Vicky(vicky0112@hotmail.com) PDC bit, also called PDC drilling bits, PDC diamond BIT Polycrystalline Diamond Compact or called PDC - These bits are expensive and used for very fast penetration mostly in shales. This bit has carbide or man-made industrial diamonds set in fixed blades. The cutters simply scrape the rock away during drilling, and do not rotate and grind the way the cones of a tri-cone bit do.