Advanced Machining : Practice Questions and Answers

The grinding wheel is cathode and the work piece is anode in the Electro chemical grinding process.

Electro chemical grinding process removes the material mainly by electro chemical dissolution.

The current density values in Electro chemical grinding depend on machined material, gap width and the applied voltage.

The values of current densities range from 120 to 240 A/cm2.

The value of the gap voltage in ECG process is 4 to 40 V.

Both pulsed CO2 and Nd-YAG lasers can be used for ceramic materials in LBM.

Pulsed CO2 laser is used for organics and non-metallic materials in Laser beam machining process.

CO2 laser is used for slitting of thin plastic materials in Laser beam machining process.

Nd-YAG laser is used for slitting of thin metallic materials in Laser beam machining process.

CO2 + gas assisted laser is used for cutting thicker materials in Laser beam machining process.

Both Ruby and Nd-YAG laser can be used for direct (percussion) drilling purpose.

Nd-YAG laser can be used for drilling small holes as well as large holes by trepanning process.

Brittle materials such as silicon, glass and ceramics may be effectively shaped or separated by laser scribing.

In LBM, material removal at the rate of milligrams per pulse produces shallow holes in the material.

Lasers of high power density, small spot size and short pulse length are useful devices for modification of electronic components.

The practical advantages of excimer laser are mainly due to short laser wavelength and pulse duration.

The thickness of material used in fine cutting process vary from 0.5 to 16 mm.

Work piece tilting depends on the incident power, beam speed, groove direction, and optical absorption coefficient of the material.

Grooves on the grinding wheels are produced due to evaporation and damage of the composite wheel material.

Dressing of grinding wheels, scribing, micromachining, controlled fracturing are some of the other applications of Laser beam machining.