Micromanufacturing of Miniature Non-Circular Gears by WSEM Process

摘要

A growing emphasis on the miniaturization of products has led to the evolution of many micromanufacturing processes. Major challenges in micromanufacturing include very small size, complicated shape, nano-finishing requirements, nano-scale dimensional and geometrical tolerances, and poor machinability of materials of miniaturized products. Wire spark erosion machining (WSEM) and μ-WSEM processes have the capability to meet these challenges. Different types of miniature non-circular gears (MNCGs) (such as elliptical, eccentric, triangular, square, pentagonal, hexagonal, etc.) are used for generating variable output speed from constant input speed, stop-and-dwell motion, generation of functional motion, indexing mechanism, combined rotational and translational motion, replacing different micro-kinematic mechanisms, and to increase simplicity, compactness, and accuracy of micro-electro-mechanical systems (MEMS). Their typical applications include minimal-invasive surgery equipment, micro-drills in dental applications, hexapod systems, mini-copter, miniature drones in the form of bird, butterfly, and dragonfly, self-balancing robots, micro-actuators, micro-pumps, micro-motors, MEMS, and miniature mechanical systems without any lubricants. Miniature triangular gear can be used in micro-pipes of micro-robots which are widely used in medical, military, coal, and nuclear power plants. Manufacturing of MNCGs is very challenging due to the extremely small size of their teeth, their complicated profile, and nano-scale tolerances and surface quality requirements. It restricts their many applications despite their many advantages. This chapter presents details of net-shape manufacturing of elliptical, eccentric, triangular, square, and pentagonal MNCGs made of stainless steel 304 by WSEM process along with details of μ-WSEM process. Good surface quality and dimensional accuracy are achieved which will eliminate further post-processing of the WSEM manufactured MNCGs.