The selection of Cutter Rings depends on diferent ground conditions. There are four types of Cutter Ring: Wide Range and Hardfacing Cutter Ring is suitable for cohesive stratum with strength <40 MPa or the fractured conglomerate, sandstone and sand clay strata with strength ranging 80-100Mpa. TCI Cutting Ring is suitable for highly and moderately weathered sandstone, granite, basalt, porphyry and quartzite strata with the strength < 50MPa. Standard Cutter Ring is suitable for conglomerate, marble,sandstone and limestone strata with the strength of 50-150MPa. Heavy-duty Cutter Ring is suitable for 120-250MPa hard rock stratum, such as granite, diorite, porphyry, serpentine and basalt strata....