Development of ultra-precision abrasive machining of functional structured surfaces

Current techniques for the manufacture of functional micro scale surface structures are both time consuming and expensive. Techniques for Ultra-Precision (UP) abrasive machining of functional surfaces, using specially manufactured tools, have previously been described for example in the grinding of riblets. However these methods are both costly and limited in their functionality. Using conventional UP grinding tools and a novel dressing technique, adapted from macro scale grinding, provides an alternative solution offering both low cost and ease of adaptability. Such a system would be capable of producing regular deterministic surface textures over a large area to a depth of 10-20μm grinding in single or multiple passes. To achieve this, the grinding wheel surface is shaped with specialised geometries using a single point diamond dressing tool. The required geometry for a given surface texture can be modelled and used to design a dressing solution consisting of a dressing depth and feedrate. Adapting a conventional grinding machine (Precitech Nanoform 250 Ultra-Grind) for such a process presents many technical challenges to overcome. The quality of the finished surface will be dependent on the accuracy of the dressing process and the tool/workpiece interaction. Methods for controlling and measuring the dressing depth, feedrate, spindle speed and runout have been designed and trialled to determine the feasibility of the process. The results of the trials have been compared against the model to determine the deviation from ideal and hence the quality of the finished surface