Abstract: The article is focused on the aspects in samples production of sophisticated material – PLA - PolyLacticAcid, PLA plastic. The main part of the work focuses on experimental production and testing of PLA material - PolyLacticAcid plastic, printed on RepRap 3D device that works on the "open source" principle. The article presents the outcomes of test materials in the form of measurement protocols recorded in the software, the measured values in a static tensile test, marked down in tables and shown in work graphs. The article describes selected and carried out tests of mechanical properties of PLA plastics extruded in different directions in this case carried out vertically by FDM rapid prototyping method of two PLA materials such as pure without additives blended with blue dye. The tests are mainly focused on the determination of ultimate tensile strength. Based on the results obtained, the samples made of two PLA materials were compared in the end to establish which produced PLA material sample is stronger. There are outputs in the form of logs, charts and tables that provide information about the executed tests and comparisons, which were made by the authors.
Abstract: The article focuses on the samples production of organic material PLA-PolyLacticAcid – bioplastic. The main part describes the experimental testing of PolyLacticAcid plastic and sample production by Fused Deposition Modeling, Rapid Prototyping technology. The article presents selected carried out tests of mechanical properties focused mainly on the determination of ultimate tensile strength of two PLA-BIO plastic extruded horizontally along the width produced by FDM method, Rapid Prototyping. The authors of this article present their results of test materials in the form of measurement protocols recorded in software, the measured values in a static tensile test, recorded in tables and shown in work graphs. Based on the results of the two samples produced from PLA biomaterials and compared to determine which PLA – bioplastic is stronger.
Abstract: The paper describes the basic physical regularities of material removal in Electrical discharge machining (EDM) of tool steel. One of the parameters, that material removal regularities quite accurately identifies, is the tool wear rate (TWR). This parameter, however, describes only the regularities concerning the tool electrode wear. More complex parameter for assessing regularities of material removal in EDM is thus electrode wear ratio (EWR). This parameter, except the size of the wear of the tool electrode, also describes the size of the workpiece material removal. Research on material removal was carried out on samples made out of tool steel EN X32CrMoV12-28 using Cu-ETP electrode EN CW004A. Aim of this paper was also based on the selection of main process parameters that significantly influence the material removal in EDM to define the individual specifics with regard to minimizing EWR.
Abstract: Geometrical precision machined surface is generally understood as mainly precision shape, orientation, location and run-out. As a rule, it is measuring the appropriate deviations from the nominal surface. The geometric size of this deviation from the nominal surface can in practice affect the conventionally measured value for the dimension and the dimension whilst maintaining the required tolerance. Because the WEDM technology is among the most accurate technology, the small final geometric accuracy deviation has also a negative impact on the final quality of the machined surface. The paper aimed to describe errors geometrical precision of machined surface which occurs in wire electrical discharge machining (WEDM) and quantify their scope.
Abstract: When processing materials using the milling technology, regenerative fluctuations of vibrations are the decisive factors, which limit productivity. In some case the size of the vibrations can cause shortened lifespan of the tool, decrease reliability and operational condition of the device, and subsequently case poor quality of the processed surface. Predicting the size of the vibrations between the milling machine and the work-piece is important as a lead for the users of the tool to select optimum depth of the cut and turning of the spindle, which leads to maximum rate of splinter removal. The extent of the research is focused especially on the process of monitoring, with the goal to analyze the size of the vibration at three places determined in advance - spindle head, work-piece and support, where rotation speed of the spindle change during the processing, as well as rate of splinter removal. By evaluating the results of experimental research, it is possible to determine adequate rotation speed of the spindle and depth of the cut, to achieve longest lifespan of the machine.
Abstract: The paper deals with the wear of tool electrodes for Die Sinking EDM. In the experiment were used the electrodes of copper and graphite. The workpiece material was steel EN43CrMo4. For the assessment the effects of each parameter was used the statistical method Design of Experiments (DOE). Assessed input factors were the peak current, pulse on-time, pulse off-time, and the electrode material. The result of the effects of each input factors was tool electrode wear. For calculating the relative wear of electrodes was used the percentage of the ratio of the electrode and the workpiece weight. The results show that the expression of the relative wear in practice can be described as a method unusable due to the absorption of the graphite electrode used in the experiment.
Abstract: The quality of thin wall castings produced by metal die-casting depends on the coherence and consistency of various aspects influencing the process of casting cycle. The qualitative properties of castings should already be considered in the design phase of construction of the gating system. The simulation software is an effective facility for the initial revealing of defects of the design phase. The assessment of casting cycle by the means of simulation predicts an incidence of defects of the casting core in the design phase and therefore reduces both the incidence of defects in the production and the costs while the production efficiency is increased. The article deals with the assessment of the design of the gating system for a particular casting type. The filling of mould cavity, casting solidification and time course of temperature changes occurring in the selected locations of gating system were defined as parameters indicating the assumptions of design accuracy. Simulation tests were carried out in the NovaFlow&Solid program. The tests resulted in a conclusion evaluating and describing the adequacy of structural design of the gating system.
Abstract: From the point of view of its design solution, the shape, the dimensions and the position of an gate have the biggest impact on the final quality of castings. The gate is where the stream of hot-melt flowing into the mould cavity is modulated, and where the speed of this stream changes, which eventually determines the loading mode of the mould cavity affecting the homogeneity of any casting, and thus its mechanical properties as well. The length of the gate for a specific type of casting is determined constantly according to the projection methodology for connecting the gate to the casting. The gate height is determined by its area to length ratio. In practice, several methods are used to determine the gate area. The presented paper deals with an assessment of particular methods of designing the gate area for a specific type of a lightweight casting on the basis of silumin produced, using die casting technology. Since the length of the gate is constant, based on particular methods for determining the area, the gate height is the variable parameter. The performed experiments focus on an assessment of permanent deformation of parts cast at certain gate heights, determined analytically according to particular calculation methods. Permanent deformation serves as an indicator of the most suitable method for the gate area calculation. At the same time, the paper specifies patterns required for the calculation of gate dimensional characteristics, since the available scientific literature only provides indicative values depending on the nature of any given casting or an alloy.
Abstract: For a regulation of moulding cooling time course in a mould it is necessary to derive an equation of the mould temperature dependence on the moulding temperature as the equation of the regulation system. Amplitude, phase and transition characteristic are for R=1 and P=1 identical as for the action quantity. Amplitude, phase and transition characteristic of the action quantity and the control of the regulation circuit at use of the proportional regulator show that the circuit is stable a periodic. From the amplitude, phase and transition characteristic of the regulation circuit defect it is seen that the defect in the regulation circuit is relatively fast lowered.
From the mentioned conclusions it is seen that the moulding cooling in the mould at injection of plastics with the proportional regulator introduces the regulation with relatively favourable regulation properties.
Abstract: When creating products of modern construction materials has a great influence on their endpoints right way and the quality of working on machine tools. The article deals with positioning accuracy of machine tools which is carried out in an unloaded condition, according to international standard ISO 230-2. Overall accuracy of working machining is determined mainly static rigidity, geometrical accuracy of mechanical components, positioning accuracy and dynamic stiffness. Static stiffness is defined in new machine tools in a limited workspace. Therefore, the article deals with the definition of static stiffness in the expanded work area and also defines its impact on the positioning accuracy at individual points in workspace of the machine tool.