Selected Mechanical and Rheological Properties of Medical Resin MED610 in PolyJet Matrix Three-Dimensional Printing Technology in Quality Aspects.

In connection with the growing demand of the medical and medicine-related industry for materials exhibiting biocompatible properties used as part of three-dimensional (3D) printing additive technologies. The article presents research results concerning rheological and selected mechanical properties of a modern, photocurable MED610 resin, which is also used mainly in medicine, as well as dentistry. The article also shows extensive results of testing bending stress relaxation and creep, as well as the tensile strength of samples created with the PolyJet Matrix (PJM) technology. The authors used various sample types, including ones of unique shape and a hexagonal cellular structure. The analysis of the impact of element orientation on the working platform of the machine (3D printer) on the obtained test results (so-called printing direction-Pd) was also taken into account as a key technological parameter of the 3D printing process. Experimental rheological curves were matched with theoretical curves resulting from the application of a five-parameter Maxwell-Wiechert (M-W) model in the case of stress relaxation and a five-parameter Kelvin-Voigt model for creep. Very good matches were achieved, mean coefficients Chi2 = 0.0014 and R2 = 0.9956 for matching the five-parameter M-W model and mean coefficients Chi2 = 0.000006 and R2 = 0.9992 enable recommending the obtained results to be used for various engineering calculations, especially computer simulations. Moreover, the use of relaxation curves can significantly increase the construction capabilities within the design process, which includes the MED610 material.

Multiscale Analysis of Functional Surfaces Produced by L-PBF Additive Technology and Titanium Powder Ti6Al4V.

The article discusses experimental studies assessing the possibility of mapping surfaces with a characteristic distribution of irregularities. Tests involved surfaces produced using the L-PBF additive technology, using titanium-powder-based material (Ti6Al4V). An evaluation of the resulting surface texture was extended to cover the application of a modern, multiscale analysis, i.e., wavelet transformation. The conducted analysis that involved using selected mother wavelet enabled production process errors and involved determining the size of resulting surface irregularities. The tests provide guidelines and enable a better understanding of the possibility of producing fully functional elements on surfaces, where morphological surface features are distributed in a characteristic way. Conducted statistical studies showed the advantages and disadvantages of the applied solution.

The Effect of Non-Measured Points on the Accuracy of the Surface Topography Assessment of Elements 3D Printed Using Selected Additive Technologies.

The paper presents the results of research aimed at evaluating the surface topography including the analysis of the number of unmeasured points of the samples 3D printed using four additive technologies (i.e., PolyJet Matrix, fused deposition modeling, selective laser sintering, and selective laser melting). The samples were made in three variants of location on the printing platform of 3D printers. Measurements of the samples' surface topography were carried out using a Talysurf CCI Lite optical profilometer and a Talysurf PGI 1230 contact profilometer. The percentage of non-measured points for each sample and the parameters of the surface topography were determined. Then, the non-measured points were complemented and the topography parameters for the corrected surface were recalculated. In addition, to perform comparative measurements, each surface was measured using a contact profilometer Talysurf PGI 1230. Preliminary results of the research showed that the measurement of the surface topography of the samples made using selective laser sintering technology with the Taysurf CCI optical measuring system is very unreliable, as the number of non-measured points for the analyzed samples was higher than 98%. The highest accuracy of optical measurement was obtained for PJM technology and three variants of location on the printing platform of the 3D printer.

Basic Design Parameters Influencing on Axial Stiffness of the Spiral Wound Gasket.

The article presents the influence of important design parameters of a spiral gasket on axial stiffness and leakage level. These parameters were the angle of inclination of the central part of the spiral section, the length of the vertical part of the spiral section, and the degree of densification of the material filling the metal coils. The scope of work was divided into two stages. In the first, experimental tests were conducted to determine the stiffness and tightness of a standard spiral gasket at two extreme levels of densification of the filler material, and the elastic-plastic properties of expanded graphite, which is the filler material of the metal spirals, were determined. In the second stage, multivariate numerical calculations were carried out to determine the axial stiffness of the gasket and to evaluate the distribution of contact pressure on the sealing surface. A novel aspect of the work is the proposal of a mathematical model to estimate the averaged value of the modulus of elasticity of the filler material as a function of the degree of densification and the execution of an experimental plan that significantly allowed the adoption of a limited number of analysed model variants used in the numerical calculations.

Possibilities of a Hybrid Method for a Time-Scale-Frequency Analysis in the Aspect of Identifying Surface Topography Irregularities.

The article presents research results related to assessing the possibilities of applying modern filtration methods to diagnosing measurement signals. The Fourier transformation does not always provide full information about the signal. It is, therefore, appropriate to complement the methodology with a modern multiscale method: the wavelet transformation. A hybrid combination of two algorithms results in revealing additional signal components, which are invisible in the spectrum in the case of using only the harmonic analysis. The tests performed using both simulated signals and the measured roundness profiles of rollers in rolling bearings proved the advantages of using a complex approach. A combination of the Fourier and wavelet transformations resulted in the possibility to identify the components of the signal, which directly translates into better diagnostics. The tests fill a research gap in terms of complex diagnostics and assessment of profiles, which is very important from the standpoint of the precision industry.

Analysis of Technological Heredity in the Production of Rolling Bearing Rings Made of AISI 52100 Steel Based on Waviness Measurements.

The production of rolling bearings is a complicated process that requires the use of many operations. The manufactured elements of rolling bearings should be of high quality while minimizing production costs. Despite many research studies related to the analysis of technological processes, there is still a lack of research and tools allowing us to satisfactorily assess the relationships between individual operations of the rolling bearing ring process of production and the quality. To perform such an assessment, one can use the concept of technological heredity phenomenon analysis. As the surface waviness of the bearing race is of key importance, the present paper aims at evaluating how the individual technological operations of the rolling bearing ring production process affect the formation of their surface waviness. The surface waviness of the bearing race was measured in both directions (two sections), i.e., along the circumference using the Talyrond 365 measurement system and across the circumference of the race using Talysurf PGI. The production of 6308-2z rolling bearings made of AISI (American Iron and Steel Institute) 52100 bearing steel was analyzed. The occurrence of the phenomenon of technological heredity in the production of rolling bearings was observed. The research results indicate that the turning operation reduces the surface waviness of the bearing rings obtained after forging, while the heat treatment causes a slight increase in surface waviness. On the other hand, grinding operation significantly reduces the waviness, with this reduction being greater for the outer ring. Furthermore, the research has shown that the waviness of the surface is an inheritance factor caused by individual operations of the rolling bearing rings manufacturing process.

Analysis of Metrological Quality and Mechanical Properties of Models Manufactured with Photo-Curing PolyJet Matrix Technology for Medical Applications.

This paper presents the metrological quality and mechanical properties of models in the form of hook holders manufactured from MED610 polymer material using PolyJet Matrix (PJM) technology. Measurements in the dimensional and shape analysis were made using the optical method with a microscope. The mechanical test was estimated by static tensile testing of the fabricated parts. A comprehensive approach to both the analysis of test results based on standardized samples and real hook models makes the presented results of great scientific and engineering value and creates the possibility of practical use in the medical industry, which has not been so comprehensively presented in the currently published research papers. Analyzing the results of measurements of the geometrical characteristics of the elements, it can be concluded that the PolyJet Matrix 3D printing technology has demonstrated a high level of precision in manufacturing the prototype parts. The static tensile test of samples, taking into account the printing directions, showed a high anisotropy of mechanical properties. The results of both strength and simulation tests indicate that it is necessary to assume a relatively high safety factor, the value of which depends on the direction of printing, which, in the case of such a responsible medical application, is very important.

Multiscale Analysis of Surface Texture Quality of Models Manufactured by Laser Powder-Bed Fusion Technology and Machining from 316L Steel.

The paper presents the results of tests aimed at evaluating the surface textures of samples manufactured from material based on 316L stainless steel. The analysis of the surface topography was conducted based on the classical approach in accordance with the current standard and with the use of multiscale methods; i.e., wavelet transformation and geometric via curvature. Selective laser melting 3D printing technology was used to produce samples for surface testing. Furthermore, additional assessment of surfaces created as result of milling was conducted. Statistical research demonstrated a differentiation in the distribution of particular morphological features in certain ranges of the analyzed scales.

Morphology of Models Manufactured by SLM Technology and the Ti6Al4V Titanium Alloy Designed for Medical Applications.

This paper presents the results of an experimental study to evaluate the possibility of using SLM additive technology to produce structures with specific surface morphological features. Qualitative and quantitative tests were conducted on samples fabricated by 3D printing from titanium (Ti6Al4V)-powder-based material and analysed in direct relation to the possibility of their use in medicine for the construction of femoral stem and models with a specific degree of porosity predicted by process-control in the self-decision-making 3D printing machine. This paper presents the results of the study, limitations of the method, recommendations that should be used in the design of finished products, and design proposals to support the fabrication process of 3D printers. Furthermore, the study contains an evaluation of how the printing direction affects the formation of certain structures on the printed surface. The research can be used in the development of 3D printing standardization, particularly in the consideration of process control and surface control.

Quality of Surface Texture and Mechanical Properties of PLA and PA-Based Material Reinforced with Carbon Fibers Manufactured by FDM and CFF 3D Printing Technologies.

The paper presents the results of mechanical tests of models manufactured with two 3D printing technologies, FDM and CFF. Both technologies use PLA or PA-based materials reinforced with carbon fibers. The work includes both uniaxial tensile tests of the tested materials and metrological measurements of surfaces produced with two 3D printing technologies. The test results showed a significant influence of the type of technology on the strength of the models built and on the quality of the technological surface layer. After the analysis of the parameters of the primary profile, roughness and waviness, it can be clearly stated that the quality of the technological surface layer is much better for the models made with the CFF technology compared to the FDM technology. Furthermore, the tensile strength of the models manufactured of carbon fiber-enriched material is much higher for samples made with CFF technology compared to FDM.

Multi-Dimensional Mathematical Wear Models of Vibration Generated by Rolling Ball Bearings Made of AISI 52100 Bearing Steel.

The paper features the development of multi-dimensional mathematical models used for evaluating the impact of selected factors on the vibration generated by 6304ZZ type rolling ball bearings from three manufacturers in the aspect of the wear process. The bearings were manufactured of AISI 52100 bearing steel. The analyzed factors included the inner and outer raceways' roundness and waviness deviations, radial clearance and the total curvature ratio. The models were developed for vibration recorded in three frequency ranges: 50-300 Hz, 300-1800 Hz and 1800-10,000 Hz. The paper includes a specification of the principles of operation of innovative measuring systems intended for testing bearing vibration, raceway geometries and radial clearance. Furthermore, it features a specification of particular stages of the multi-dimensional mathematical models' development and verification. Testing with the purpose of statistical evaluation of the analyzed factors is also presented. The test results and mathematical models indicate that the inner raceway's waviness deviation had a dominant impact on the vibration examined in all frequencies. The roundness and waviness deviation of bearing raceways made of AISI 52100 steel propagates the bearing wear process.

Waviness of Freeform Surface Characterizations from Austenitic Stainless Steel (316L) Manufactured by 3D Printing-Selective Laser Melting (SLM) Technology.

The paper presents the results of tests of surface waviness of samples made in the powder bed fusion technology. The models were built using 316L steel-based powder with high corrosion resistance. The samples were placed on the construction platform at three different angles (0°, 45°, 90°) in XZ plane. Then, using an optical profilometer, the parameters of the geometric structure of the surface of the primary profile and the separated waviness component were measured. Analyzing the results of the test, it can be stated that the orientation of model arrangement has an impact on the quality of the technological surface texture, what has significance impact on wear processes and mechanical properties.