Study on the improvement of the surface integrity and efficiency of electrical-discharge-machined TC4 titanium alloy via abrasive flow machining

Author(s):  
Ze Yu ◽  
Dunwen Zuo ◽  
Yuli Sun ◽  
Guohua Li ◽  
Xuemei Chen ◽  
...  

To simultaneously optimize the surface quality and machining efficiency of the electrical discharge machining (EDM) processes used to produce titanium alloy quadrilateral group small hole parts, a combined “EDM + AFM” machining technology is proposed in this paper as an efficient and high-quality machining approach. In the proposed method, TC4 titanium alloy is first machined using the EDM process with graphite electrodes and the abrasive flow machining (AFM) process is then used to finish the machined surface. The effects of various electrical parameters on EDM-derived surface quality and improvements in EDM-derived quality under the application of AFM were assessed and, using the final surface roughness as a constraint condition, the effects of various combinations of EDM and “EDM + AFM” on efficiency were studied. The results revealed that the thickness and surface roughness of the superficial recast layer of the TC4 titanium alloy increase with both current and pulse width; in particular, increasing these parameters can increase the surface roughness by two to three grades. Following AFM, the alloy has a more uniform hardness distribution and the surface stress state changes from tensile to compressive stress, indicating that the combined “EDM + AFM” machining scheme can significantly enhance the surface quality of EDM-produced titanium alloy quadrilateral small group holes. The combined scheme achieves a balancing point beyond which increasing the roughness or the number of machining holes enhances either the machining efficiency or the machining surface quality. In the case of typical titanium alloy quadrilateral group small hole parts, the combined machining process can improve the finishing efficiency and total machining efficiency by 71.2% and 25.36%, respectively.

Materials ◽  
2021 ◽  
Vol 14 (20) ◽  
pp. 5943
Author(s):  
Arminder Singh Walia ◽  
Vineet Srivastava ◽  
Mayank Garg ◽  
Nalin Somani ◽  
Nitin Kumar Gupta ◽  
...  

In electrical discharge machining (EDM), the machined surface quality can be affected by the excessive temperature generation during the machining process. To achieve a longer life of the finished part, the machined surface quality plays a key role in maintaining its overall integrity. Surface roughness is an important quality evaluation of a material’s surface that has considerable influence on mechanical performance of the material. Herein, a sintered cermet tooltip with 75% copper and 25% titanium carbide was used as tool electrode for processing H13 steel. The experiments have been performed to investigate the effects of EDM parameters on the machined surface roughness. The findings show that, as the pulse current, pulse length, and pulse interval are increased, the surface roughness tends to rise. The most significant determinant for surface roughness was found to be pulse current. A semi-empirical surface roughness model was created using the characteristics of the EDM technique. Buckingham’s theorem was used to develop a semi-empirical surface roughness prediction model. The semi-empirical model’s predictions were in good agreement with the experimental studies, and the built empirical model based on physical features of the cermet tooltip was tested using dimensional analysis.


Author(s):  
Kursad Gov ◽  
Omer Eyercioglu

In this article, the effect of abrasive types on the abrasive flow machining process was investigated. Four groups of abrasive media were prepared with different types of abrasives: SiC, AL2O3, B4C and Garnet. An experimental study was performed on DIN 1.2379 tool steel. The specimens were cut using wire electrical discharge machining and finished with the abrasive flow machining process. The results show that the white layer that formed during wire electrical discharge machining was successfully removed by abrasive flow machining in a few cycles. Although the surface roughness improves with similar trends for all media groups, the results show that the media prepared with B4C and SiC have more surface improvement than the Al2O3 and Garnet ones. The resulting average surface roughness (Ra) values are comparable to the surface quality of those obtained from lapping and super-finishing. The material removal is directly related to the hardness of the abrasive.


2016 ◽  
Vol 724 ◽  
pp. 61-65 ◽  
Author(s):  
Ahmad Majdi Abdul-Rani ◽  
Alexis Mouangue Nanimina ◽  
Turnad Lenggo Ginta

This research study was conducted to investigate the effect of nanoaluminum powder mixed electrical discharge machining (PMEDM) on surface morphology and corrosion rate of titanium alloy material. The development of devices such as implants in biomedical engineering application nowadays requires materials having good mechanical and physical properties. Conventional machining process of titanium as implant is a challenge resulting relative poor surface quality. Even using electrical discharge machining (EDM) which is non-conventional machining process there are limitations including machined surface alteration with relative poor machined surface quality, low corrosion resistance and. PMEDM is hypothesized to address the above mentioned problems. In this study, PMEDM on titanium alloy using nanoaluminum powder and copper-tungsten electrode was assessed to investigate the improvement for implant application. Process parameters used are peak-current, ON-time, gap voltage and powder concentration. Surface morphology and average corrosion arte are selected output responses. Results showed that Surface morphology of PMEDM machined surface is significantly improved. PMEDM marginally enhanced corrosion rate of biomedical grade titanium alloy.


2007 ◽  
Vol 359-360 ◽  
pp. 374-378
Author(s):  
Ming Rang Cao ◽  
Shi Chun Yang ◽  
Wen Hui Li ◽  
Sheng Qiang Yang

The EDM can machined some superhard conducting material that cannot be handled by the traditional method, such as carbide alloy, tool steel and engineering materials etc., however, it is also accompanied with slow material removal rate(MRR) and poor surface quality (surface roughness). For some fine machining having rigorous criterion on size and surface roughness, the EDM cannot meet the demand. Some researches indicate that the MRR of small hole by electrical discharge machining combined with ultrasonic vibration (UEDM) can increase in certain range, but the surface quality is still poor. Although there are lots of the researches on the UEDM, some debates on machining mechanism and applied scope existed, and technology of UEDM needs the further study. After small hole machined by the UEDM, it is polished by ultrasonic vibrating. Two steps are includes in this technology. In the first place, on a high velocity electro discharge small hole machine with high-pressure dielectric liquid and hollow electrode, a transducer and horn are attached between the spindle and the electrode. The ultrasonic vibration of the tool electrode is implemented by connecting the horn and the tool electrode together with a chucking appliance. The second, after the small hole is complete, with the same machine tool and tool electrode the process of polishing the inwall of the small hole is carried out by accompanying the ultrasonic vibration, revolution and feed of the tool electrode with the abrasive material. In the experiments, the reference point for UEDM is found and the new theory is proposed to explain the increase of the MRR and the decrease of the surface roughness value .The polish with the ultrasonic vibration can improve further the surface roughness. The ultrasonic vibrating polish after the hole by UEDM is an economical and effective technology, which realizes machining of two procedures in one machine tool. So the process for changing machine tool and tool is not needed any more and the efficiency is further improved.


2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Nirdesh Ojha ◽  
Florian Zeller ◽  
Claas Mueller ◽  
Holger Reinecke

Electrical discharge machining (EDM) is widely used to manufacture complex shaped dies, molds and critical parts in conductive materials. With the help of an assisting electrode (AE), EDM process can be used to machine nonconductive ceramics. This paper evaluates the mechanical properties of three high-performance nonconductive ceramics (ZrO2, Si3N4, and SiC) that have been machined with the EDM process using AE. Mechanical properties such as Vickers hardness (HV 0.3), surface roughness (Sq), and flexural strength of the machined and the nonmachined samples are compared. The EDM process causes decrease in Vickers hardness, increase in surface roughness, and decrease in flexural strength.


Author(s):  
Murahari Kolli ◽  
Adepu Kumar

Surfactant and graphite powder–assisted electrical discharge machining was proposed and experiments were performed on titanium alloy in this investigation. Analysis was carried out to observe changes in dielectric fluid behaviour, material removal rate, surface roughness, recast layer thickness, surface topography and energy-dispersive X-ray spectroscopy. It was found out that the addition of surfactant to dielectric fluid (electrical discharge machining oil + graphite powder) improved the material removal rate and surface roughness. It was noticed to have reduced the recast layer thickness and agglomeration of graphite and sediment particles. Biface material migrations between the electrode and the workpiece surface were identified, and migration behaviour was powerfully inhibited by the mixing of surfactant. Surfactant added into dielectric fluid played an important role in the discharge gap, which increased the conductivity, and suspended debris particles in dielectric fluid reduced the abnormal discharge conditions of the machine and improved the overall machining efficiency.


Mechanik ◽  
2018 ◽  
Vol 91 (10) ◽  
pp. 915-917
Author(s):  
Jan Burek ◽  
Robert Babiarz ◽  
Marcin Płodzień ◽  
Jarosław Buk

The article presents the effect of electrode infeed in finishing machining of disk fir tree slots made of Inconel 718 alloy on shape accuracy and surface roughness in WEDM (wire electrical discharge machining).


2018 ◽  
Vol 14 (4) ◽  
pp. 115-124 ◽  
Author(s):  
Shukry H. Aghdeab ◽  
Nareen Hafidh Obaeed ◽  
Marwa Qasim Ibraheem

Electrical Discharge Machining (EDM) is a non-traditional cutting technique for metals removing which is relied upon the basic fact that negligible tool force is produced during the machining process. Also, electrical discharge machining is used in manufacturing very hard materials that are electrically conductive. Regarding the electrical discharge machining procedure, the most significant factor of the cutting parameter is the surface roughness (Ra). Conventional try and error method is time consuming as well as high cost. The purpose of the present research is to develop a mathematical model using response graph modeling (RGM). The impact of various parameters such as (current, pulsation on time and pulsation off time) are studied on the surface roughness in the present research. 27 samples were run by using CNC-EDM machine which used for cutting steel 304 with dielectric solution of gas oil by supplied DC current values (10, 20, and 30A). Voltage of (140V) uses to cut 1.7mm thickness of the steel and use the copper electrode. The result from this work is useful to be implemented in industry to reduce the time and cost of Ra prediction. It is observed from response table and response graph that the applied current and pulse on time have the most influence parameters of surface roughness while pulse off time has less influence parameter on it. The supreme and least surface roughness, which is achieved from all the 27 experiments is (4.02 and 2.12µm), respectively. The qualitative assessment reveals that the surface roughness increases as the applied current and pulse on time increases


2014 ◽  
Vol 68 (1) ◽  
Author(s):  
Md. Ashikur Rahman Khan ◽  
M. M. Rahman

Electrical discharge machining (EDM) produces complex shapes and permits high-precision machining of any hard or difficult-to-cut materials. The performance characteristics such as surface roughness and microstructure of the machined face are influenced by numerous parameters. The selection of parameters becomes complicated. Thus, the surface roughness (Ra) and microstructure of the machined surface in EDM on Grade 6 titanium alloy are studied is this study. The experimental work is performed using copper as electrode material. The polarity of the electrode is maintained as negative. The process parameters taken into account in this study are peak current (Ip), pulse-on time (Ton), pulse-off time (Toff), and servo-voltage (Sv). A smooth surface finish is found at low pulse current, small on-time and high off-time. The servo-voltage affects the roughness diversely however, a finish surface is found at 80 V Sv. Craters, cracks and globules of debris are appeared in the microstructure of the machined part. The size and degree of craters as well as cracks increase with increasing in energy level. Low discharge energy yields an even surface. This approach helps in selecting proper process parameters resulting in economic EDM machining. 


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