Which of following is true about ECG?

Applications of ECG are as follows;
(1) Single largest use for ECG is in the manufacturing and remanufacturing of turbine blades and vanes for aircraft turbine engines
(2) Grinding of tungsten carbide tool inserts
(3) Re-profiling worn locomotive traction motor gears
(4) Burr-free sharpening of hypodermic needles
(5) Grinding of surgical needles, other thin wall tubes, and fragile parts
(6) Machining of fragile or very hard and tough material ? honey comb, thin walled tubes and skins
(7) High MRR?s when grinding hard, tough, stringy, work-hardenable or heat sensitive materials.