Accuracy estimation of drilled holes with small diameter and influence of drill parameter on the machining accuracy when drilling in mild steel sheet

The miniaturization of component parts has advanced in the modern industrial product sector. Corresponding with this new wave, there is a strong demand for the establishment of minute-scale techniques to manufacture products with high quality involving the drilling of small holes. Non-traditional machining techniques such as electro discharge machining can be applied to make small holes. However, there is much practical value if small holes can be made by the traditional drilling process. In this paper, a method for estimating the drilled hole accuracy using a Fourier series analysis is proposed and this method is applied to small holes 1 mm in diameter drilled in mild steel for machine structure use. As a result, it is clarified that the bending rigidity of drill and the thinning of the drill point exert a large influence on the drilled hole accuracy.