Trends in small parts assembly automation

Citation

Karjalainen, I. (2007), "Trends in small parts assembly automation", Assembly Automation, Vol. 27 No. 2. https://doi.org/10.1108/aa.2007.03327baa.002

Trends in small parts assembly automation

Miniaturization of products together with new type of integrated precision mechanical components such as miniature actuators, lenses, heads, mirrors, CCDs, etc. increase the demands in manufacturing and assembly. Today, most micro system technology products, such as microsensors, are manufactured using silicon-based technologies. On the other hand, the silicon-based micromachining infrastructure has been designed for massively parallel fabrication, where a large number of identical products are fabricated on a silicon wafer. Little or no assembly is needed in the fabrication of such monolithic products. When complex geometries or several materials are needed, however, assembly becomes essential.

Lot of research with grippers, manipulators and machine vision systems for microworld has been done over the last few decades. Most of this important work has concentrated on improving manual assembly or semi-automation methods. Using micro parts sets some extra demands for the assembly process. Firstly, as the dimensions of the parts are reduced to under one-millimeter scale, adhesive forces – such as van der Waals forces, electrostatic forces and surface tension – start to dominate gravity. These forces are a remarkable problem and set demands, e.g. for assembly environment and also cause serious problems in micro components assembly and handling. Secondly, as the tolerances of the parts are getting stricter they directly cause ever tighter precision demands for the assembly equipment. Research continues strongly, especially with different kinds of microgrippers, micromanipulators and miniature high-speed robots.

Until now, in industrial high volume mechanical assembly and sub-assembly applications, when the component size is somewhere between one millimetre and up to few millimeters, almost without exception this work has been done manually. However, there is an increasing need to automate this kind of work in high-labor-costs countries. There are companies, universities and research units especially in Japan and Korea that have concentrated on making research and development work in so-called meso-scale manufacturing and assembly areas. This means production where the object size is about 1mm, but accuracy demands for assembly and manufacturing systems are very high.

One important trend in micro and meso size assembly research is the miniaturization of production equipment, facilities and the ecological footprint of production. Microfactory means a small- size production system suitable for fabrication and manufacture of small size parts and products. It is also a general philosophy to minimize the production systems and processes to mate the products in size. The research in mini, micro and desktop factories originates from the early 1990s and has continued since then by developing the technological basis and different technological building bricks and applications in the field of high-precision manufacture and assembly of future miniaturized and micro products. This has paved the way to mini, micro and desktop factories which are seen as one potential solution for that kind of production, by improving space, energy and material resource utilization, and answering to the needs of design for postponement and customer-close customization and personalization. The research efforts done during these years are now increasingly leading also to commercialization and real industrial applications.

As a conclusion, miniaturization of products has been one of the most important technology trends in the last three decades. The future micro- and meso-scale products require manufacture of genuinely three-dimensional forms of different materials as well as joining of same and different materials together. In many cases human operators are no longer capable to assembling these products by hand. There is a need for a new level of seamless integration between fabrication, assembly and packaging technologies providing both challenges but also new possibilities for new breakthroughs in production and productivity of small products.

Ilpo KarjalainenConsultant at Institute of Production Engineering, Tampere University of Technology, Tampere, Finland