented. Model design and mesh issues are discussed, as well as dynamic implementation of the flow constrains for the creation of an effective interface between the machine and the polymer flow in the simulation software. The results of the different methods are evaluated by means of a quantitative study which compares the simulated results and the actual micro injection moulding experiments.