Krzysztof Jemielniak

• Prof. dr hab. inż.
• Professor (Full) at Warsaw University of Technology

Self-excited vibration is a significant constraint on productivity and production quality, which makes various forms of virtual machining widely used to find stable conditions before starting the actual machining operation. Numerical simulation of self-excited vibration, although much slower than analytical solutions, makes it possible to consider...

There are many algorithms for the identification of gradual tool wear (GTW) which usually counts in minutes and the detection of catastrophic tool failure (CTF) which counts in milliseconds. However, the tool may lose its cutting ability by accelerated tool wear (ATW), which may last several seconds and cannot be sensed either by GTW or CTF detecti...

This is the full version of a keynote paper presentation on XXXII CIRP Sponsored Conference on Supervising and Diagnostics of Machining Systems, KARPACZ, Poland 27th June – 1st July 2021

The paper presents an update of the recent literature on advances in machining of difficult to machine materials such as nickel and titanium-based alloys, and composites used in aeroengine and aerostructure applications. The review covers the following issues: advances in high-performance cooling techniques as cryogenic machining, minimum quantity...

Implementation of robust, reliable tool condition monitoring (TCM) systems in one of the preconditions of introducing of Industry 4.0. While there are a huge number of publications on the subject, most of them concern new, sophisticated methods of signal feature extraction and AI based methods of signal feature integration into tool condition infor...

Automatic tool condition monitoring is based on the measurements of physical phenomena which are correlated with the tool wear, and thus can be exploited as the tool wear symptoms. However measured quantities depend not only on the tool wear but also on a variety of other process parameters of random nature, making the relationship between tool wea...

Simulation of machining is increasingly becoming an indispensable tool in the process of production preparation. At the same time, more and more complex models of the division of the uncut chip cross section in determining of the cutting forces are being observed, which does not necessarily increase the reliability of the results. This article intr...

Wśród klasycznych metod kształtowania, obróbka skrawaniem zajmuje pozycję dominującą. Wynika to z dokładności obróbki oraz elastyczności. W książce przedstawiono aktualny stan wiedzy w zakresie: • Nowoczesnych materiałów narzędziowych • Procesów tworzenia wióra, sił skrawania i zjawisk cieplnych, • Zużycia i trwałość ostrza oraz skrawalności mater...

A comprehensive characterization of the near surface formed during the interrupted high-speed dry ceramic milling of IN718 was performed using light imaging, SEM/EDX, TEM and nano-hardness methods. It was found out that even an initial cut by a fresh tool creates a sub-surface alteration roughly 20 µm deep. The depth of altered sub-surface progress...

Fundamental importance for the stability analysis results has assumed model of the dynamic cutting coefficients. In most cases it is based on the model of cutting forces in steady state conditions. The models most often used are based on Kienzle power function and linear, proposed by Altintas. The paper presents interdependence of these models and...

The paper presents determination of dynamic cutting force coefficients by direct measurements of instantaneous cutting forces during vibratory cutting. The method exploits a special test rig consisting of a dynamometer supported by flat springs. The dynamometer with the cutting tool vibrates in the feed direction during orthogonal cutting. The meas...

A self-excited vibrations (chatter) are one of the most important limitation in machining performance and quality of finished parts as it is affecting its dimensional and geometrical accuracy. Selection of stable spindle speed can suppress self-excited vibrations occurrence, by disrupting regenerative effect. These and other technics can be tested...

Self-excited vibrations significantly reduce the milling productivity, deteriorate the quality of machined surface and tool life. One of the ways to avoid these vibrations is to modify the cutting parameters based on the stability analysis results. A method of numerical simulation of self-excited vibrations in the time domain can be used for this p...

This article presents a new tool wear multiclass detection method. Based on the experimental data, tool wear classes are defined using the Douglas–Peucker algorithm. Logical analysis of data (LAD) is then used as machine learning, pattern recognition technique for double objectives of detecting the present tool wear class based on the recent sensor...

Automatic tool condition monitoring is based on the measurements of physical phenomena which are correlated with this condition. There are numerous signal features (SFs) that can be extracted from the signal. As it is really not possible to predict which signal features will be useful in a particular case they should be automatically selected and c...

This paper presents a methodology aimed at the identification of a catastrophic tool failure (CTF) in turning processes based on multiple sensor monitoring. Experimental turning tests were carried out under various cutting conditions (cutting speed, feed, depth of cut) using a multi-sensor monitoring system consisting of a triaxial force sensor to...

For many years there has been considerable research from both an academic and industrial perspective into the monitoring and control of CNC machining processes, and progress has been well documented. It is widely acknowledged within the CIRP community that collection of information into the performance of material cutting processes is a worthwhile...

Robust tool condition monitoring system requires reliable, repeatable selection of representative segments of the sensor signals. In commercial TCM systems and most of laboratory ones useful signal segments are selected by the system user, which is difficult, inconvenient, prone to random changes of cutting conditions and human errors. The paper pr...

This paper presents the methodology of measuring the instantaneous cutting forces during vibratory cutting. It is based on elastically supported dynamometer vibrating with the tool during chatter. Acceleration of the dynamometer measured simultaneously allows for evaluation and elimination of inertia forces acting on the oscillating dynamometer. Di...

The research work carried out in this paper presents a novel intelligent tool condition monitoring solution for the turning process using an enhanced adaptive neural fuzzy inference system based on extended subtractive clustering. The hybrid system is constructed from training a takagi-sugeno-kang fuzzy logic system by integrating machining paramet...

Dynamic compliance of machine tool spindle is a necessary input for stability limit prediction. It can be determined by a single input–single output modal analysis, so called tap test. Despite methodology of modal analysis is well known for many years and there are several commercially available software packages supporting it, executing the experi...

The paper presents the method of the direct measuring the instantaneous cutting forces during chatter. This method is based on elastically supported dynamometer vibrating with the tool, on measuring the force and acceleration simultaneous, as well on measuring the displacement of the dynamometer and cutting tool during orthogonal turning, measured...

The classic approach to stability analysis in milling is based on the frequency response function (FRF) of the system obtained by the impact test. Application of this technique for a flexible workpiece with variable dynamics such as thin-walled structures may be difficult or impossible because the modal parameters of a part change due to material r...

The classic approach to stability analysis in milling is based on the frequency response function (FRF) of the system obtained by the impact test. Application of this technique for a flexible workpiece with variable dynamics such as thin-walled structures may be difficult or impossible because the modal parameters of a part change due to material r...

This paper presents a multiple sensor automatic data acquisition system deployed on a CNC turning center in a real- time production environment at Schivo Precision, Waterford, Ireland. The machine has been fitted with a variety of sensors measuring acoustic emission, cutting force & vibration installed at the turret of the machine, coupled with an...

This paper presents a multiple sensor automatic data acquisition system deployed on a CNC turning center in a real-time production environment at Schivo Precision, Waterford, Ireland. The machine has been fitted with a variety of sensors measuring acoustic emission, cutting force & vibration installed at the turret of the machine, coupled with an a...

Prediction of cutting forces is very important for the design of cutting tools and for process planning. This paper presents a fuzzy modelling method of cutting forces based on subtractive clustering. The subtractive clustering combined with the least-square algorithm identifies the fuzzy prediction model directly from the information obtained from...

Reliable tool life estimation of cutting tool in micromilling is essential for planning machining operations for maximum productivity and quality. This chapter presents type-2 fuzzy tool life estimation system. In this system, type-2 fuzzy analysis is used as not only a powerful tool to model acoustic emission signal features, but also a great esti...

Reliable prediction of cutting forces is essential for micromilling. In this paper, a fuzzy cutting force modelling method based on subtractive clustering method filters the noise and estimates the instantaneous cutting forces using observations acquired by sensors during cutting experiments. In the experimental case study, four data sets of microm...

Machining stability is one of the most important factors influencing the geometrical and dimensional accuracy of the machined parts. Regenerative chatter is a major limitation to the productivity and quality of machining operations due to poor surface finish and faster tool wear. In general there are two methods of stability analysis: solution of d...

The paper presents some aspects of turning of difficult to machine materials with self-propelled rotary tools (SPRT). The main criterion of the rotary tools performance was the attainable surface quality, waviness and adhered chips. The dependence of the insert rotational speed on cutting parameters was also investigated. Original method of measure...

Important indicator of milling machine tool condition is the dynamic compliance of its spindle. It can be identified with experimental modal analysis (tap test). The paper presents the methodology, algorithms and software for automatic SISO modal analysis. It enables performing of such test and obtaining proper results by an operator without any kn...

This paper presents a tool wear monitoring strategy based on a large number of signal features in the rough turning of Inconel 625. Signal features (SFs) were extracted from time domain signals as well as from frequency domain transforms and their wavelet coefficients (time–frequency domain). All of them were automatically evaluated regarding their...

This paper presents an experimental study for turning process in machining by using Takagi–Sugeno–Kang (TSK) fuzzy modeling to accomplish the integration of multi-sensor information and tool wear information. It generates fuzzy rules directly from the input–output data acquired from sensors, and provides high accuracy and high reliability of the to...

The analysis of Acoustic Emission (AE) signal generated from metal cutting processes has often approached statistically. This is due to the stochastic nature of the emission signal as a result of factors effecting the signal from its generation through transmission and sensing. Different techniques are applied in this manner, each of which is suita...

Prediction of process stability in milling is usually based on experimental frequency response functions of machine tool and cutting force model. Alternatively, operational modal analysis may be applied for the prediction of a stability diagram. It does not require modal impact test but uses vibration signal acquired during actual cutting to identi...

CIRP has had a long history of research and publication on the development and implementation of sensor monitoring of machining operations including tool condition monitoring, unmanned machining, process control and, more recently, advanced topics in machining monitoring, innovative signal processing, sensor fusion and related applications. This ke...

Cutting forces prediction is very important in micromilling for cutting tool's design and process planning. This paper presents a new model for uncertainty estimation of dynamic cutting forces in micromilling using a type-2 fuzzy rule-based system. The type-2 fuzzy estimation not only filters the noise and estimates the instantaneous cutting force...

In this paper, type-2 fuzzy logic system is applied to analyse acoustic emission signal feature for tool condition monitoring in a tool micromilling process. To make the comparison and evaluation of AE signal features easier and more transparent, Type-2 fuzzy analysis is used as not only a powerful tool to model AE SFs, but also a great estimator f...

The paper presents a new efficient method of evaluation of relevancy of signal features extracted from the wavelet coefficients of raw AE signal while rough turning of Inconel 625. Several meaningful signal features were automatically extracted from band pass signals using 22 different wavelets and used for tool condition monitoring. Accuracy of to...

Nickel-based superalloys are widely used in the aircraft industry since they are exceptionally thermal resistant, retaining their mechanical properties at temperatures of up to 700 °C. On the other hand, since they are very difficult to machine, tool life is typically short and can finish abruptly. As catastrophic tool failure can destroy an expens...

The paper presents acoustic emission and cutting force signals application in tool condition monitoring in micro-milling of cold-work tool steel. The results obtained revealed strong influence of tool wear on acoustic emission signal, providing acceptable results even while used separately. The signal was easy to register, and showed a very short r...

This paper presents a tool condition monitoring approach using Takagi-Sugeno-Kang (TSK) fuzzy logic incorporating a subtractive cluste- ring method. The experimental results show its effectiveness and satisfactory comparisons with several other artificial intelligence methods.

This paper presents a tool wear monitoring strategy in micromilling of cold-work tool steel, 50 HRC with a ball endmill d = 0.8 mm. The strategy is based on a large number of AE and cutting forces signal features and a hierarchical algorithm. In the first stage of the algorithm, the tool wear is estimated separately for each signal feature. In the...

This paper draws on the activities of the CIRP Collaborative Work on “Round Robin on Chip Form Monitoring” carried out within the Scientific-Technical Committee Cutting (STC-C). This collaborative work involved the following main round robin activities: (a) generation, detection, storage and exchange of cutting force sensor signals obtained at diff...

This paper reports on the activities of a joint research project work carried out by two Laboratories at the Warsaw University of Technology, Poland, and the University of Naples Federico II, Italy. The joint research work comprised the following main activities: (a) generation, detection, and storage of cutting force sensor signals obtained during...

Most tool-condition-monitoring (TCM) strategies are founded on the assumption that the monitored diagnostic signal feature is increasing, the monotonic function of the tool wear, but this is not always the case. The paper presents the TCM strategy based on non-monotonic signal features. The used-up portion of the tool life (Delta T=t/T) was used as...

The paper presents a comparison of efficiency of tool wear monitoring strategies based on one signal feature, on a single neural network with several input signals, and on a hierarchical algorithm and a large number of signal features. In the first stage of the hierarchical algorithms, the tool wear was estimated separately for each signal feature....

Summary The paper presents the application of multi layer perceptron artificial neural network for the tool wear monitoring in turning. To simulate factory floor conditions, six sets of cutting parameters were selected and applied in sequence. Six configurations of input parameter were tested to reveal their usability. Subsequently, the network's s...

Fuzzy logic is an AI method that is being implemented in a growing number of different fields. One of these applications is tool wear monitoring. The construction of a fuzzy knowledge base from a set of experimental data by a human expert however, is a time consuming task, and hence, limits the expansion of the use of this AI method. Alternatively,...

W monografii omówiono elementy struktury oraz zadania układu DNiPS, a także główne przyczyny kolizji występujących w fazie obróbki. Na podstawie przeprowadzonych badań eksperymentalnych autor wysuwa własne propozycje co do symptomów zużycia narzędzia i ich identyfikacji. Dokonuje też analizy wielkiej liczby doniesień literaturowych dotyczących kome...

This paper describes an application of three artificial intelligence (AI) methods to estimate tool wear in lathe turning. The first two are “conventional” AI methods—the feed forward back propagation neural network and the fuzzy decision support system. The third is a new artificial neural network based-fuzzy inference system with moving consequent...

The acoustic emission (AE) sensor and the pre-amplifier either built-in or connected to the sensor are the key elements in any AE based tool condition monitoring (TCM) system. This paper provides an interpretation of some common AE signal distortions and possible solutions to avoid such problems. The first two are AE signal saturation and temporary...

Acoustic emission (AE) is rather a well-known form of non-destructive testing. In the last few years the technology of the AE measurement has been expanded to cover the area of tool condition monitoring. The paper presents some experience of Warsaw University of Technology (WUT) in such applications of AE. It provides an interpretation of common AE...

Research works concerning the utilisation of cutting force measures in tool condition monitoring usually present results and deliberations based on laboratory sensors. These sensors are too fragile to be used in industrial practice. Industrial sensors employed on the factory floor are less accurate, and this must be taken into account when creating...

One of the most significant developments on the manufacturing environment is the increasing use of tool and process monitoring systems. Many different sensor types, coupled with signal processing technologies are now available, and many sophisticated signal and information processing techniques have been invented and presented in research papers. H...

Acoustic emission (AE) signal analysis is considered to be a very useful mean of on-line tool breakage detection. Many publications have proclaimed that catastrophic tool failure (CTF) causes an eminent peak in the AE signal. Therefore the magnitude of the AERMS signal has been considered as a measure of the CTF. While strong bursts of AE signals s...

Cutting forces and acoustic emission measures as a function of tool wear are presented for different cutting parameters and their applicability for tool condition monitoring is evaluated. The best of them, together with cutting parameters, were chosen as inputs to a feedforward, back propagation (FFBP) neural network; some training techniques were...

Acoustic emission (AE) is considered one of the main methods of on-line detection of catastrophic tool failure (CTF). Some strategies have claimed a subsequent increase of the root mean square value of the AE signal (AERMS) which in turn has been used as a measure of the CTF. However this measure was found to be not always sensitive to CTF. The aim...

Quest for process automation driven by growing costs of human labour and quality demands makes monitoring in manufacturing systems inevitable. Although numerous tool and process condition monitoring systems are now available in the market and many have been installed in industry, users generally still consider them unreliable, often not worth money...

The paper presents a digital detector of the cutting edge chipping or breakage based on the characteristic variation of the cutting force, associated with the battle catastrophic tool failure The results of tests of the detector operation, during which a laboratory dynamometer and industrial force sensors have been used are also presented.

A new theory to determine the dynamic cutting coefficients from steady state cutting data for three dimensional cutting has been developed. It is based on direct measurements of cutting forces, without any hypothesis relating to the steady state cutting. The experimental results show fairly good coincidence with the theoretical prediction of the st...

In this paper, basic relationships and algorithms for numerical simulation of non-linear, self-excited vibrations in single degree-of-freedom cutting systems are presented. Non-linearities due to the tool leaving the cut, as well as interference between the cutting tool clearance face and cutting surface waviness, were taken into consideration. Exa...

This paper deals with the analysis of regenerative chatter vibration. The assumptions and results of conventional stability analysis are discussed. The mechanism of a self-excited vibration frequency development process and its influence on vibration amplitude is studied. As a result the mechanisms of chatter frequency stabilization and modulation...

Automatic tool condition monitoring systems are regarded as an essential component of flexible manufacturing cells. A survey is made of tool condition appraising methods, and a classification of these methods is presented. Examples of tool condition monitoring systems that have been realized are cited. Some conclusions are reached concerning the pr...

It often happens In practice that the same tool is used In succession for cutting with various parameters. To predict the tool life in such cases an assumption is usally made that the further progress of tool wear of partly worn tool is independent of previous cutting conditions. The assumption make possible to assess the tool wear increments durin...