A review of recent developments in the design of special-purpose machine tools with a view to identification of solutions for portable in situ machining systems

With the ever increasing diversity of manufacturing and maintenance needs for modern products, the realm of machine tool design has expanded considerably in recent years. While machine tools for producing singular parts are widely documented, there is much less information available about machine tools for specialist tasks such as repair and maintenance. The paper aims to give an overview of the developments in the field of specialist machine tools and machining systems with a particular emphasis on maintenance operations and in situ machining. The difficulties of performing maintenance on large-scale systems are outlined along with the potential benefits of in situ machining in these applications. A number of examples of specialist machines for applications in various fields are described. The developing area of micro machine tools and micro factories is introduced along with examples of systems which have been developed or proposed. The possible advantages and draw-backs of the various technologies described are discussed. The paper goes on to comment on the potential for a new approach which combines these technologies to produce small in situ machine tools for performing macro-scale machining operations on large workpieces. These machining systems could offer increased versatility of in situ maintenance machining, compared to machines designed for a single repair operation, while reducing costs and environmental impacts.