MaRoReS (Machining, Roughness and Residual Stresses generated in turning of 42CrMo4+QT steel)

Description

This repository is part of the MaRoReS (Machining, Roughness and Residual Stress) project, with which the authors aim to determine the influence of the main turning parameters (here feed rate (mm/rev), cutting speed (m/min), depth of cut (mm), and insert radius(mm)) on the roughness and residual surface stress of a 42CrMo4+QT steel. For this purpose, a large experimental campaign was designed using a CCD-type design of experiments in which 68 different specimens were machined under different cutting conditions. The turning process was fully monitored regarding forces, accelerations, sound, and current consumed by the lathe. Once the specimens were machined, surface roughness and longitudinal residual stress were measured. The repository is organized as follows. Initially, the user will find two folders: "Raw Data" and "Processed Data". On the one hand, the first folder is subdivided into 3 subfolders containing respectively the raw data obtained from the roughness measurement, the surface residual stresses, and the data obtained from monitoring the turning process. On the other hand, the second folder is dedicated to entering the post-processed data. A more detailed explanation of each folder can be found by double-clicking on them. In addition, in the section "Steps to reproduce", the reader will find an exhaustive explanation of the acquisition methods and the post-processing analysis implemented in each case.

Steps to reproduce

This section explains in detail the procedure followed in the realization of this experimental campaign so that any interested reader can repeat this procedure. According to the existing literature in the field consulted by the authors, the turning parameters that could have the most significant impact on the generation of surface stresses and roughness in alloy steel, such as 42CrMo4+QT, were initially selected. In this case, these parameters were: feed rate (mm/rev), cutting speed (m/min), depth of cut (mm) and the tool tip radius (mm). From these parameters, a full central composite design of experiments (CCD) was implemented using Design Expert v13 software, resulting in 68 different turning scenarios. During machining, the process was continuously monitored by measuring forces, accelerations in the tool holder, sound impact and current consumed by the lathe. For this purpose, an ad-hoc software was designed using LabView 2012 and all signals were recorded using two National Instrument data acquisition boards. Once the 68 specimens were machined, surface roughness was measured on each specimen at three different points using a Leica confocal microscope model Leica DCM3D according to UNE-EN-ISO-21920-3. The cut-off filter, λc , was equal to 0.8 mm and 7 repetitions were made, which conducts to the evaluation length of 5.60 mm. Paralelly, surface residual stresses were measured on the specimens using a Stresstech 3000-G3R X-ray diffractometer using the sin2 ψ technique. The {221} gamma lattice plane was examined under a 2θ angle of 156.1º, utilizing the Kα chromium wavelength (0.2291 nm).

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