Rock Drilling with Tungsten Carbide Bits
Considerable test work has been done with the detachable type of carbide bit. In general, these bits improved drilling operations, but at a bit cost .greater than was compensated for by the reduction in man-hours of labour. Too few bits continued :in service for the possible drilling life of the carbide inserts, and technical improvements or lowered first cost, preferaib1y both, are indicated in order that the ;bits can be generally acceptable as an economical drilling tool. In preliminary test work, the drill rods .with one insert of the chisel-bit type appear to be more trouble-free, to have a longer life, and to give a somewhat lower bit cost per foot drilled, than other types.
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