Papers by Robert Tomkowski
Micromachines, 2021
Friction control is a vital technology for reaching sustainable development goals, and surface te... more Friction control is a vital technology for reaching sustainable development goals, and surface texturing is one of the most effective and efficient techniques for friction reduction. This study investigated the performance of a micro-dimpled texture under varying texture densities and experimental conditions. Reciprocating sliding tests were performed to evaluate the effects of the micro-dimpled texture on friction reduction under different normal loads and lubrication conditions. The results suggested that a micro-dimpled texture could reduce the coefficient of friction (CoF) under dry and lubricated conditions, and high dimple density results in a lower CoF. The dominant mechanism of the micro-dimpled texture’s effect on friction reduction was discussed, and surface observation and simulation suggested that a micro-dimpled texture could reduce the contact area at the friction interface, thereby reducing CoF.
The Barkhasuen Noise Measurements : Good Practice Guide
The KTH Royal Institute of Technology (Stockholm, Sweden) as a project leader allowed strengtheni... more The KTH Royal Institute of Technology (Stockholm, Sweden) as a project leader allowed strengthening collaboration between academic and industrial experts in the field of non-destructive testing (ND ...
Metodyka oceny zdolności klasyfikacyjnej parametrów charakteryzujących cechy stereometryczne nierówności powierzchni
The increase in requirements for accuracy and properties of elements, minimisation of the wear of... more The increase in requirements for accuracy and properties of elements, minimisation of the wear of materials, mass and dimensions of elements, the increase in load capacity and endurance, and also the development of manufacturing technology, lead to the development of many measurement methods and equipment to carry them out as well as to increase the number of parameters for use in evaluation of the surface stereometry features. Taking into account new requirements, a new system for evaluation of the surface stereometry features was developed. The system consists of a collection Dr inz. Dariusz LIPIŃSKI
Penetration depth investigation of Barkhausen noise signal for case-hardened components
Non-destructive testing of layer properties in machine part loading, has greatly improved over th... more Non-destructive testing of layer properties in machine part loading, has greatly improved over the last 20 years. One of those NDT methods is Barkhausen Noise Analysis (BNA). The BNA-method is util ...
High precision 3D evaluation method for Vickers hardness measurement
CIRP Annals, 2020
Abstract Hardness measurement is a vital step for quality assurance in manufacturing of a wide ra... more Abstract Hardness measurement is a vital step for quality assurance in manufacturing of a wide range of products. Today, the standard hardness measurement tests, such as Vickers, are based on microscope image-based evaluation methods. Since these methods are limited to the geometry of the indentation in 2D images, their precision are highly dependent on the samples’ surface finish. A novel method based on 3D surface topography of the indentation is introduced for more robust Vickers hardness measurement. The 3D evaluation method with information in Z direction offers a high level of precision in hardness measurement on surfaces with different surface qualities.
Metals, 2020
Controlling friction and wear are essential for reducing energy loss and lengthening the life spa... more Controlling friction and wear are essential for reducing energy loss and lengthening the life span of friction pairs in sliding contacts. Surface texturing is an effective and efficient way to reduce friction and wear, especially under lubricated conditions. Dimple texture on friction pair surfaces has been verified to enhance the lubrication condition and shift the lubrication regime by generating additional hydrodynamic pressure. However, the geometric features and distribution of the microstructures considerably influence the production of additional pressure. Choosing and designing dimple texture with suitable geometric features is necessary and important for texturing applications. In this study, computational fluid dynamics (CFD) are used to investigate the effect of the geometric features of dimple textures on pressure build-up. The influence of dimple shapes, dimple depths, minimum film thickness, dimple densities, and dimple surface angles are presented and discussed. Notab...
PeerJ, 2016
BackgroundTermination of fixed orthodontic treatment is associated with bracket debonding and res... more BackgroundTermination of fixed orthodontic treatment is associated with bracket debonding and residual adhesive removal. These procedures increase enamel roughness to a degree that should depend on the tool used. Enamel roughening may be associated with bacterial retention and staining. However, a very limited data exists on the alteration of 3D enamel roughness resulting from the use of different tools for orthodontic clean-up.Aims1. To perform a precise assessment of 3D enamel surface roughness resulting from residual adhesive removal following orthodontic debonding molar tubes.2. To compare enamel surfaces resulting from the use of tungsten carbide bur, a one-step polisher and finisher and Adhesive Residue Remover.Material and MethodsBuccal surfaces of forty-five extracted human third molars were analysed using a confocal laser microscope at the magnification of 1080× and 3D roughness parameters were calculated. After 20 s etching, molar tubes were bonded, the teeth were stored i...
Medical science monitor : international medical journal of experimental and clinical research, Jan 20, 2014
After orthodontic treatment, brackets are debonded and residual adhesive is removed, causing iatr... more After orthodontic treatment, brackets are debonded and residual adhesive is removed, causing iatrogenic enamel damage. The aim of this study was to review the methods of orthodontic adhesive removal, find clear evidence, and provide a rationale for this procedure. A literature search was performed in PubMed, Dentistry and Oral Sciences, Scopus, Cochrane, Google, and Google Scholar using keywords: orthodontic adhesive removal, orthodontic debonding, orthodontic clean-up. Studies concerning human enamel roughness or loss from debonding and adhesive removal were considered. Forty-four full-text articles were analyzed and 3 were rejected after detailed reading; finally 41 papers were included. Fifteen qualitative studies, 13 studies based on indices of enamel surface, and 13 quantitative studies were found. No meta-analysis could be performed due to a lack of homogenous quantitative evidence. The most popular tools were tungsten carbide burs, which were faster and more effective than So...
Sensors, 2019
Barkhausen noise testing (BNT) is a nondestructive method for investigating many properties of fe... more Barkhausen noise testing (BNT) is a nondestructive method for investigating many properties of ferromagnetic materials. The most common application is the monitoring of grinding burns caused by introducing locally high temperatures while grinding. Other features, such as microstructure, residual stress changes, hardening depth, and so forth, can be monitored as well. Nevertheless, because BNT is a method based on a complex magnetoelectric phenomenon, it is not yet standardized. Therefore, there is a need to study the traceability and stability of the measurement method. This study aimed to carry out a statistical analysis of ferromagnetic samples after grinding processes by the use of BNT. The first part of the experiment was to grind samples in different facilities (Sweden and Finland) with similar grinding parameters, different grinding wheels, and different hardness values. The second part was to evaluate measured BNT parameters to determine significant factors affecting BNT sign...
High-accuracy surface topography measurements of abrasive tools using a 3D optical profiling system
Friction control is a vital green technology for reaching sustainable development goals, and surf... more Friction control is a vital green technology for reaching sustainable development goals, and surface texturing is effective and efficient at reducing friction. In this study, a novel preparation scheme involving dimpled groove texture is proposed. A pulsed laser marking system is used to make the dimpled grooves. Due to the unique design and process to make the proposed texture, texturing time can be greatly minimized compared to the conventional micro-groove texture technology. A computational fluid dynamics (CFD) model that considers the dimple surface angle is employed to aid the design of the texture and to predict the performance of the texture under certain conditions. Reciprocating sliding tests are preformed to evaluate the effects of the texture on friction reduction. Textures with different densities are used in the experiments. The results suggest that the dimpled groove reduces the coefficient of friction by 6% with less density distribution on the sample surface; nevert...
Application Of The Hamming Network To The Classification Of Surfaces After Abrasive Machining
Journal of Machine Engineering
The use of artificial neural networks for modelling and inference about surface parameters is a m... more The use of artificial neural networks for modelling and inference about surface parameters is a more and more often undertaken research topic. Based on the analysis of the ranges of suitability of surface topography parameters, a variety of different parameters can be observed to identify surfaces with different features and different conditions of use. The issues of surface topography analysis and determination of surface condition after abrasive machining are of fundamental importance. Currently, when assessing the surface intended for interaction with the other surface, it is possible to use many surface evaluation parameters. Assigning the machined surface to the appropriate assessment group, especially in automated quality control systems, requires a preliminary surface classification. In this article Hamming's network was used for the surface classification along with modification of Hamming distance.
Towards the usage of image analysis technique to measure particles size and composition in wood-polymer composites
Industrial Crops and Products
The paper presents the method based on white light interferometry - SBI (Scanning Broadband Inter... more The paper presents the method based on white light interferometry - SBI (Scanning Broadband Interferometry). SBI uses a correlation algorithm to find the coherence peak and phase position of an interference pattern produced by a selectable bandwidth light source. It provides both high resolution and excellent sensitivity of the returning light. This method can be applied to ultra precision assessment of wide range of surfaces. Measurements of different types of materials, including glass, metal, photo resist, polymer, liquid inks are also possible to be taken. In experimental investigations there was assessed the surface topography of DOEs (Diffractive Optical Elements). A sample containing 8 diffractive optical elements generating optical patterns in the form of single line, multi-lines and crosshair was used for measurements. The surfaces of the all DOEs were measured by an advanced measurement system Talysurf CCI 6000 produced by Taylor Hobson. The measurement data recorded were ...
In modern industry it is often required to improve the cleanliness and finish quality of surfaces... more In modern industry it is often required to improve the cleanliness and finish quality of surfaces of precise manufacturing parts. For this purpose, producers apply microfinishing [1], which permits to obtain the better quality than that obtained by different conventional finishing processes. This influences significantly the maintenance of proper operating parameters by manufactured parts. Microfinishing process is realized by means of various types of abrasive tools such as microfinishing films [2]. Manufacturers often make available incomplete or incorrect technical data concerning the stereometric characteristics of produced abrasive tools. This situation complicates the proper selection of the optimal machining parameters. In this case it is necessary to conduct investigations of the surface topography of the microfinishing film with use of precise measuring methods. This paper proves that such investigations can be carried out with use of advanced microscopy methods such as non...
Wybrane problemy oceny chropowatości i klasyfikacji topografii powierzchni
DESCRIPTION prezentacja - problemy oceny i klasyfikacji topografii powierzchni
Residual stresses influence, among other parameters, on the performance characteristics of the ma... more Residual stresses influence, among other parameters, on the performance characteristics of the machine, such as deformation, static and dynamic strength, material usage, or the strength of the contact. Extensional stresses as a result of abrasive machining reduce the fatigue strength for the dynamically loaded machine parts. It is preferred when the surface layer of the compressive stress is obtained. Therefore, it is recommended to reduce or remove most of the tensile stresses in the elements of the machine, for example, by reducing the value of technological parameters (feed-in). Note also that the type of occurring stresses depends also on the characteristics of the used grinding wheel, where the importance has the type of selected abrasive material. Grinding, eg. grinding wheel with aloxite grain is almost always the occurrence of tensile stresses, in contrast to CBN, which causes the formation of an compressive stresses in the surface layer. The article presents the issues rela...
The application of the theory of fuzzy sets lets on the qualitative evaluation of the surface on ... more The application of the theory of fuzzy sets lets on the qualitative evaluation of the surface on the basis of parameters of the geometrical structure of surface. Enlarges this the communicability of the evaluation of the structure of the geometrical surface which is not described exclusively by the series often confounding of many parameters. This paper is introduced to evaluation the guild of surface stereometry on the example of amplitude parameters. The using of fuzzy logic methods makes possible the creation of the linguistic model which contains influence of each parameters describing the surface stereometry on the correct classification.
Application of the Laser Scanning Microscopy to Evaluation of Abrasive Tool Wear
Grinding is one of the basic precise machining methods. Evaluation of the abrasive tool surface i... more Grinding is one of the basic precise machining methods. Evaluation of the abrasive tool surface is the basic criterion of forecasting the tools' durability and the process results. The applied method of laser scanning made determination of the surface coordinates and subsequently of its geometric features with micrometric accuracy possible. Using the information on the abrasive tool surface geometric structure, a methodology of evaluation of the level of changes of the tool during the machining process was developed. The developed method allowed for evaluation of the level of abrasive tools' wear, and subsequently formed foundations for assessment of the influence of the machining parameters on the durability of abrasive tools, evaluation of the influence of the parameters of the process of shaping the abrasive tools' active surfaces on their geometric characteristic and evaluation of the level of correlation between the monitored process parameters and the degree of the...
One of the most important procedures in modern surface metrology is digital filtering. It is real... more One of the most important procedures in modern surface metrology is digital filtering. It is realized by many filters which are complicated mathematical tools for analysis of a wide variety of surface characteristics. In practice, filters are used among others for denoising, correcting the data obtained from measuring tools and displaying important characteristics of surfaces. The ISO committee is continuing works to develop the standards of the ISO 16610 group, concerning the digital filters. This group contains description of various filters, namely: linear profile filters (basic concepts – ISO/DIS 16610-20, spline filters - ISO/DIS 16610-22, spline wavelets – ISO/DIS 16610-29), morphological profile filters (basic concepts – ISO/DIS 16610-40, disk and horizontal line-segment – ISO/DIS 16610-41, scale space techniques – ISO/DIS 16610-49), robust areal filters (Gaussian regression filters – ISO/DIS 16610-71) and areal morphological filters (segmentation – ISO/DIS 16610-85). The pap...
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Papers by Robert Tomkowski