WEDMed Surface Research Articles

WEDM performance and surface integrity of Inconel alloy IN718 with coated and uncoated wires

In this work, using zinc-coated copper wire and uncoated brass wire, WED machining performance of IN718 was evaluated with input process variables, the discharge duration, pulse interval time, and wire runoff speed. The output variables analyzed are wire feed rate, kerf width, and recast layer characteristics. The experimental results show that zinc-coated copper wire is better in general performance when compared with uncoated brass wire. With the optimization of WEDM process parameters for the zinc-coated copper wire, it obtained 35% increase in wire feed rate and a reduction of 40% in wire consumption. When WEDM at optimized conditions with uncoated brass wire, it was found that 36% gain on wire feed rate with 80% reduction of wire consumption. Electrode material (Cu and Zn) from both wires was incorporated in the IN718 recast layer and in direction to matrix material. The kerf width is dependent on the discharge energy and wire runoff speed.

Effect of WEDM surface texturing on Al2O3/TiCN composite ceramic tools in dry cutting of hardened steel

Micro scale textures were fabricated on the rake surface of Al2O3/TiCN composite ceramic cutting tools using WEDM process. The cutting performance of ceramic cutting tools with plain and textured rake surfaces was investigated in the dry cutting of hardened AISI 52100 steel (62 HRC). The performance of cutting tools was evaluated by chip-tool contact length, tool wear, machining forces, cutting temperature, frictional coefficient and chip morphology. Further, a 3D finite element model has been used to study the temperature and stress distribution in the cutting tools. Application of textures obstructing the chip flow direction resulted in uniform stress distribution, and higher groove sliding area ensured maximum reduction of machining forces, material adhesion, cutting and tool temperature. However, the textures parallel to the chip flow direction resulted in bending and curling of chips on the rake face causing an increase of chip-tool contact length and material adhesion as compared to the tools with textures obstructing the chip flow resulting in an increase of friction. The textured tool with textures inclined at an angle to the chip flow direction exhibited the best machining performance as compared to other textured cutting tools. Moreover, this tool exhibited superior anti-adhesion behavior as compared to the conventional cutting tool owing to the reduced chip-tool contact length and area, friction and chip flow angle.

Surface Integrity Characteristics in Wire Electrical Discharge Machining of Titanium Alloy during Main cut and Trim cuts

Ti-6Al-4V grade titanium alloy is the most popular alloy and is used for a wide range of applications in aerospace, marine, power generation and offshore industries etc., because of its very good mechanical properties such as hightensile strength, fatigue resistance, highest strength-to-weight ratio, extraordinary corrosion resistance and toughness even at elevated temperatures. Wire Electrical Discharge Machining (WEDM) is extensively used for machining of complex shapes in the field of die and mould making, medical, aerospace and automobile industries for machining of too hard materials. WEDM is essentially a thermal process with a complex metal removal mechanism, involving the formation of a plasma channel between the wire/tool and workpiece, resulting in the material removal, which also leads to surface roughness, work hardness, over cut, white layer, heat effected zone, surface structural changes, metallurgical transformations and cracking. These properties determine the operational behaviour of the material and can be included in one term called surface integrity. In this Investigation multi cutting pass i.e. rough/main cut and trim/finish cut approach was adopted to improve the quality of surface characteristics of WEDM surface of Titanium alloy. The results show that the WEDMed surface topography shows dominant micro voids, thick white layer and heat affected zone and even micro cracks at high pulse on time and pulse current and these are low at low pulse on time and pulse current during trim cuts. Further surface topography and micro structural changes were observed through scanning electron microscopy (SEM) micrographs

Effects of wire-Cut EDM process parameters on surface roughness of HSLA steel

Wire-cut EDM is used to produce complex-shaped and delicate parts; however, surface roughness (SR) is entirely dependent on optimal combination of input process parameters which is a difficult task. In this research, surface roughness model has been developed for high-strength low-alloy (HSLA) steel (30CrMnSiA, 38HRC). A series of experiments using factorial designs of experiments have been conducted to develop relationship between SR and WEDM process parameters namely, pulse-on time, pulse ratio, power (discharge current), wire speed and pulse (discharge gap). It has been found that pulse-on time has the highest impact on SR followed by wire speed, power and pulse. WEDMed surface was also examined by scanning electron microscope (SEM) to study the physical behavior of these process parameters. Results of ANOVA also indicated that interaction effects are important for surface roughness in addition to main effects. Accuracy of the proposed model has been confirmed through residual analysis and validation experiments.

Lubricant Retention Property of Micro Wire Electrical Discharge Machining Surface

Based on the topography of micro WEDM surface, lubricant retention, bearing capability, and sealing performance were evaluated by using the surface bearing index, lubricant retention index of core area, and lubricant retention index of valley bottom respectively. The results show that the micro WEDM surface with the characteristic of isotropy texture is beneficial to store lubricating oil, and the lubricant retention property is superior to that of the traditional machining surface.

Modeling Study of Engineering Ceramics WEDM Based on Fuzzy Logic

relevance between technological parameter and processing effects in WEDM is extremely complex. In order to solve the difficulty of set up mathematical model for technological parameter and processing effects in engineering ceramics WEDM, an prediction model based on fuzzy logic is proposed through establish fuzzy controller by input/output fuzzification, fuzzy inference and settle fuzzy, whereas, build prediction model of engineering ceramics WEDM surface roughness change according to technological parameter utilizing established fuzzy logic controller in matlab. Laboratory finding shows, utilization of this model can precisely predict surface roughness under preset condition with relatively minus error, which further validate the reliability of this model. Keywords: Engineering ceramics, fuzzy logic, WEDM, processing optimization

Evaluation of WEDM Surface Quality

The formation of WEDM surface is a complicated process. There are many factors which make machined surface topography have the characteristics of complex and irregular, and impact using performance of parts. The work investigated microscopic features of the WEDM surface topography based on power spectral density and fractal theory, and proposed power spectral density evaluation method of the WEDM surface. The fractal dimension of the WEDM surface was calculated by structure function method. The physical meaning of the fractal dimension of the WEDM surface was described. The result shows that topography of the WEDM surface exhibits strong fractal characteristics within a certain scale. The processing parameters and pulse power performance will affect the fractal dimension D. The fractal dimension D has a certain relationship with the surface roughness Ra. It is more reasonable to use the fractal dimension D as well as the surface roughness Ra together to evaluate WEDM surface quality.

Dry WEDM in Improving LS-WEDMed Surface Quality

Utilizing gas as the dielectric instead of dielectric liquid has enabled the development of dry wire electrical discharge machining (dry WEDM) technology for finishing cut. Experiment results showed that Low-Speed WEDM (LS-WEDM) in gas offers advantages such as better straightness, and shorter discharge gap. This paper studies on influence of different gas dielectrics, wire winding speed and pulse duration on the WEDMed surface quality (discharge gap, straightness, surface roughness, removal rate) in finishing. New attempt of applying dry WEDM as the 4th cut had been proved feasible in improving conventional multiple cut surface quality of LS-WEDM.

Study on Dry WEDMed Surface Quality of Mould Steel

This paper studies the surface quality of tool steel with high-speed wire electrical discharge machining (WEDM) method, which is conducted in gas to improve the accuracy of finish cut, and compares the surface quality in atmosphere and in emulsion dielectric. Experiment results showed that WEDM in atmosphere offers advantages such as better straightness and higher material removal rate. With the growth of wire winding speed, the removal rate and straightness error will increase significantly either in atmosphere or in liquid. Along with the feed increasing, the discharge gap lengthes decrease successively under the both media conditions, and the straightness is obviously improved in atmosphere. Regardless of the use of atmosphere or emulsion, an optimum feed will exist, which makes the roughness the lowest and the removal rate the highest.

Study on Dry WEDMed Surface Layer of Cold Tool Steel SKD11

Study on Dry WEDMed Surface Layer of Cold Tool Steel SKD11

Parametric optimization and surface characterization of wire electrical discharge machining process

Wire electrical discharge machining (WEDM) technology has been widely used in conductive material machining. The WEDM process, which is a combination of electrodynamic, electromagnetic, thermaldynamic, and hydrodynamic actions, exhibits a complex and stochastic nature. Its performance, in terms of surface finish and machining productivity, is affected by many factors. This paper presents an attempt at optimization of the process parametric combinations by modeling the process using artificial neural networks (ANN) and characterizes the WEDMed surface through time series techniques. A feed-forward back-propagation neural network based on a central composite rotatable experimental design is developed to model the machining process. Optimal parametric combinations are selected for the process. The periodic component of the surface texture is identified, and an autoregressive AR(3) model is used to describe its stochastic component.