The miniaturization of machine components is perceived by many as a requirement for the future technological development of a broad spectrum of products. Miniature components can provide smaller footprints, lower power consumption and higher heat transfer, since their surface-to-volume ratio is very high. To create these components, micro-meso-scale fabrication using miniaturized mechanical material removal processes has a unique advantage in creating 3D components using a variety of engineering materials. The motivation for micro-mechanical cutting stems from the translation of the knowledge obtained from the macro-machining domain to the micro-domain. However, there are challenges and limitations to micro-machining, and simple scaling cannot be used to model the phenomena of micro-machining operations. This paper surveys the current efforts in mechanical micro-machining research and applications, especially for micro-milling operations, and suggests areas from macro-machining that should be examined and researched for application to the improvement of micro-machining processes.

Investigation of micro-cutting operations

Assembly of Microsystems

This paper summarizes our survey on the development of reconfigurable machines (RMs). The goals of this survey were to (i) clarify the needs and drivers to develop the RMs, (ii) define the academic and practical issues involved in the development of RMs, (iii) learn the state of the art of the RD while RMs are essential components to implement an RMS. RMs should be designed to meet a variety of task requirements via its reconfigurability. It has been found that few existing RMs can achieve this objective. The survey has concluded that the obstacles of the development of RMs include (i) the difficulties to identify and generalize design requirements since an RM is application-oriented and the design requirements have to be defined from an actual application; and in fact, some requirements are very difficult to be quantified; (ii) the lacking of efficient automated robot programming tools despite that the robots are essential components for most of the RMs; (iii) the lack of effective technologies that can be used to support system reconfigurations; (iv) no international organization that serves for standardizing the modular components for manufacturing and assembly processes; (v) the lack of the effort in implementing a heterogeneous system consisting of different types of RMs. The survey has suggested some future research works to overcome these obstacles.

Development of reconfigurable machines

A scanning electron microscope (SEM) provides real-time imaging with nanometer resolution and a large scanning area, which enables the development and integration of robotic nanomanipulation systems inside a vacuum chamber to realize simultaneous imaging and direct interactions with nanoscaled samples. Emerging techniques for nanorobotic manipulation during SEM imaging enable the characterization of nanomaterials and nanostructures and the prototyping/assembly of nanodevices. This paper presents a comprehensive survey of recent advances in nanorobotic manipulation, including the development of nanomanipulation platforms, tools, changeable toolboxes, sensing units, control strategies, electron beam-induced deposition approaches, automation techniques, and nanomanipulation-enabled applications and discoveries. The limitations of the existing technologies and prospects for new technologies are also discussed.

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Recent advances in nanorobotic manipulation inside scanning electron microscopes.

This paper investigates micro- and nano-scale (10 nm–2 μm) machining characteristics of a non-ferrous structural alloy, aluminum 7075-T6 (87 HRB) through a series of cutting experiments. Aluminum 7075-T6 is used in the die and mold making industry for creating prototype molds. The effects of cutting conditions on the machining forces, chip geometry, surface roughness, and derived parameters such as the specific cutting energy, shear angle and mean friction coefficient in orthogonal micro- and nano-scale cutting of Al 7075-T6 are presented and compared with trends observed in conventional macro-scale cutting. Explanations for the observed trends are given.

Experimental study of micro- and nano-scale cutting of aluminum 7075-T6

Micro-assembly differs from conventional assembly in terms of the size and characteristics of the objects involved. As a result the requirements relating to handling precision are so high that it is often very difficult to achieve them with manual operations. These extremely challenging requirements usually relate to environmental conditions and adjustable gripper tools, frequently equipped with a range of sensors. The extensive automation of micro assembly is therefore desirable for both cost and performance.

Equipment technology for flexible and automated micro-assembly

The assembly of hybrid micro systems is usually done by hand with the help of tweezers and optical microscopes. It is obvious, however, that only the automation will lead to an efficient and precise assembly process. This paper describes the design, the function and the application of mechanical grippers for automated micro assembly. These grippers are powered by piezo systems and are able to move their arms in sub-micrometer steps in order to grip micro parts very precisely. They can be equipped with sensors for the detection of gripping force and have been designed especially for use in a large-chamber scanning electron microscope (LC-SEM). Process observation is a main problem in all aspects of micro technology. The LC-SEM allows on-line process observation with a very high depth of focus and a large lateral resolution. It has a 2 m3 vacuum chamber in which complete assembly units can be installed. Furthermore the electron gun is freely movable, so that a sample can be observed from all directions. An additional advantage of this microscope is the clean production environment (vacuum).© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Assembly of hybrid microsystems in a large-chamber scanning electron microscope by use of mechanical grippers

Fertigungssysteme zur spanenden Herstellung von Mikrostrukturen

The fabrication of microstructured workpieces with conventional manufacturing methods, such as turning, milling, shaping or drilling--imposes high demands on the machine behavior and the tool properties. The requirements in terms of machine characteristics are currently met by only few machine tools. An ultra precision milling machine which permits microstructures to be manufactured with optical quality has been designed and built at the IPT in Aachen. Using natural diamond cutting tools, a broad range of materials like, for example non-ferrous metals or plastics, can be machined, producing real 3D-structures with a surface roughness of below 5 nm Ra. Only the diamond can be sharped to the required level of accuracy. Cutting edge sharpness and rounded are crucial to the manufacturing quality of the work piece. Minimum structure sizes in the submicron range and aspect ratios of more than hundred have been achieved by diamond matching at the IPT. Even small series or prototypes can be manufactured flexible and cost- effectively when mechanical cutting techniques are applied. Parts can be mass-produced cheaply when reproduction techniques, such as galvanic forming, injection molding or stamping are applied.

Manufacturing of microstructures using ultraprecision machine tools

The manufacturing of optics is an important field of technology and will serve key-markets in the future. The research activities of the Transregional Collaborative Research Center ”Process Chains for the Replication of Complex Optical Elements” SFB/TR4 of the Universities of Aachen, Bremen and Stillwater (USA) have the objective to lay the
scientific foundations for a deterministic and economic mass production of optical components with complex geometries, e.g. aspheric, non-rotational asymmetric or microstructured surfaces eventually superimposed on freeform geometries. The paper presents an approach for an integrated simulation and measurement interface for the analysis of manufacturing effects during the mold making as well as first results of its application on the basis of the manufacturing of mold inserts.

Manfred Weck

Papers

Equipment technology for flexible and automated micro-assembly

Assembly of hybrid microsystems in a large-chamber scanning electron microscope by use of mechanical grippers

Fertigungssysteme zur spanenden Herstellung von Mikrostrukturen

Manufacturing of microstructures using ultraprecision machine tools

Manufacturing of optical molds using an integrated simulation and measurement interface