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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]

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]

Distinct cutting methods could be applied to separate parts from a plate workpiece. Now-a-days, among such methods, the thermal plasma allows obtaining a relatively narrow slot, a high cutting speed and a cut surface appreciated as acceptable in certain situations. Essentially, the thermal plasma is generated by sending a gas through the electric discharge developed between the central electrode and the nozzle, as components of the plasma generator. The analysis of plasma cutting process showed that there are some groups of actors able to affect the heights of asperities generated by the cutting process on the cut surface. A full factorial experiment with three independent variables at two levels was designed and achieved by considering some of process input factors whose values could be easier modified, to investigate their influence on the value of the Ra surface roughness parameter. By processing the experimental results, a power type function was determined. The analysis of this empirical mathematical model and of the elaborated graphical representations highlighted the influence exerted by the cutting speed, plate workpiece thickness and current intensity on the Ra surface roughness parameter. [ABSTRACT FROM AUTHOR]

There are situations when for distinct reasons, a process of threading by electrical discharge machining has to be applied. In order to materialize an electrical discharge threading process, an analysis of the information available in the specialty literature and in industrial practice was developed. The analysis revealed the possibility to design a device for electrical discharge threading adapted on a ram electrical discharge machine. On this base, a device including a ball screw and a gear mechanism was designed. The device transforms the rectilinear work motion of the machine tool head into a rotation motion and a rectilinear feed of the tool electrode. [ABSTRACT FROM AUTHOR]

The electrochemical machining with forced hydrodynamic depassivation allows the material removal from workpiece by electrochemical erosion. The products resulted as a consequence of the electrochemical reactions developed between the workpiece material and electrolyte are removed from the machining zone by forced circulation of the electrolyte. A theoretical analysis led to formulation of several hypothesis concerning the behaviour of some metallic materials when test samples presenting a conical surface are affected by the electrochemical machining process with forced hydrodynamic depassivation. In the paper, the results of some experimental researches developed on test samples from steel, bronze and aluminium are presented. By mathematical processing of the experimental results, some empirical mathematical models were established. The empirical models highlight the influence exerted by the gap size, by the size of angle corresponding to the conical surface and by the voltage applied to the two electrodes on the size of the final gap and on the quantity of material removed from the test piece, for a certain duration of the machining process. [ABSTRACT FROM AUTHOR]

In a world where minimizing tendency is everywhere, the necessity of obtaining surfaces of small dimensions, but with similar properties and reliability as those with regular dimensions is evident. Electrical discharge machining of small diameter external cylindrical surfaces meets the minimizing tendency in industry and offers a series of outstanding advantages comparing to classical machining methods. Applying a machining pattern that uses a plate electrode having 8 sets of holes with 4 distinct diameters each, experimental tests had been done, in order to analyze and model the evolution of tool electrode wear. The wear of the tool electrode is the result of the machining process and it can be both controlled and estimated using input parameters. In this paper, a series of parameters with impact on tool electrode wear is analyzed and empirical mathematic models were determined in order to highlight certain process input factors influence on tool electrode wear degree. [ABSTRACT FROM AUTHOR]

The electrical discharge drilling could be applied in order to obtain cavities in workpieces made of materials difficult to be machined by classical machining methods. Distinct factors exert influence on the drilling speed. An experimental research was designed and developed by considering the depth of the cavity achieved by means of a tubular tool electrode. One used a machining scheme involving the achieving of the work movement by test piece to the tubular tool electrode clamped on the machine tool table. In this way, the influence exerted by the spurious electrical discharges facilitated by the presence in the work gap of the metallic particles detached from the two electrodes can be diminished. Empirical mathematical models were determined by mathematical processing of the experimental results and using specialized software. The empirical mathematical models proved a high influence exerted on the drilling speed by the peak current intensity. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is one of the most used non-traditional machining processes. In order to detach and remove the material from the workpiece surfaces, the process uses thermoelectric energy that allows the development of electrical discharges between the workpiece and a tool electrode that are positioned in a dielectric environment. The major advantages of this machining process are reflected in its capability to cut precisely, geometrically complex material regardless hardness. Electrical discharge machining can be applied to obtain cylindrical parts from a workpiece made of an electroconductive material. The paper presents the results of an investigation concerning the effect of some machining factors on the material removal rate (MRR) in electrical discharge machining (EDM) of small cylindrical surfaces. [ABSTRACT FROM AUTHOR]