Surface roughness and forces prediction of milling Inconel 718 with neural network

The objective of the article is to indicate a tool that allows finding the relationship between cutting forces and surface roughness and variable cutting parameters and cutting tool wear. The tests were carried out on a workpiece of Inconel 718, machined with cemented carbide milling cutters. The article compares artificial neural networks and multiple regression. Multi-layer Perceptron networks with backward error propagation were used. Based on the conducted research, it was found that in the case of Inconel 718 machining, multiple regression is not a suitable tool for testing the relation analyzed in this article. The correlation (R²) for multiple regression is about 0.6 for forces and 0.25 for roughness. Neural networks have a correlation coefficient (R²) higher than 0,9.

I. Introduction

Modern industry often uses materials with special properties like nanocomposite [1], materials with improved surfaces [2] or super alloys. Such materials are used e.g. in the aviation or marine industry, for turbine rotors, exhaust valves, engine components. Materials used in these industries usually require high strength, good workability and high resistance to corrosion [3], [4]. One of the main groups among the super alloys are nickel-based alloys. Machining of these alloys is difficult due to the hardening of the material during machining, high temperature in the cutting zone, build-up on the cutting edge and the elastic recovery of the machined layer. Due to this, it is difficult to predict the value of wear of the cutting tool, which has a significant impact on the quality of the received surface [5]. For this reason, the surface quality after machining and the forces occurring during the operation are difficult to predict. In this process very important is accuracy. Accuracy is defined as the degree of conformance of an estimated or measured value to a defined reference value [6]. Surface roughness is one of the most important parameters, important not only in machining but also in casting, plastics processing or runway surfaces [7].