Concept for soft sensor structure for turning processes of AISI4140

Abstract

During turning of quenched and tempered AISI4140 surface layer states can be generated, which degrade the lifetime of manufactured parts. Such states may be brittle rehardened layers or tensile residual stresses. A soft sensor concept is presented in this work, in order to identify relevant surface modifications during machining. A crucial part of this concept is the measurement of magnetic characteristics by means of the 3MA-testing (Micromagnetic Multiparameter Microstructure and Stress Analysis). Those measurements correlate with the microstructure of the material, only take a few seconds and can be processed on the machine. This enables a continuous workpiece quality control during machining. However specific problems come with the distant measurement of thin surface layers, which are analyzed here. Furthermore the scope of this work is the in-process-measurement of the tool wear, which is an important input parameter of the thermomechanical surface load. The availability of the current tool wear is to be used for the adaption of the process parameters in order to avoid detrimental surface states. This enables new approaches for a workpiece focused process control, which is of high importance considering the goals of Industry 4.0.

Information reuse of nondestructive evaluation (NDE) data sets

“…This circumstance contradicts current digitization strategies, in which the availability and networking of information represent an essential basis for optimizing process steps or predicting maintenance intervals, for example. At the same time, nondestructive evaluation methods are a valuable source of data, since NDE results always contain qualitative or quantitative information regarding the properties and defects of components (Böttger et al, 2020).…”

Micromagnetic and Microstructural Characterization of Ferromagnetic Steels in Different Heat Treatment Conditions

“…The use of micromagnetic NDT in manufacturing and quality control is well-established for the efficient assessment of specific material properties [1,2]. Micromagnetic techniques offer great potential for the characterization of mechanical and microstructural properties of ferromagnetic material states [3][4][5][6][7]. Furthermore, due to the non-destructive and, in many cases, contactless measuring technique, micromagnetic NDT offers excellent opportunities for in-process measurements for process monitoring during transient machining processes of ferromagnetic materials [8].…”

“…For this purpose, specimens from two low-alloy steel materials in different heat treatment conditions have been investigated. The materials-AISI 52100 and AISI 4140-were used in hardened, and in quenched and tempered conditions, respectively because, on the one hand, they are widely used in industrial applications such as rolling bearings and automotive steering components after their final machining [7,12], and, on the other hand, these steel grades have a broad variety of mechanical properties, which are decisive for industrial application, and can be realized by heat treatment. By selecting the appropriate heat treatment parameters, quenching and tempering offer the possibility of adapting the hardness and the retained austenite (RA) content of the material to different requirements before machining [13].…”

A2.3 - Information recycling of NDE data sets

“…But besides this, NDE methods can be valuable data suppliers for the optimization of e.g., manufacturing processes [1]. However, this is currently affected by the fact that NDE data sets usually do not guarantee a uniform structure, data format or the completeness of all relevant information.…”