DRILLING APPLICATIONS Designed to drill soft-medium and mediumhard formations up to 150 MPa/22,000 PSI with semi-abrasive characteristics. The HDL40 has a proprietary journal bearing. The HDL40 has a 537 cutting structure that is designed to drill all sedimentary rocks including sandstone, mudstone, claystone and shale, as well as low to medium strength igneous and metamorphic rocks.