Radial Drill Explained

The radial drill is a machine tool that can be used for various operations such as drilling, enlarging, reaming, tapping, and facing end faces.

Radial Drill

According to the classification of machine tool clamping structures, radial drills can be divided into hydraulic and mechanical types.

Among all drilling machines, radial drills are known for their ease of operation, versatility, and widespread use. They are particularly suitable for single-piece production or mass production of holes in large workpieces. Radial drills are a common machine tool found in general machining workshops.


A radial drilling machine, also known as a cross arm drill, is a machine used for drilling holes into larger and heavier workpieces. The headstock of the machine can be moved left and right and rotated ±180° on the rocker arm. The rocker arm can also be adjusted up and down along the outer column to accommodate workpieces of different heights.

Smaller workpieces can be mounted on the workbench, while larger workpieces can be placed directly on the machine base or the floor. Radial drilling machines are commonly used in single and small batch production. They are available in a wide range of screw holes, threaded bottom holes, and oil holes to accommodate various drilling needs.

There are two main types of radial drilling machines: sliding seat type and universal type. The sliding seat type is formed by changing the base of the basic rocker drilling machine into a sliding seat, which can be moved along the bed rail for increased processing range. This type is suitable for use in the boiler, bridge, rolling stock, shipbuilding, and machining industries.

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The universal radial drilling machine has additional horizontal movement capabilities in addition to vertical and rotary motion. The spindle head can also be tilted on the rocker arm to adapt to the machining of different parts of the workpiece. Additionally, there are turning, wall, and digital control rocker drilling machines available.

The main structure

The radial drilling machine is composed of several key components, including a base, an inner column, an outer column, a rocker arm, a headstock, and a workbench. The inner column is securely attached to the base, while the outer column is fitted over the outer side of the inner column and can rotate 360 degrees around it.

The rocker arm is designed with a sleeve that fits over the outer column, allowing it to move up and down. The screw rod is integrated with the outer column and the lifting nut is fixed to the rocker arm, preventing the rocker arm from rotating around the outer column. It can only rotate around the inner column in conjunction with the outer column.

The headstock is a complex component that consists of several key components, including the main drive motor, the spindle and spindle drive, the feed and shift mechanism, and the machine’s operating mechanism. It is mounted on the horizontal rail of the rocker arm and can be moved along the rail by turning the handwheel.

Movement form

During machining, the headstock is securely attached to the rocker rail using a special clamping device. The outer column is also attached to the inner column, and the rocker arm is attached to the outer column. Then, the drilling process begins.

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The drill bit performs a longitudinal feed while rotating to cut the material. The three main movements of the radial drilling machine during the drilling process are:

(1) The main motion is the rotary motion of the main shaft.

(2) The feed motion is the longitudinal feed of the spindle.

(3) The auxiliary movement involves the rocker arm moving vertically along the outer column, the headstock moving along the length of the rocker arm, and the rocker arm rotating around the inner column together with the outer column.

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