Developed in conjunction with Earlsdon Technology (E-Tech), the grinding machines use specialised tooling to achieve surface finishes with tolerances that the company believes are more accurate than anything previously achieved on high speed systems of this type. Jeff Kiernan, commercial director at Dawson Shanahan, explains: "We've seen a considerable increase in demand in recent years from customers looking for component parts produced to ever tighter tolerances – often to within a few microns – for both small batches and large volume production runs. As a result, we needed to expand our machining facilities, especially our grinding cells, to increase productivity while enhancing levels of quality and repeatability still further." Dawson Shanahan has worked closely with E-Tech to develop the new slot, groove and centreless grinding machines. Key to the successful operation of the machines has been the development of special purpose CBN grinding wheels, carried out by both companies in conjunction with the grinding wheel manufacturer, Asahi Diamond Industrial. These 400 mm diameter wheels typically operate at speeds of 4,000 rpm and are automatically balanced, to eliminate vibration, and dressed during operation, with the latter using in-situ diamond dressing wheels to maintain exact outer edge profiles and a long operating life. "We believe that we are reaching levels of precision for high speed grinding that are currently unrivalled by any other company in Europe", enthuses Mr Kiernan. "For example, we're producing finished components in 2.5 seconds that are machined to within 0.7 µm over a surface area of just 3.0 mm²; there is no need for further polishing or burr removal. Additionally, many of the parts that we manufacture typically incorporate slots with chamfered profiles ground into shafts measuring several millimetres in diameter; here we can hold tolerances of 20 minutes of a degree, which over an extremely small area equates to levels of precision of just a few microns."