The acoustic emission technique (AET) is a relatively recent entry into the field of nondestructive evaluation (NDE) which has particularly shown a very high potential for material characterization and damage assessment in conventional as well as nonconventional materials [3]. This method has also been widely used in the field of metal cutting to detect process changes like tool wear etc. In-process tool wear monitoring has presently acquired more importance than ever as manufacturing systems are increasingly requested to provide greater automation and flexibility, while keeping high productivity levels. In-process sensing techniques allowing for the optimal utilisation of tool life is highly desirable.

Over the last several years, the phenomenon of AE, i. e., transient elastic waves generated by the rapid release of energy from materials undergoing plastic deformation, fracture or both has been analysed with reference to machining processes, to identify the relationships between process parameters and detected signals. The AE response from metal cutting has been shown to change as the cutting tool is worn. Several research workers using different AE techniques have found correlations between the amount of flank or crater wear and various AE parameters [4].

The major advantage of using AE to detect the condition of tool wear is that the frequency range of the AE signal is much higher than that of the machine vibrations and environmental noises. Therefore, a relatively uncontaminated signal can be easily obtained by the use of a high pass filter. In addition, AE can be measured by simply mounting a piezoelectric transducer on the tool holder. It does not interfere with the cutting operation thus allowing for continuous monitoring of the tool condition [1].

In the present investigation the results obtained from the analysis of AE signal detected during turning tests of high carbon steel (EN-31) using uncoated carbide indexable inserts are presented and discussed. Various AE parameters like rise time, ring down count etc. have been used for monitoring tool wear. The feasibility of using acoustic emission technique as an in- process tool wear monitoring method is established. REFERENCES

1. S. Y. Liang and D. A. Dornfeld, "Tool Wear using Times Series Analysis of Acoustic Emission", ASME Journal of Engineering for Industry, 111, 199-205 (1989)
2. E. N. Diei andD. A. Dornfeld, "Acoustic Emission Sensing of Tool Wear in Face Milling", ASME Journal of Engineering for Industry, 109, 234-240 (1987)
3. C. R. L. Murthy and V. A. Chandramouli, "Training and Certificate Course on Acoustic Emission", conducted by Indian Society for Non Destructive Testing and Acoustic Emission Working Group (India), 1994
4. G. F. Michelletti, "Tool Wear Monitoring through Acoustic Emission", Annals of the CIRP, 38, 99-102 (1989).