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There are different types of bushings used in mechanical equipment and they can be used for different purposes. In the case of bronze bushings used to ensure rotation conditions of shaft-type parts, there are some difficulties in addressing the problem of their manufacture. In essence, in order to meet the machining accuracy requirements specific to the outer and inner revolution surfaces, appropriate manufacturing technologies must be established. Some distinct technological paths can be considered for machining and checking the outer and inner cylindrical surfaces of bushings. In solving certain problems specific to the development of bushing manufacturing technologies, the principles of axiomatic design were used. Thus, the axiom of the independence of the functional requirements was used preferentially in establishing the machining operations to be applied to the workpieceto obtain a bushing. The second axiom was applied to identify the best solutions for the machining of the inner revolution surface. In this way, more convenient manufacturing technology for bronze bushings was identified.

The last decades highlighted the necessity of obtaining surfaces of small dimensions in case of some complex parts or workpieces made of materials difficult to be cut by classical machining methods. In such cases, one of the machining methods able to facilitate the obtaining of surfaces of small dimensions is the electrical discharge machining. The purpose followed by research whose results are presented in this paper was to identify a solution for a pulse generator which could be incorporated and used in equipment for electrical discharge machining of surfaces of small dimensions. The analysis of microelectrical discharge machining process showed the conditions necessary to be fulfilled by the pulse generator. The experience of researchers who built electrical discharge equipment was taken into consideration. In order to limit the heat dissipation and energy waste on resistors and semiconductors, a subsystem based on the use of transistors characterized by high speed switching was applied within an independent pulse generator. In order to obtain a high quality of the small dimensions machined surfaces, a relaxation-type pulse generator was included in equipment for electrical discharge machining. An intelligent control unit was used, in order to ensure possibilities of changing the characteristics of machining pulses, in accordance with the conditions from work gap. The preliminary experiments proved the good functioning of the pulse generator and the possibilities to obtain surfaces of small dimensions on the proposed equipment.

The paper deals with the investigations of influence parameters of electro discharge machining (EDM) on the shape accuracy of external cylindrical surfaces machined by EDM process. A Sodick AD3L CNC electrode discharge machine was used to perform the EDM tests. In order to obtain the external cylindrical surfaces by RAM EDM copper cylindrical electrodes were used. Different machining setups and dielectric immersion modes were considered. In order to investigate the influence of the machining parameters on the investigated factors a factorial plan of experiments was considered. The preliminary experimental results highlighted the possibilities to obtain small diameter external surfaces of revolution on a ram electrical discharge machine.

The goal of this paper is to show that one can teach mechanical design making the students aware about the sustainability issues in mechanical engineering by incorporating obsolete parts. The example herein developed aims at finding viable design solutions by re-using end-of-life components to perform functions that are very similar to the ones for which they were initially designed, with only minor adjustments to make them suitable for their new purposes. A Savonius wind turbine was chosen for our exercise since it is easy to build and assemble, has low manufacturing costs and is appropriate for delivering a small amount of mechanical power.

Wire electrical discharge machining is nowadays applied by using adequate specialized machine tools. A research problem could refer to a device for wire electrical discharge machining, adaptable on the current computer numerical controlled ram electrical discharge machines. The device could be able to be used in order to develop cutting processes in plate type workpieces. The wire electrical discharge machining process was examined and premises for developing a device for wire electrical discharge machining were formulated. These premises are used in order to develop an ideas diagram able to offer suggestions for the structure of the device. Distinct components necessary in the device structure were identified and taken into consideration, and three distinct versions of the device were defined.

The wire electrical discharge machining is a machining method able to allow detaching parts from plates type workpieces as a consequence of electrical discharges developed between workpiece and wire tool electrode found in a motion along its axis; there is also a work motion along the contour to be obtained. There are many factors able to exert influence on the sizes of parameters of technological interest. On the other hand, there are various methods that can be used in order to establish the optimal combination of the input factors, so that obtaining of machining best results is possible. When there are many process output factors, a problem of multiobjective optimization could be formulated. The Grey relational analysis method and the Taguchi method could be applied in order to optimize the wire electrical discharge machining process, when various criteria having distinct significances are considered. An experimental research was designed and developed in order to optimize the wire electrical discharge cutting of parts made of an alloyed steel, by considering six input factors: test piece thickness, pulse on time, pulse off time, wire axial tensile, current intensity and travelling wire electrode speed. As output parameters, one took into consideration surface roughness, wire tool electrode massic wear, cutting speed along the contour to be obtained. 16 experiments were developed in accordance with the requirements specific to a Taguchi table L16. The results of experiments were processed by means of Grey relational analysis method and Taguchi method.

The laser beam drilling is generally included in the larger group of laser beam machining methods based on the material removal. The problem addressed in this paper referred to the laser beam drilling of test pieces made of Plexiglas. Some theoretical aspects were highlighted by analyzing the physical effects developed in Plexiglas by the laser beam action. Experimental research was developed in order to highlight the influence exerted by the duration of the CO2 laser beam action on the Plexiglas in obtaining blind and through-holes. Empirical mathematical models and graphical representations allowed formulation of some remarks concerning the results of experimental research.

There are various factors able to exert influence on the results of electrical discharge machining process. If there are many output factors of the machining process, one can formulate a problem of multicriterial optimization. It is necessary to find adequate values for the input factors so that the output factors have optimized values. The paper presents the results of a research aiming to optimize the material removal rate and the tool electrode wear rate, in the case of ram electrical discharge machining process. As input factors, one used the pulse on time, pulse off time and average peak current intensity. The Taguchi method was applied, in association with the Grey relational analysis. In this way, combinations of values corresponding to the input factors were determined, in order to obtain optimal results for the process output factors.

The analysis of the drilling process addressed in this paper aims highlighting the factors able to exert influence on parameters of technological interest corresponding to such a process. There were applied the method of systemic analysis, Ishikawa diagram, SWOT analysis. The significance of the drilling tool active zone geometry within the drilling process and, in the tests for evaluation of the machinability by drilling was emphasized. With this aim in view, preliminary tests of using a specialized equipment for sharpening the small diameter drills were initiated.

Wire electrical discharge machining is a machining method by which parts having various contours could be detached from plate workpieces. The method uses the electrical discharges developed between the workpiece and the wire tool electrode found in an axial motion, when in the work zone a dielectric fluid is recirculated. In order to highlight the influence exerted by some input process factors on the surface roughness parameter Ra in case of a workpiece made of an alloyed steel, a factorial experiment with six independent variables at two variation levels was designed and materialized. As input factors, one used the workpiece thickness, pulse on time, pulse off-time, wire axial tensile force, current intensity average amplitude defined by setting button position and travelling wire electrode speed. By mathematical processing of the experimental results, empirical models were established. Om the base of a power type empirical model, graphical representations aiming to highlight the influence of some input factors on the surface roughness parameter Ra were achieved. The power type empirical model facilitated establishing of order of factors able to exert influence on the surface roughness parameter Ra at wire electrical discharge machining.

There are various electrical discharge machining techniques and experimental researches could be necessary in order to establish the operating conditions for an optimal machining process. Some theoretical considerations concerning the process of generating the surface asperities as a consequence of the electrical discharge machining process were elaborated. Experimental method was applied in order to evaluate influence exerted by some input factors (pulse on time, pulse off time, average intensity of electric current) on certain surface roughness parameters (Ra, Rz, Ry and Rq). One developed an experimental research by using a copper tool electrode and a workpiece made of high speed steel, in accordance with the requirements specific to a complete factorial experiment with three independent variables at three levels. A ram electrical discharge machine was used as machining equipment. One measured the surface roughness parameters specific to the machined surfaces. Empirical mathematical models of type power functions were established by using the method of least squares.

Electrical discharge machining uses the pulse electrical discharges generated between the closest asperities existing on the workpiece surface and the active surface of the tool electrode in dielectric fluid. Essentially, some distinct electrical discharge machining schemas could be used in order to obtain cylindrical external surfaces; within this research, one preferred a machining schema based on the use of a cooper plate in which there were small diameter holes, by taking into consideration the existence of a ram electrical discharge machine. The results of the machining process analysis were presented. A thin copper was considered to be used as tool electrode, in order to diminish the spurious electrical discharges, able to generate shape errors of the machined surface. Some experimental researches were developed by changing the sizes of the process input parameters. As output factors, the test piece and tool electrode masses decreases were considered. Power type empirical mathematical models were determined, in order to highlight the influence exerted by the pulse on time, off time and machining process duration on the output parameters values.

ProblemThe whirling cutting is considered as the most productive method of manufacturing the worm gearing. In the case of up cutting manufacturing, where the tool and the worm gearing are spinning in the cutting area in the same direction, the thickness of the chips is increasing from the value zero to the maximum value, with a significant gradient. This fact has a negative effect on the tool face of the cutting tool, because it generates an accelerated wearing of this face, despite the major wear is on the side face of the tool. It is important to discover the influence of the parameters of the tool in the whirling cutting process.MethodThe precision parameters which were measured at the manufactured worm gearing were the tooth radial run out, frr, the error from the constancy of the worm pitch, fpxr, the profile error, fflr, and the minimal error of the thickness of the worm gearing thread, Ess.ResultsThe thickness of the manufactured tooth depends on the precision of settling the cutting depth that is, on its turn, dependent of the precision of the lathe carrier positioning in the transversal direction. It is hard to obtain a perfect settling of the initial cutting depth by using the method of first touch the cutting edges that are rotating continuously with the piece.

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.

The laser beam machining uses the effects generated at the impact of the workpiece surface with a laser beam that has adequate energetically and spatial - temporal characteristics. It is known that, as result of the laser beam impact with the workpiece material, local chemical and physical effects are signalized. In order to study such effects and simultaneously the technological possibilities of laser beam equipment, some experimental researches were developed on an Ytterbium fiber laser equipment of 300 W. Movements of the laser spot along established trajectories were ensured, changing the sizes of the machining parameters. The influence exerted by the machining parameters and by the materials characteristics on the material removal from the test piece was highlighted. The surface layer modifications were also studied.

The laser beam machining is essentially based on the effects generated at the contact of the workpiece surface with a laser beam that has adequate energetically and spatial -temporal characteristics and is directed and focused or defocused by means of the optical lens and mirrors system. The paper presents some authors considerations concerning the possibilities to classify and analyze the laser beam machining by taking into consideration the thermal effect. Thus, if only the thermal effect is considered for a certain given laser beam machining equipment, the fundamentals of different machining techniques applicable on this equipment depends essentially on the energy density in the contact zone between the laser beam and the workpiece surface layer and on the duration of the contact between the laser beam and the workpiece. These aspects were analyzed in the case of laser beam machining equipment having an output power of 300 W and a numerical controlled table. The experimental research was developed to highlight the possibilities to materialize different machining techniques based on the thermal effect of the laser beam.

The material removal within different machining processes can be performed in distinct modalities. One of these modalities is based on the effects of certain impact phenomena. The objective of the paper was to find a modality to classify the non-traditional machining methods based on the impact phenomena and to emphasize some of their common and different characteristics. The research was performed by taking into consideration the information included in the specialty literature and the authors experience. The conclusion is that a systematic study could offer an integrating image concerning the main aspects specific to the non-traditional machining processes based on impact phenomena. The main ways for the material removal as consequence of the impact phenomena are the microcracking, microcutting, melting and vaporizing of small quantities from the workpiece surface layer.

One of the activities corresponding to the product design and development refers to clarifying the requirements necessary to be fulfilled by the final product. There are distinct opinions concerning the ways in which these requirements could be formulated and applied. The paper presents the results of a succinct analysis aiming to highlight the developing of product requirements in the case of applying the value analysis method and the axiomatic design method, respectively. The way in which the requirements are formulated in the case of a patent application is also considered. Results of the study were applied in the cases of designing some mechanical products.

In the case of the electrical discharge machining, the obtained surface is a concatenation of craters generated by the electrical discharges. The dimensions of the crater generated by a single electrical discharge could offer an image concerning the material behavior during the electrical discharge machining and the phenomena corresponding to this machining technique. To ensure better conditions for the experiments development, a research schema based on the initiation of the single electrical discharge between the rectilinear edges of two parallelipiedic bars placed in plans perpendicular each other was applied. A factorial experiment with two independent variables at two levels was used to establish an empirical relation type power; the relation emphasizes the influence exerted by the voltage and by the capacity of the relaxation circuit on the dimensions of the crater. The sizes of the exponents proves the bigger influence exerted by the input factors on the crater width.

Slots and channels are sometimes necessary in machine building; the surfaces of the slots and channels could be obtained by means of a laser beam machining equipment. Essentially, the material removal from the workpiece needs the development of thermal phenomena of melting and vaporizing and of dynamic phenomena, respectively, by which the melted and vaporized material is moved from the machining zone. The paper includes the results of the researches concerning the possibilities to use 1070 nm wavelength laser equipment whose output power is of 300 W, in order to obtain slots and channels in metallic test pieces. The sizes of the parameters able to characterize the machined surface are influenced by the machining conditions. The theoretical analysis of the machining process highlighted the necessity of sending a compressed air jet along the laser beam axis and of an adequate selection of the machining parameters. Experimental researches were developed by changing the speed of the relative motion between the laser spot and the test piece. Empirical relations were established by mathematical processing of the experimental results. The empirical relations highlight the influence exerted by speed between the test piece and the laser beam on the depth of the channels thus generated.