Comparison between microfabrication technologies for metal tooling

Abstract

This paper is based on the information gathered within the Multi-Material Micro-Manufacture (4M) Network activities in the Processing of Metals Division (Task 7.2 ‘Tooling’) ( www.4m-net.org ). The aim of the task involves a systematic analysis of the partners' expertise in different microtechnologies for processing tooling inserts made of metal. The following technologies have been analysed: micromilling, micro-electrodischarge machining (EDM, including wire-EDM, sinking-EDM, and EDM-milling), laser micromachining, electroforming, and electrochemical milling (ECF) (an electrochemical machining innovative process proposed by HSG-IMAT). Considered tool-insert materials are nickel for electroforming, stainless steel for ECF, and tool steel (AISI H13) for all other processes. Typical features (ribs, channels, pins, and holes) required by micro-optics, microfluidics, and sensor and actuator applications have been selected to form the benchmark part and to carry out this analysis. The results provide a global comparison between the micromanufacturing processes mentioned earlier in terms of technical capabilities and cost effectiveness of different feature machinings. As a second result, the current limitations of these technologies concerning feature sizes, surface finish, aspect ratios, etc. have been identified. The main conclusion drawn is the absence of a consolidated technology to produce three-dimensional free-form shapes smaller than 100–200 μm to date.

A new process chain for producing bulk metallic glass replication masters with micro- and nano-scale features

“…These include laser processing parameters and applied machining strategies (Fleischer & Kotschenreuther, 2007;Lalev et al, 2009;Uriarte et al, 2006;B. Wu & Ozel, 2011).…”

Tools for ultrasonic hot embossing

“…With x-ray lithography the aspect ratio is not limited by tool fabrication but by the deepest groove in the tool which can be filled with molten polymer. The achievable lateral dimensions can be as small as several micro meters or even nano meters, and the roughness of sidewalls is on the order of 10 nm [72,[88][89][90][91][92]. Because of the high running expense of X-ray synchrotrons, UV light is preferred for lithography when no high aspect ratio is required.…”

Performance of nickel and bulk metallic glass as tool inserts for the microinjection molding of polymeric microfluidic devices

“…However, the micromilled trench features cannot be smaller than 50µm, with a geometric tolerance of ±10µm, which is limited by the 50µm diameter of the smallest micromilling tools. Tool wear, when machining hard materials, influences the achievable accuracy, roughness, and generation of burrs (Uriarte et al, 2006). Micro-die EDM (electrical discharge machining) sinking has the problem of uneven wear of micro and macro features on the electrode.…”