ISE
MMM LECTURE NOTES FINAL.pdf

# Depending on the grain size of these particles a

• 83

This preview shows pages 38–43. Sign up to view the full content.

Depending on the grain size of these particles, a constant interelectrode gap (0.025 mm or less) through which the electrolyte is flushed can be maintained. Fig., Surface ECG.

This preview has intentionally blurred sections. Sign up to view the full version.

Modern Manufacturing Methods The abrasives continuously remove the machining products from the working area. In the machining system shown in Fig. 6.3, the wheel is a rotating cathodic tool with abrasive particles (60 320 grit number) on its periphery. Electrolyte flow, usually NaNO3, is provided for ECD.The wheel rotates at a surface speed of 20 to 35 m/s, while current ratings are from 50 to 300 A. Removal rates by ECG are 4 times faster than by conventional grinding,and ECG always produces burr-free parts that are unstressed. The volumetric removal rate (VRR) is typically 1600 mm3/min. McGeough (1988) and Brown (1998) claimed that to obtain the maximum removal rate, the grinding area should be as large as possible to draw greater machining current, which affects the ECD phase. The volumetric removal rate (mm3/min) in ECG can be calculated using the following equation: Where e = equivalent weight, g I = machining current, A r = density of workpiece material, g/mm3 F = Faraday’s constant, C
Modern Manufacturing Methods The speed of penetration of the grinding wheel into the workpiece, Vg (mm3/min), is given by Kalpakjian (1997) as follows: Where v = gap voltage, V gw = wheel-workpiece gap, mm Kp = coefficient of loss (1.5 3) k = electrolyte conductivity, Ω– 1mm 1 ECG is a hybrid machining process that combines MA and ECD. The machining rate, therefore, increases many times; surface layer properties are improved, while tool wear and energy consumption are reduced. While Faraday’s laws govern the ECD phase, the action of the abrasive grains depends on conditions existing in the gap, such as the electric field, transport of electrolyte, and hydrodynamic effects on boundary layers near the anode. The contribution of either of these two machining phases in the material removal process and in surface layer formation depends on the process parameters.

This preview has intentionally blurred sections. Sign up to view the full version.

Modern Manufacturing Methods The work of the abrasive grains performs the mechanical depolarization by abrading the possible insoluble films from the anodic workpiece surface. Such films are especially formed in case of alloys of many metals and cemented carbides. A specific purpose of the abrasive grains is, therefore, to depassivate mechanically the workpiece surface. Fig., ECD and MA in the machining gap during ECG.
Modern Manufacturing Methods Applications The ECG process is particularly effective for 1. Machining parts made from difficult-to-cut materials, such as sintered carbides, creep-resisting (Inconel, Nimonic) alloys, titanium alloys, and metallic composites. 2. Applications similar to milling, grinding, cutting off, sawing, and tool and cutter sharpening.

This preview has intentionally blurred sections. Sign up to view the full version.

This is the end of the preview. Sign up to access the rest of the document.
• Fall '12
• JeraldBrevick
• EDM, conventional machining processes, Jet Machining

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern