402. Which of the following statement is wrong about ultra-sonic machining?

[A]. It is best suited for machining hard and brittle materials.
[B]. It cuts materials at very slow speeds.
[C]. It removes large amount of material.
[D]. It produces good surface finish.
✅ The correct answer is option C.

406. The facing is an operation of

[A]. bevelling the extreme end of a workpiece
[B]. embossing a diamond shaped pattern on the surface of a workpiece
[C]. reducing the diameter of a workpiece over a very narrow surface
[D]. machining the ends of a workpiece to produce a flat surface square with the axis
✅ The correct answer is option D.