Search

The total machining error includes some distinct errors summed up by following certain rules. One of these errors is the workpiece locating error, which occurs when the workpiece reference base does not match the workpiece locating surface. The paper analyses different definitions of positioning error, as they were proposed by different researchers or groups of researchers and presents an application valid in the case of turning a cylindrical workpiece with locating between the centers. A definition of locating error that takes into account the total differential of the size of the vector that joins the orientation surface with an element of the fixture was preferred. A fixture version was considered to ensure the locating and clamping of the workpiece on the lathes, with workpiece locating between the centers. This fixture uses a mandrel with a sliding center and an elastic collet.

Over the years, the importance of the creativity inclusively in the field of design activities was highlighted. In accordance with the opinions of certain researchers, the divergent thinking could contribute to the increase of creative processes efficiency. On the other hand, the axiomatic design method is considered as a method able to stimulate the technical creativity when the problem of designing a mechanical equipment is stated. To increase the efficiency of using the axiomatic design method, the possibility of selecting the most convenient solution among many available solutions could be discussed. The analysis revealed that there are many methods that could be applied in the process of optimum solution selection among many available solutions. In this paper, some aspects concerning the possibilities of using the method of analytic hierarchy process are analyzed, inclusively by considering a case study concerning a device for investigating the universal horizontal lathe rigidity. Afterwards, the first axiom from axiomatic design method was applied to define the selected solution for the approached device.

In the paper, the problem of obtaining small diameter holes in workpieces made of high speed steel by electrical discharge machining was formulated. A fulfil factorial experiment was designed and materialized, taking into consideration the tool electrode diameter, pulse on time and pulse off time as independent variables. The tool electrode wear was evaluated by means of the decrease of tool electrode mass and length. On the base of experimental results, power type empirical mathematical models were determined. One noticed the higher influence exerted by the too electrode diameter, whose increase determine the decrease of the tool electrode.

The development of mathematical models by using experimental data is of great importance for modelling and optimization of the laser cutting process. Motivated by the lack of research regarding the use of genetic programming (GP) for deriving empirical mathematical models that describe the laser cutting process, the present study discusses the application of GP to the development of a kerf taper angle mathematical model. The aim was to quantify the relationship between three selected input parameters (cutting speed, laser power and assist gas pressure) and kerf taper angle using GP in the CO2 laser cutting of aluminium alloy AlMg3. To obtain the experimental database for the GP model evolution process, a laser cutting experiment was planned as per standard full factorial design where all three selected parameters were varied at three levels. The fit between the experimental and the GP model prediction values of kerf taper angle was found to be appropriate. Finally, by using the derived GP mathematical model, the analysis of the effects of input parameters on the change in kerf taper angle values was performed by generating 3D surface plots. [ABSTRACT FROM AUTHOR]

Waviness is a parameter used to complete information on the machined surface state. There is little scientific and technical information on the influence exerted by the cutting conditions and the workpiece material hardness on the values of some parameters that define the waviness of milled surface. No works have been identified to present such information for dry high-speed face milling applied to hard steel workpieces. A factorial experiment with four independent variables at three variation levels was planned to model the influence of milling speed, feed, cutting depth, and steel hardness on the total heights of the profile and surface waviness for dry high-speed face milling. Mathematical processing of experimental results was used to identify the power type function and empirical mathematical models. These models highlight the direction of variation and the intensity of influence exerted by the considered input factors on the values of two waviness parameters in the case of dry high-speed face milling of samples made of four hard steels. It has been observed that the increase in steel hardness increases the total heights of the profile and surface waviness. In the case of two types of steel, a good correlation was identified between the values of the total profile waviness height and the total surface waviness height, respectively, using the Pearson correlation coefficient. [ABSTRACT FROM AUTHOR]

Rectilinear kerfs in workpieces made of hard electroconductive materials can be made by wire erosion electrical discharge machining. However, since machine tools intended for such machining are rarer and more expensive, the problem of using devices for wire electrical discharge machining, but adaptable to ram electrical discharge machines, has been formulated. The identification of the functional requirements for such a device in accordance with the principles of axiomatic design led to the defining of a device solution flexible enough to be able to be adapted to different machining conditions. In the constructive solution of the device were incorporated subsystems for pulling and guiding the wire electrode, for changing the angular position of the wire electrode in the machining. The realization and preliminary experimentation of the device led to the formulation of some suggestions for improving the constructive solution of the device. [ABSTRACT FROM AUTHOR]

Electrochemical engraving is a process that allows the making of various inscriptions on the surfaces of parts of electroconductive materials. The removal of material from the workpiece occurs due to chemical reactions developed between the workpiece material and an electrolyte in the presence of a direct electric current. Many factors can affect the values of the output parameters of the electrochemical engraving process. The main groups of factors capable of influencing the output parameters of the electrochemical engraving process are the nature and chemical composition of the workpiece material, the shape and arrangement of the workpiece surface to the cathode, some physical and chemical properties of the electrolyte, the shape and the arrangements of the cathode surfaces, duration of the engraving process, etc. Some functional equipment requirements intended to develop experimental research of the process were first formulated to assess the influence exerted by some of the input factors in the engraving process. A test piece and simple equipment designed to meet the functional requirements under consideration were then considered. A planned factorial experiment was designed to highlight the influence of input factors on characteristics that define the results of electrochemical engraving. Empirical mathematical models were generated by the mathematical processing of the experimental result for the modification during the electrochemical processing of some of the test piece zones. These empirical mathematical models provide information on the intensity of the electrochemical processing in different areas of the test piece. Power-type mathematical functions were used for this purpose. The electrolyte concentration, the intensity of the electric current flowing between the electrodes, and the duration of the processing were taken as independent variables. [ABSTRACT FROM AUTHOR]

Punching is a cold deformation process by which holes are obtained in the workpiece in sheets or plates. The part of interest is the separate part of the workpiece or that which remains after separating an area from the plate or sheet. A systemic analysis of the punching process was first performed to investigate the punching processes better. The analysis revealed the parameters of interest in the case of such processes and the factors that influence the values of the parameters of interest. The use of the first axiom in the axiomatic design facilitated the identification of some components of a device that would fulfill the different functional requirements of the device. A variant of the device was designed to facilitate a more detailed study of the material's behavior in the area affected by the plastic deformation process. The device considers the specific components of a die, being adaptable to some of the existing universal machine tools in a mechanical workshop. [ABSTRACT FROM AUTHOR]

The electrical discharge machining is a machining method applied when the workpiece material has a high hardness or the shape of the surface to be machined is to complicate to be obtained by a classical machining method. A problem of actual interest is the electrical discharge machining of small diameter external cylindrical surfaces in the case of materials characterized by high hardness. Among the distinct electrical discharge machining processes capable to be used in order to obtain small diameter cylindrical surfaces, a process based on the use of a plate type tool electrode was selected. A full factorial experiment with three independent variables and two experimental levels was designed and materialized to highlight the influence exerted by the pulse on time, pulse off time and peak current intensity on the heights of the cylindrical columns generated by electrical discharge machining. By mathematical processing of the experimental results, power type empirical mathematical models were established. The empirical models confirmed the strong influence exerted by the peak current intensity on the process output parameter. [ABSTRACT FROM AUTHOR]

The magnetic abrasive machining is a machining method based on the use of the magnetic field to generate a flexible abrasive brush from abrasive and/or ferromagnetic particles. The possibility of obtaining low values for the Ra surface roughness parameter led to the use of this machining method, especially as an abrasive finishing method. Over the time, various versions of machining techniques were proposed and some of them were in detail investigated and applied in industry. When the problem of selection or application of a certain magnetic abrasive machining technique is formulated, information concerning the magnetic abrasive machining methods and techniques and their characteristics could be necessary. The documentary research activity allowed to the authors of this paper elaboration of a review on the magnetic abrasive machining/finishing, by taking into considerations information found in the accessible specialty literature. As a result, a synthetic presentation concerning some machining/finishing magnetic abrasive techniques, principles of this machining method, its applications and major research areas was elaborated. KEYWORDS: magnetic abrasive machining, finishing, work principle, applications, research areas. [ABSTRACT FROM AUTHOR]