ABSTRACT
266Mechanical elements and mechanisms form the foundational components that can be assembled to provide the manufacturing instruments and machines for producing anything from the large-scale (for example, ships, planes, trains and automobiles) to atomic-level fabrication (for example, lithography tools, and micro- and nano-electro-mechanical systems). Important principles that must be applied when designing, fabricating and using these machines and processes are outlined in other chapters in this book. Adherence to these principles is essential when precision is a major objective. This chapter considers those elements that are commonly utilised in precision machines not only in terms of performance, but also emphasises the limits of achievable precision and principles of installation so that these limits can be realised. While this chapter is mainly focused on motion guidance mechanisms, specific principles associated with stiffness and symmetry considerations are discussed, with a focus on the performance of integrated mechanisms. Operation and performance of specific machine elements are then reviewed, again focusing on limiting precision and the optimal conditions for this to be realised. These machine elements are split into two major categories: motion guidance mechanisms or ‘bearings’, and actuators that provide the motive power. The chapter concludes with a discussion of methods and mechanisms for coupling actuators to the motion systems.
