WANLONG
1. For soft to medium hard (referring to grades 1-6 in the diamond core drill bit drillability grading table) and intact homogeneous rock formations, natural surface-set drill bits, composite drill bits, polycrystalline drill bits and partially sintered drill bits can be selected.
2. For hard and dense rock formations (grades 7-12 in the grading table), impregnated drill bits, concentric ring groove drill bits or staggered ring groove drill bits, or fine-grained surface-set diamond core drill bits are generally selected.
3. For broken, soft and hard interlayered, crack-developed or highly abrasive rock formations, such as coal-bearing formations, sharp-toothed broad-spectrum drill bits or electroplated impregnated drill bits with better wear resistance should be selected.
4. The principle of selecting the wear resistance of the matrix according to the abrasiveness, weathering degree and crushing degree of the rock is:
(1) For highly abrasive rock formations, a highly wear-resistant matrix should be selected.
(2) For moderately abrasive rock formations, a moderately wear-resistant matrix should be selected. For weakly abrasive rock formations, a low-wear-resistant matrix should be selected.
(3) For complex rock formations, the stronger the rock abrasiveness and the higher the hardness, the better the matrix grade and the finer the particle size.
(4) Strong abrasiveness. While ensuring good diamond embedding, a diamond drill bit with a higher diamond concentration should be selected. Conversely, for homogeneous and dense rock formations with weak abrasiveness, a diamond core drill bit with a lower diamond concentration should be selected.
(5) For soft rock formations with large dust discharge (grades 1-4), a composite drill bit or polycrystalline drill bit should be selected. For coring easily corroded rock and mineral formations, a bottom jet drill bit should be used.
