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There are situations where parts manufactured by 3D printing processes must have a high abrasion resistance. To conduct experimental research on this subject, relatively simple test equipment for abrasive wear of pin-on-disk type was designed and materialized. The test pieces from the research material were pressed with known forces on the surface of a rotating abrasive paper disk. The test pieces were made of polyethylene terephthalate PET and polyethylene terephthalate carbon fiber reinforced PET CF15. As output parameters, the speed of decreasing the mass and the length of the test piece were used, respectively, for predetermined test durations. An experimental Taguchi L8 program was used, with 7 independent variables at two levels of variation. The experimental results were mathematically processed determined empirical mathematical models of the power function type. It was found that the strongest influence on the values of the output parameters was exerted by the average travel speed and by the granulation of the particles incorporated in the abrasive paper disk.

During the development of an electrical discharge machining (EDM) process, both the tool electrode and workpiece are affected by reducing their weight. In the case of roughing operations, it is important to have information concerning the material removed from the tool electrode. The problem seems to have interesting aspects when simultaneously machining of workpieces that include two or more different materials with the same electrode. In such a case, the tool electrode could be differently affected in the workpiece zones where there are various materials. To investigate the tool electrode wear when simultaneously EDM of a workpiece that included different materials, experimental research was designed and developed. Thus, a plate-type test sample made of steel and coated with a layer of titanium nitride on the two lateral surfaces was machined using a narrow blade-type tool electrode. Applying other machining conditions, different wears of the tool electrode zones affected by the EDM were observed. By mathematical processing of the experimental results, power type empirical mathematical models able to highlight the influence exerted by selected process input variables on the blade-type tool electrode wear were established. The empirical mathematical models could facilitate the selection of the process input values able to ensure a certain equalizing of the tool electrode wear in the zones where different materials are machined.

During the electrical discharge machining process, the electrical discharges are developing between the close asperities that exist on the tool electrode and workpiece surfaces, along a trajectory of minimum electrical resistance. As a consequence of the electrical discharges, small quantities of the electrode’s materials are melted or even vaporized and afterward removed from the machining gap. Various factors exert influence on the material removal from the peaks of asperities placed on the electrode’s surfaces. An experimental method of the simulation of the material removing process was designed and applied. Single electrical discharges characterized by distinct energies were generated between the conical peaks of the previously prepared test pieces made of some electroconductive materials and the flat surface of the copper electrodes. The quantities of the material removed from the conical peaks of the test piece materials under the action of electrical discharges were measured and used to determine empirical mathematical models. These models highlight the influence exerted by some factors specific to the electrical discharges (cone angle, the voltage between electrodes, the capacitance of the capacitors included in the discharge electric circuit) on the material removal from the conical peaks of the test pieces.

The obtaining of information concerning the processability by injection of plastics could facilitate a better design of injection manufacturing processes of parts made of such materials. With this aim in view, equipment for testing the processability by injection of plastics was designed. On the other hand, there are known the possibilities of using the axiomatic design principles to solve equipment or various design activities problems. Within this paper, an evaluation of the complying with the requests of the axiomatic design by the designed equipment was developed. The axiom of independence of the functional requirements necessary to be achieved by the equipment was applied. The analysis allowed the formulation of some remarks concerning the fulfillment of some principles of axiomatic design by the constructive solution proposed for the equipment for testing the processability by injection of plastics.

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.

One of the processes used to separate parts from plate-type workpiece is laser beam cutting. The evaluation of the quality of the machined surfaces can be performed by taking into account the influence exerted by some input factors in the cutting process on the width of the slot and on the roughness of the surfaces generated by the laser beam cutting process. The paper presents the results of experimental research performed on a steel plate type workpiece. The objective pursued was to reveal the influence exerted by several input factors of the laser beam cutting process on some output parameters of this process. Empirical mathematical models corresponding to the output parameters taken into account were established. It was possible to order the input factors in the process by taking into consideration their weight in the values of the output parameters.

Wire electrical discharge machining has appeared mainly in response to the need for detachment with sufficiently high accuracy of parts of plate-type workpieces. The improvements introduced later allowed the extension of this machining technology to obtain more complex ruled surfaces with increasingly high requirements regarding the quality of the machined surfaces and the productivity of the wire electrical discharge machining process. Therefore, it was normal for researchers to be interested in developing more and more in-depth investigations into the various aspects of wire electrical discharge machining. These studies focused first on improving the machining equipment, wire electrodes, and the devices used to position the clamping of a wire electrode and workpiece. A second objective pursued was determining the most suitable conditions for developing the machining process for certain proper situations. As output parameters, the machining productivity, the accuracy, and roughness of the machined surfaces, the wear of the wire electrode, and the changes generated in the surface layer obtained by machining were taken into account. There is a large number of scientific papers that have addressed issues related to wire electrical discharge machining. The authors aimed to reveal the aspects that characterize the process, phenomena, performances, and evolution trends specific to the wire electrical discharge machining processes, as they result from scientific works published mainly in the last two decades.

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.

Rotational molding is a manufacturing method which supposes the rotation of the mold, during the solidification of the liquid phase material, so that finally a part having a hollow could be obtained. The method could be applied in manufacturing of metallic and nonmetallic parts. Usually, the equipment for rotational molding ensures slow speed rotating of the mold around two axes placed perpendicularly each other and this fact led to relatively complex equipment for achieving rotational molding. The capacity of the liquid material to entirely cover the internal walls of the mold depends essentially on the liquid material viscosity, on the rotation speed and on the movements applied to the mold. Simplified equipment including a single rotation movement could be materialized. In order to test such a solution, a preliminary experiment was designed and materialized, by using a device adapted on universal lathe. Thus, the objective of the research presented in the paper was to study if it is possible to achieve plastic parts made by rotational molding using a single rotation movement. A polyurethane resin obtained from two liquid components was used in order to obtain the liquid material that could be introduced in the mold. The research results proved the possibility to use simplified equipment for achieving a rotational molding process, at least in certain cases and with some technological limits.

When for a certain design problem many alternative solutions could be susceptible to be used, a selection activity should be developed. If in the case of simple problems, the identification of an applicable alternative could be made very fast, in the case of the complex problems, the identification of the most convenient alternative could constitute itself a difficult problem. Over the years, simpler or more complex methods were found and applied to help the problem solver in finding the most convenient applicable alternative. The selection of a certain alternative when many such alternatives seem to exist could be made using the double input matrix method and the method of the pairwise comparison matrix and distinct evaluation criteria. The results of a applying the two selection methods in the case of necessity to establish a machining scheme for an electrical discharge machining process were presented in the paper.

Among other problems to be solved, the design of a technological process of machining by cutting a part involves establishing the dimensions that can be achieved in the pre-final machining of the same surface of the part. There are distinct ways to calculate the so-called intermediate dimensions and, in particular, to define the dimensions for adjusting the position of the cutting tool tip before starting the actual machining process. The paper analyzes some such ways of establishing the intermediate dimensions, highlighting the conditions under which they can be applied, their advantages and limitations of use. Subsequently, the double-entry matrix method was applied to identify one or more methods with wider possibilities of use. It was concluded that the method of tolerance chart and respectively a method that takes into account a statistical processing of the results accumulated over time are methods likely to lead to an efficient solving the problem of determining the intermediate dimensions.

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.

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.

Hybrid electrochemical discharge machining is a machining method materialized by distinct techniques which combines effects of material removal specific to electrochemical machining and electrical discharge machining. The research presented in this paper aimed to design, build and test an in-house equipment for hybrid electrochemical discharge machining and to study the electrochemical discharge drilling using a rotating tool and a passivating electrolyte. Theoretical conditions for obtaining small diameter holes by electrochemical discharge drilling were investigated. One considered that an aqueous solution of soluble sodium silicate would behave as a passivating electrolyte. In order to break and remove the passivating film, the rotating cylindrical tool could be periodically pressed on workpiece surface, the equipment being designed considering the above mentioned work motions. The equipment was built and the results of preliminary experimental tests proved the possibilities of obtaining small diameter holes, by using cylindrical tools of 0.5-1.0 mm diameter, with periodical increasing of the distance between the frontal surface of the tool electrode and the workpiece surface. The shape of current and voltage pulses were highlighted by use of data acquisition board.

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.

In order to obtain small diameter external surfaces by ram electrical discharge machining from plate workpieces, tubular tool electrodes could be used. In such a case, one can appreciate that the obtained surface is a simple concatenation of cavities appeared as a consequence of electrical discharges developed between the asperities existing initially on the active surface of the tool electrode and surface to be machined of the workpiece. The analysis of the surface generation as a consequence of the electrical discharge machining process showed that due to the surface tensions, a leveling phenomenon could be taken into consideration. An experimental study of influence exerted by some input factors on the surface roughness parameter Ra was designed and achieved. One noticed that the increase of the pulse on time, pulse off time and peak current intensity determines an increase of the surface roughness parameter Ra. By mathematical processing of the experimental results, an empirical model type power function was determined. The examination of the machined surface by means of an optical microscope showed the existence of microcavities generated by the electrical discharge, while the material melted and re-solidified was placed as a bordure of the microcavities.

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.

The elaboration of a modern manufacturing technology needs a certain quantum of information concerning the part to be obtained. When it is necessary to elaborate the technology for an existing object, such an information could be ensured by using the principles specific to the reverse engineering. Essentially, in the case of this method, the analysis of the surfaces and of other characteristics of the part must offer enough information for the elaboration of the part manufacturing technology. On the other hand, it is known that the laser marking is a processing method able to ensure the transfer of various inscriptions or drawings on a part. Sometimes, the laser marking could be based on the analysis of an existing object, whose image could be used to generate the same object or an improved object. There are many groups of factors able to affect the results of applying the laser marking process. A theoretical analysis was proposed to show that the heights of triangles obtained by means of a CNC marking equipment depend on the width of the line generated by the laser spot on the workpiece surface. An experimental research was thought and materialized to highlight the influence exerted by the line with and the angle of lines intersections on the accuracy of the marking process. By mathematical processing of the experimental results, empirical mathematical models were determined. The power type model and the graphical representation elaborated on the base of this model offered an image concerning the influences exerted by the considered input factors on the marking process accuracy.The elaboration of a modern manufacturing technology needs a certain quantum of information concerning the part to be obtained. When it is necessary to elaborate the technology for an existing object, such an information could be ensured by using the principles specific to the reverse engineering. Essentially, in the case of this method, the analysis of the surfaces and of other characteristics of the part must offer enough information for the elaboration of the part manufacturing technology. On the other hand, it is known that the laser marking is a processing method able to ensure the transfer of various inscriptions or drawings on a part. Sometimes, the laser marking could be based on the analysis of an existing object, whose image could be used to generate the same object or an improved object. There are many groups of factors able to affect the results of applying the laser marking process. A theoretical analysis was proposed to show that the heights of triangles obtained by means of a CNC marking eq...

The examination of the main machining methods applied in manufacturing processes from machine building and based on material removal from workpiece highlights essentially the existence of distinct processes able to generate material. An analysis of certain machining methods able to develop processes of material removal from workpieces was initiated by taking into consideration the principle machining schema and the capacity of generating machined surfaces. One concluded that within distinct machining processes, various phenomena are applied in order to obtain material removal from workpiece.

Nonconventional machining methods are based on the transfer of the energy to the work zone in ways distinct from those applied in the case of the so-called classical machining methods. A group of nonconventional machining methods achieve material removal from workpiece by using the motion of the electrical charged particles in a liquid. Practically, some machining techniques included in the larger groups of electrical discharge machining and in electrochemical machining are based on the motion of electrical charged particles in fluid. The problem addressed in this paper is to identify the zones where differences between the two groups of machining methods appear. A theoretical analysis was developed in order to identify the common aspects and respectively the differences between the electrical discharge machining and electrochemical machining, if the machining liquid is considered. Some experimental tests were developed to highlight aspects specific to the above mentioned machining techniques. The research facilitated obtaining a more complete image of some common and distinct characteristics of electrical discharge machining and electrochemical machining. The significance of the electroconductive or insulating properties of the work liquid was highlighted.

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.

Electrochemical discharge machining (ECDM) is based on synergetic action of anodic dissolution with erosive effect of electrical discharges in material removal process. Drilling by ECDM can be applied for hard to be cut materials, when no drilling by cutting or no EDM machine is available.

The performance of a high speed milling process of hardened tool steel depends on various machining conditions which affect the surface quality achieved on the component, the cutting force involved, the mechanism of chip formation, etc. The paper propose is to experimental investigate the cutting forces involved in the machining of a difficult-to-cut material, AISI W1 steel of different hardness states.

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.

Electrical discharge machining is a method that could be applied in order to detach cylindrical parts from a workpiece made of electroconductive material. If cylindrical tube is used as tool electrode, the machined surface could have a conical shape, due to the presence in the work gap of the electroconductive particles, detached from electrodes. Experimental researches were developed in order to obtain information concerning the shape error of machined surface. As a result of the experimental observation, improved technological solutions were identified and investigated. The experimental results proved certain possibilities of shape error decrease.

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.

As other nonconventional machining methods, the electrical discharge machining is applied when the workpieces materials are difficult to be machined by classical machining methods or the surfaces could not be obtained in efficient conditions by classical machining methods. Such a situation could appear, for example, when test pieces must be separated from materials whose machining by classical methods is difficult. Taking into consideration the necessity to detach a cylindrical test piece from a workpiece made of a high resistance metallic alloy, the problem of using the electrical discharge machining was formulated. An initial experimental test by using the common work motion of the tool electrode from up to down highlighted high shape errors, due to the accumulation in the work zone of the particles detached from the workpiece and from the tool electrode, as a consequence of electrical discharge machining process. A second set of experiments were developed, placing the test piece over the electrode tool and ensuring a work motion of workpiece from up to down; in this situation, a diminishing of the shape error was noticed. The second set of experiments highlighted a relatively reduced conicalness of the machined surface and a low decrease of the machining speed. as the penetration depth of the tool electrode in the workpiece increases, too.

The electrical dischargemachining (EDM) is known as the machining method in which the material removalis the result of developing electrical discharges having certain energetic andtemporal characteristics between the workpiece and the active surface of thetool electrode, while a dielectric liquid is circulated in the gap, essentiallyin order to remove debris. The last decades showed that in certain conditions,the dielectric liquid could be replaced by gaseous dielectric fluids, theprocess being named dry EDM. In the paper, some preliminary considerations areformulated about the material removal process for dry EDM drilling. Experimental researches were developed byconsidering the modifying of the values of some electrical characteristics(peak current, on time, off time and applied voltage) and determining thequantity of material removed from the test piece and the wear of the toolelectrode. The experimental results were mathematically processed and empiricalrelations were determined; these mathematical relations highlight the influenceexerted by the input parameters on the material removal rate.

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.

As consequence of the development of electrical discharge machining process, the electrode is affected by wear; knowing the evolution of the electrode wear, a better estimation of its service life is possible. It is expected that the electrode wear depends on the energy of the electrical discharges and the mass of the electrode. It is known also that the nature of the workpiece material exerts influence on the evolution of the electrode wearing process. In the paper, some theoretical considerations are used to highlight the above mentioned aspects. A set of experimental tests was designed and developed in order to highlight the influence exerted by the nature of the workpiece material and by the size of the cross section of the electrode, respectively, on the electrode wear. Empirical mathematical models corresponding to the evolution of the electrode wear were established.

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.

In the case of workpieces made of difficult-to-cut materials, the small-diameter holes (1 mm diameter below) can be obtained by means of various nonconventional machining methods, one of these being the hybrid electrochemical discharge machining (ECDM). In the literature they researched, the authors could not find enough information that would allow them to establish adequate work conditions for the ECDM of small diameter holes by using an electrolyte. The use of a spring in order to obtain the work motion required to drill thin workpieces, and the need to remove the insulating film appearing on the workpiece, including in the last stage of the machining, were considered. The experimental research ended in the development of a power type function, which emphasizes the influence of the electrode tool diameter, of the voltage applied to the electrodes, of the capacity of the electric circuit involved in obtaining the electrical discharges, and of the density of the electrolyte upon the absolute axial wear o...

The abrasive jet machining is a machining method based on the effects generated by the action of the abrasive particles sent to the workpiece surface to be machined by means of a high pressure gas jet. Essentially, the obtained surface could be considered as constituted by chaining microcraters resulted as a consequence of the abrasive particles action. Taking into consideration the possible influence exerted by some abrasive jet machining process input factors, an experimental research was developed. By mathematical processing of the experimental results, empirical mathematical models were determined to highlight the influence exerted by the average dimension of the abrasive particles, the distance between the nozzle and the flat surface of the test piece and the impact angle on the surface roughness parameter Rz. In order to evaluate the similarities between distinct zones of the machined surface profile, the value of the Pearson's coefficient was also determined.

Electrical discharges can be used to improve the operational properties of the surface layer of parts by using the phenomena of tempering, alloying, and deposition. Various techniques of alloying or deposition have been studied so far and sometimes even applied in the industry. The systemic approach of the deposition process shows which input and output factors can be taken into consideration. This article presents the experimental results obtained by using the deposition process based on the introduction of additional material such as powders put directly in the plasma channel corresponding to the electrical discharge. The established empirical mathematical models emphasize the influence exerted by the work gap value between the electrode and the workpiece, the powder flow, the delivered energy, and the specific energy on the quantity of added material.

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 dry electrical discharge machining is considered by the researchers as an environment friendly machining process and different specific aspects of this machining method are presented in the specialty literature. To obtain holes by electrical discharge machining, tubular rotating electrodes tools could be used. The paper presents a relatively simple device proposed to be used for applying the dry electrical discharge drilling. The rotation of the electrode tool could contribute to the diminishing of the errors of the circular shape in a cross section through the hole. Some preliminary experiments proved the possibilities to use this device to achieve holes in workpieces of low thickness. Test pieces made of stainless steel were machined by dry EDM and by common EDM. For the applied operating conditions, the dry electrical discharge drilling presents some advantages regarding the machined surface quality and the electrode tool wear, in comparison with the machining that uses liquid dielectric.

The diminishing of the surface roughness of a metallic part can be performed by using various finishing methods, polishing by means of abrasive flap wheels being one of them. There are several factors that influence the roughness of surfaces finished by means of abrasive flap wheels. When polishing external cylindrical surfaces by means of abrasive flap wheels, the surface roughness can be changed more easily if the following elements are modified: the peripheral speed of the workpiece and of the abrasive flap wheel, the speed of the longitudinal feed, and the grit size of the abrasive material. Experimental research has allowed for the establishment of power-type functions which highlight the influence exerted by the above-mentioned factors on the size of the surface roughness parameters R a , RS, RSm, Rku. Analyses of the experimental results have shown that, in the case of the R a roughness parameter, from among the range of interactions of orders 2 and 3, only the interaction between the rotation speed of the abrasive flap wheel and the speed of the longitudinal feed seems to be significant.

The electrochemical discharge machining (ECDM) offers an alternative to high technology equipments for drilling of small diameter holes in the case of difficult to machine materials. For a machining system based on the semidielectric liquid use and on the electric discharges initiated by contact break-out, the weight factor of the electrodes contact period is evaluated and the weight factor of the electrical discharges during this contact period is expressed. The paper presents some geometrical considerations which permit to conclude that the material removal rate depends on the characteristics of the motion and on some dimensions of the elements belonging to the crank mechanism. The influence of the input parameters on the axial electrode — tool wear and on the drilling speed is discussed.

In the machine manufacturing industries, cost estimation and costing are critical. In order to obtain maximum of technical and economical efficiency, in these cases, very important is to estimate the production costs and the production rates. Knowledge of investment and operating costs represents a base for investment in plasma arc cutting machine. For different plasma arc cutting machines typical investment costs and operating costs depend from the power of the plasma cutting machine and important system components. Knowledge of a plasma arc cutting system’s investment and operating costs should form the basis for evaluating its profitability. The high investment and operating costs, compared to conventional methods, must be justified according to economic criteria with corresponding financial advantages. In this paper, a mathematical model for determining the cost of plasma arc cutting machining is presented.