Deep hole boring machines, abbreviated as DHBMs, are a type of deep hole drilling and boring machine. They are categorized into horizontal DHBMs, vertical DHBMs, and 3-axis boring machines. Depending on the length of the workpiece, two machining processes are selected for DHBMs: short workpieces are lubricated by an oil feeder and hydraulically clamped; long workpieces are lubricated at the end of the boring bar and clamped by a four-jaw chuck.