221 Advances in Production Engineering & Management ISSN 1854‐6250 Volume 12 | Number 3 | September 2017 | pp 221–232 Journal home: apem‐journal.org https://doi.org/10.14743/apem2017.3.253 Original scientific paper Diagnostic of peripheral longitudinal grinding by using acoustic emission signal Zylka, L. a,* , Burek, J. a , Mazur, D. b a Department of Manufacturing Techniques and Automation, Rzeszow University of Technology, Poland b Department of Electrical and Computer Engineering Fundamentals, Rzeszow University of Technology, Poland ABSTRACT ARTICLE INFO Grinding burn is one of the well‐known problems in grinding processes. The phenomenon of burns causes permanent damage to the ground surface. Therefore, there is a need of monitoring the grinding processes in order to prevent surface damage of a workpiece. This paper presents a method of diagnosing grinding wheel wear with the use of acoustic emission signal gen‐ erated during grinding. The method aims to detect the occurrence of burn in the surface layer of ground workpieces, and, thus, to replace costly and trou‐ blesome surface layer control methods performed after grinding. Experi‐ mental research of the grinding process together with the control of surface layer condition was conducted by means of the nital etching method. A band analysis of acoustic emission signal was completed and the influence of the grinding burns phenomenon on the signal amplitude in the range of low fre‐ quencies was presented. A boundary value of the AE describing the appear‐ ance of grinding burns was determined. Moreover, RMS value of acoustic emission signal was analysed, and the influence of grinding wheel wear on the signal variations was determined. A new parameter was proposed in order to determine the end of grinding wheel life‐time. A boundary value of this AE parameter, which indicates the excessive wear of grinding wheel was deter‐ mined. © 2017 PEI, University of Maribor. All rights reserved. Keywords: Grinding Grinding burns Grinding wheel Diagnostic Acoustic emission *Corresponding author: zylka@prz.edu.pl (Zylka, L.) Article history: Received 5 May 2017 Revised 6 July 2017 Accepted 10 July 2017 1. Introduction Grinding is classified as after‐machining and, therefore, it is usually the last step of a technologi‐ cal process. Therefore, grinding and its result determine final parameters of the manufactured parts, which have a direct influence on their operational properties [1]. A very important aspect is ensuring the correct grinding process, namely acquiring the assumed quality parameters of the manufactured products, which include, among others, the condition of the surface layer after machining [2]. Currently, in industrial production the control of surface layer damage of the ground surfaces is done by means of many control methods, often very time‐consuming or harmful for the natural environment [3, 4]. Additionally, the use of such methods as fluorescent, magnetic or nital etching ones requires high qualifications from the employees. These measure‐ ments are done after machining, thus, approving or rejecting the results of machining. One type of surface layer damage that completely excludes a workpiece from usage are grind‐ ing burns. The term grinding burn refers usually to the altered structure of the ground surface layer of a workpiece, generated in a result of external, thermal influence of contact area of a grinding wheel with a workpiece [5‐7]. Irrespectively from the kind of the resultant grinding