Machine Tools

Drilled holes are required in the manufacture of almost every product and drilling is one of the most common machining operations. Drilling machines are similar in construction to milling machines except they are used exclusively for making holes.

All drilling machines are characterized by a rotating cutting tool which advances along its axis into a stationary workpiece producing a hole. Six common operations which can be performed on a drill press are drilling, reaming, boring, counterboring, countersinking, and tapping. Drilling machine capacity is determined by the size of the largest workpiece over which the spindle can be centered, the maximum clearance under the spindle, and the maximum drill diameter which can be fed at a practical feed rate through mild steel. The five major classifications of drilling machines are uprights, radials, horizontals, turret drills, and multiple-spindle machines. Each classification represents a family of machines which is further subdivided.

Upright drills comprise the largest group and are characterized by a single vertical spindle rotating in a fixed position and supported in a modified C-frame structure. The major components of the upright drill include the base, column, spindle, motor, head, table, feed mechanism, and quill.

Radial drills are designed to accommodate large work. These machines are arranged so that the spindle can be positioned to drill anywhere within reach of the machine by means of movement provided by the head, the arm, and the rotation of the arm about the column. Some types of radials and portable horizontal machines allow the entire machine to be moved to the workpiece.

Horizontal drills are characterized by the position of the spindle. Way-type and spindle-feed horizontals are self-contained units consisting of motor drive, gearing, and spindle which may be mounted at any predetermined drill angle and are used extensively to meet high production needs.

Turret drilling machines provide a number of tools mounted in a turret designed to handle a sequence of operations. The turret drilling machine is also available as a computer numerically controlled machine.

Multiple-spindle drilling machines include those designed with fixed spindles for single-purpose production and those where the spindles are adjustable, either by means of universal joints or by traversing along a worm or spiral drive in a straight line. Multiple-spindle drilling machines are primarily used for high production rate workpieces.