Jozef Živčák

MATERIAL AND THERMAL ANALYSIS OF LASER SINTERTED PRODUCTS

Abstract Thermal analysis of laser processes can be used to predict thermal stresses and consequently deformation in a completed part. Analysis of temperature is also the basic for feedback of laser processing parameters in manufacturing. The quality of laser sintered parts greatly depends on proper selection of the input processing parameters, material properties and support creation. In order to relatively big heat stress in the built part during sintering process, the thermal simulation and thermal analysis, which could help better understand and solve the issue of parts deformations is very important. Main aim of presented work is to prepare input parameters for thermal simulations by the use of RadTherm software (Thermoanalytics Inc., USA), directly during the sintering process and after the process and find out the impact of the heat stress on a final shape and size of the prototype. Subsequently, an annealing process of constructed products after DMLS could be simulated and specified.

Embedded Tensile Strenght Test Machine FM1000 – An Upgrade of Measurement and Control

In order to compare the strengths of various materials it is necessary to carry out a standard form of test to establish their relative properties. The tensile test, compression test, bending, shearing and torsion tests are used for examining mechanical properties of biological materials. Except for non-destructive methods (optical, electromagnetic, sonic, thermal, infrared), destructive testing is another very important tool for the assessment of biomechanical properties and behavior of biomedical materials. The tensile strength test is one of the most common testing methods, which uses specific testing machines. Many tensile testing machines are equipped to plot a curve which shows the load or stress and the strain or movement that occurs during the test operation. In the testing operation, the load is increased gradually and the specimen will stretch or elongate in proportion to the tensile load. The load cells and extensometers measure the key parameters of force and deformation. The presented paper is a report which describes a specific and unique technical solution and upgrade of FM 1000 machine from the control and output processing point of view. Modern sensoric systems and I/O modules were used and custom software was developed. The fu

Application of Magnetic Microwires in Titanium Implants - Conception of Intelligent Sensoric Implant

The idea of intelligent sensoric implant which enables to scan parameters from the human body wireless comes from analysis of studies descrbing reasons of implants rejection or loosening. Inflamations and incorrect biomechanical load are offen the reasons for surgery, where implant has to be removed or replaced. Presented study shows a concept of intelligent dental implant, where magnetic microwires are placed and fixed into titanium dental implant to get parameters from implant, tissue, or implant-tissue interaction. A part of the study shows preparation of magnetic microwires, measurement of physical quantities using bistabile magnetic microwires and realisation of the functional model of the sensor and experiments. Obtained results show, that utilization of magnetic microwires in implants for scanning of selected physiological or physical parameters is promising. The further researches in the field of fabrication technology, magnetic wires preparation and scanning processes to confirm an intelligent sensoric implant concept is necessary.

Usage of Industrial Computed Tomography for Evaluation of Custom-Made Implants

Development of additive technologies and biocompatible materials facilitated their use in the custom-made implants manufacture. Verification of custom-made implants manufactured using the additive manufacturing technologies is the key task to be fulfilled prior to the clinical application of an implant. It consists of parameters verification within individual steps, from a software design, through manufacturing, surface finishing, up to finalization of a medical product. The article presents possible uses of a 3D printing and the computed tomography (Metrotom 1500, Carl Zeiss, Germany) for the verification of selected parameters of customized implants manufactured using the Direct Metal Laser Sintering (DMLS) technology with the EOSINT M280 equipment (EOS GmbH, Germany) from the biocompatible titanium alloy Ti-6Al-4V (Grade 5). The article describes the possibilities of the computed tomography use in the verification of implant shapes and external dimensions, as well as internal structure. The internal structure means the implant porosity assessment.

Implantation of a 3D-printed titanium sternum in a patient with a sternal tumor

BackgroundPrimary malignant or metastatic sternal tumors are uncommon. A subtotal or total sternectomy can offer a radical form of treatment. The issue is to restore the structural integrity of the chest wall.Case presentationWe report the implantation of an individualized 3D–printed titanium sternum in a patient with a sternal tumor.ConclusionsWe believe that tridimensional print technologies may also change the strategy of chest wall reconstruction.

Biomedical Applications of Diagnostics and Measurements by Industrial Computer Tomography

The aim of presented study is a review on biomedical applications of industrial computed tomography (CT). Industrial CT enables in contrast to medical CT scanning of technical materials (plastic materials, low density metals, wood, etc.) but also living tissues in vitro. Important parameters for scanning are maximum size of the part 300 x 300 x 300 mm; and the best obtainable resolution of the digitalized scan is 9 μm. The termination for the scanning is also density of material, where low density medical materials like titanium or medical polymers are applicable. Presented review shows potentials of industrial CT for biomedical applications; an assembly inspection, damage analysis, inspection of materials, porosity analyses, conventional defect, and the reverse engineering.

Method for Measurement of Residual Stresses using Eddy Currents

Article is focused on using eddy current to measure of internal residual stress after milling. In presented article is described methodical process of identification residual stress in internal layers of the surface after machining of steel C45. Eddy current provides fast identification of residual stress directly in engineering areas without necessity to transfer samples in specialized laboratories. Presented article also describe procedure of evaluating measured values of deviation and its transformation to values of residual stress by conversion coefficients.

A Comparison of Mechanical Properties of Lumbar Bilateral Implants Manufactured by Additive and Conventional Technologies

Spinal implants are mechanical equipments that facilitate fusion, correct deformities, and stabilize and strengthen the spine. To make an implant efficient, it has to endure without any failure, especially mechanical damage, stand all the static and dynamic loads incurred in spine during everyday activities, and maintain the necessary position of motive segments during the bone adhesion. [1] Human spine is exposed to the highest load in the lumbar section [2]; therefore, lumbar bilateral implants require higher attention in terms of mechanical parameters verification. The main objective of this paper was to compare mechanical properties of lumbar bilateral systems using the spinal implants manufactured by the conventional method and the Direct Metal Laser Sintering method (DMLS). Detection of mechanical properties enables the assessment of possible replacement of commercial manufacture with the DMLS manufacture. On the basis of the ASTM F1717 standards providing the essentials for the comparison of mechanical properties of spinal systems, twenty mechanical compression tests were carried out. Mechanical tests were carried out using 20 spinal bars with the diameter of 11 mm and the fastening length of 260 mm, manufactured by the DMLS technology while using the EOSINT M280 equipment (EOS, Germany), and 20 identical spinal bars manufactured by the conventional technology. Results obtained in mechanical compression tests indicate that both manufacture methods are comparable and there are no significant differences between them, as for the strength characteristics. Other trials will be focused on static tensile tests and cyclical tests of lumbar bilateral systems.

Influences of Surface Determination for Measurements Obtained by Industrial Computed Tomography

At present emphasis is placed on input or output control of products in the manufacturing process. One of the criteria is the dimensional analysis or porosity analysis of products. In the case that products are of complicated shapes, or measurements are to be taken in places which are not accessible to standard measuring devices (manual measurements, coordinate measuring machines) the use of computed tomography is one of the possibilities for obtaining the desired dimensions. These technologies work with digital data and therefore the surfaces which are to be assessed must be created on the basis of determined criteria. Surface determination is one of the most important settings during the evaluation of the visual shape (state) of a surface and assessing dimensions. During such evaluation this is the main parameter which globally influences the precision of the obtained data. In the case of an unsuitably determined surface the obtained results can vary from reality even by several tenths of a millimeter depending on the scanned object and the scanning conditions. The conveyor belts are composed of two or more materials with different densities, such as rubber and textile fibers. In cooperation with Faculty of Mining, Ecology, Process Control and Geotechnology is tested and evaluated the effect of the impactor with various energy into conveyor belt. The correct surface determination for selected material is necessary to evaluate the dimensions, the damage and pores. The article deals with the impact of surface determination on the result of a measurement.

Applications of Metrotomography in Biomedical Engineering

More than one hundred years ago X-ray technology started its triumphal procession when Wilhelm Conrad Roentgen discovered a new kind of radiation in his laboratory in Wuerzburg, Germany in the year 1895. Up to this moment most of the developments in Xray technologies and computed tomography have been focused on special medical applications. Eighty years later computer tomography (CT) was first tested, and it has since become a powerful tool well-accepted in industrial applications. Today industrial CT is central to innovations in material testing and geometry analysis, and to the development of high-tech quality-control devices and industrial and medical tools [13].