New Technology for Setting Up the Working Coordinate System in Micromilling

K. Popov(a), S. Dimov(a), A. Ivanov(a), D. T. Pham(a), E. Gandarias(b)
a: Manufacturing Engineering Centre, Cardiff University, Cardiff CF24 3AA, UK
b: Mondragon Goi Eskola Politeknikoa, Mondragon Unibertsitatea, Loramendi 4, 20500 Arrasate, Spain

Abstract

A major issue in micro milling is the setting up of the origins of the Machine Working Coordinate Systems (MWCS). The existing methods for carrying out this operation have an unacceptably high error along the Z axis, due to the spindle thermal enlargement, and are effective only when the machining is “relative” to other surfaces milled with one cutting tool within one operation. Therefore, more efficient technical solutions are required for setting up MWCS and to reduce further uncertainties associated with micro-milling operations.

This paper describes a new cost-effective method for setting up MWCS that applies a new technical solution for detecting the contact between the cutting tool and the workpiece. A prototype system was used to validate experimentally the accuracy and repeatability of the proposed method. The results obtained showed that the sensitivity of the system is sufficient to detect accurately the contact between the cutting tool and the workpiece, and thus to set up the MWCS origins. It was concluded that by applying this method it would be possible to minimise uncertainties introduced by the spindle thermal enlargement and touch probe run-outs in setting up micro machining operations. Also, the tests undertaken showed that the prototype system is reliable and convenient for use by machine operators.