Nonconventional machining

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 of the electrode tool.

In this you can find how metalizing process occurs at high pressure and high vacuum. The metalizing process is used to glaze  the parts used in lighting systems for reflection of light and to improve the lux value. The process is too simple to understand if you know the basics of pressure and vacuum terminologies. The equipment used is fully automated and the cost of process i.e. cost per piece is very low. The thickness of aluminium layer adhered on the parts is very very thin i.e. some microns. This is an unique process and may help many of readers to know and study.

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.

Abrasive waterjet machining (AWJM) is a new machining process, the advantages of which include low cutting temperatures, no heat damage to the material being cut, minimal dust, and low cutting forces. This paper presents a state of the art review of research in this new process. The main topics discussed are mechanics of material removal, productivity, cutting forces, surface quality and nozzle wear.

This paper presents the development of mathematical model for cost optimization of abrasive water jet cutting. Mathematical optimization model includes the manufacturing cost as the objective function, the traverse rate for separation cut as the cutting performance function, and constraints. Outputs of the mathematical model for optimization are the values of orifice diameter, focusing tube diameter, traverse rate, water pressure and abrasive mass flow rate when the manufacturing cost is minimal. Genetic algorithms are used to find optimal process parameters.

Surface roughness in abrasive water jet cutting of carbon steel using Shainin method was investigated. Design of experiment with five factors (material thickness, water pressure, abrasive flow rate, traverse rate and standoff distance) each in two levels is employed to investigate surface roughness. Using Shainin method number of factors is reduced from five to three important and then is employed full factorial design to determine the effect of important factors on surface roughness. Regression analysis was used to find correlation between surface roughness and factors.

A B S T R A C T Multi-objective optimization of process performances (perpendicularity deviation, surface roughness and productivity) when cutting carbon steel EN S235 with abrasive water jet is presented in this paper. Cutting factors (abrasive flow rate, traverse rate and standoff distance) were determined when perpendicularity deviation and surface roughness are minimal and productivity is maximal. Multi-objective genetic algorithm (MOGA) was used for the determination set of nondominated optimal points, known as Pareto front.

Taguchi method is employed to investigate surface roughness of carbon steel machined by abrasive water jet. Design of experiment was conducted using L 8 orthogonal array with four factors (water pressure, abrasive flow rate, traverse rate and standoff distance) and two levels. Analysis of means, analysis of variance and signal-to-noise ratios are employed to determine influence of factors on surface roughness and to determine optimal factor levels. Regression analysis was used to find correlation between surface roughness and factors.

Abstract: The paper deals with study through Finite Element Method (FEM) of synchronization between pulses and tool oscillations at ultrasonics (US) aided micro-Electrodischarge Machining (μEDM) aiming at increasing the machining rate and the surface quality. These main output technological parameters at μEDM are not as good as they are expected due to instability of material removal process and long duration of gas bubble formed around plasma channel. The ultrasonic longitudinal oscillations of ...

Electrochemical discharge machining (ECDM) is considered to be a hybrid machining method where material removal is based on two phenomena: electrochemical dissolution of the material and thermal erosion by electrical discharges that occur between the electrodes. Obtaining holes of small diameter in hard materials is one challenge also for this machining method. The paper contains some results obtained by trying to achieve small diameters holes by electrochemical discharge machining using an aqueous solution of sodium silicate as working liquid. Identifying an optimized system for mechanical and electrical equipment was one of the targets of this research. By assuring a relative motion between the electrodes, holes (diameter

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.

Due to the chemical elements included in their structure for ensuring an increased resistance to the environment action, the stainless steels are characterized by a low machinability when classical machining methods are applied. For this reason, sometimes non-traditional machining methods are applied, one of these being the electrochemical discharge machining. To obtain microholes and to evaluate the machinability by electrochemical discharge microdrilling, test pieces of stainless steel were used for experimental research. The electrolyte was an aqueous solution of sodium silicate with different densities. A complete factorial plan was designed to highlight the influence of some input variables on the sizes of the considered machinability indexes (electrode tool wear, material removal rate, depth of the machined hole). By mathematically processing of experimental data, empirical functions were established both for stainless steel and carbon steel. Graphical representations were used to obtain more suggestive vision concerning the influence exerted by the considered input variables on the size of the machinability indexes.

Multi-objective optimization of process performances (perpendicularity deviation, surface roughness and productivity) when cutting carbon steel EN S235 with abrasive water jet is presented in this paper. Cutting factors (abrasive flow rate, traverse rate and standoff distance) were determined when perpendicularity deviation and surface roughness are minimal and productivity is maximal. Multi-objective genetic algorithm (MOGA) was used for the determination set of nondominated optimal points, known as Pareto front.

If the positive ions are placed in an intense electric field, they will be attracted and accelerated to the negatively charged piece. This phenomenon is currently used as part of an ion deposition process. One can consider that the deposition process is the result of the accelerated ions’ impact with the workpiece surface layer. In the specialty literature, the ion deposition process is included in the so-called larger category of the physical vapour deposition. This paper presents some considerations of the authors concerning the base phenomena and applied aspects of the ion deposition process. To improve some service properties (corrosion and wear resistance, friction coefficient etc.) of certain pieces or tools, thin layers of titanium nitride can be deposited on their surfaces. The titanium nitride deposition process can be regarded as a system; as input parameters, one may consider the type of the material to be deposited and of the substrate, the type of the gas existing or obtained in the vessel, the electrical parameters used to generate the ions and to accelerate them to the cathode, the pressure in the recipient etc. The paper includes some hypotheses developed by the authors regarding the phenomena occurring during the plasma deposition process of titanium nitride. There are also some considerations concerning the changing of the surface roughness as consequence of the plasma deposition process.