Development of an ultra-precision grinding technique for the production of structured micro-patches on ceramics and tool steel

Ultra-precision grinding using super abrasives such as diamond and Cubic Boron Nitride (CBN) is ideally suited to the production of artefacts in hard or brittle materials such as ceramics or hard metals. These materials are well suited to the production of moulds. Conventional ultra-precision machining techniques such as diamond turning or micro milling are of limited use in the production of these moulds due to long processing times and incompatibility with certain materials. Moulds incorporating a variety of functional surface structures are used in the production of low cost items such as optics and micro-fluidics.

Ultra-precision grinding utilising wheels dressed with specialised surface geometries presents an attractive alternative method for the production of structured surfaces. This method has the advantage of being low cost and easy to adapt to a variety of applications. Developing on previous work a series of radial grooves at regular intervals were dressed onto grinding wheels and then used in two perpendicular passes. The technique has been used to create a series of micro-patches on Macor® ceramic to a depth of 15μm with side lengths of approximately 200μm to 300μm. The results of the operation have been compared against the ideal model to determine the fidelity of structure transfer and assess the quality of the finished surface and the impact of process control factors.