Radial Drilling Machine – Parts, Construction and Working

Radial Drilling Machine is used to drill medium to large and heavy workpieces. This machine is used to drill holes in the given radial distance. It is mainly used when the component size is large in height.

Radial Drilling machine is mainly made for drilling holes in heavy jobs or workpieces. Since heavy jobs cannot move much, so the radial drilling machine is made in such a way that the tool of the machine can move any part of the heavy job without moving the job much.


Radial Drilling Machine
Radial Drilling Machine

Parts of a radial drilling machine:-

1) Base
It is the bottommost part of the radial drilling machine. It is made up of cast iron because cast iron has high compressive strength. The base is used to support the assembly of parts on it. It also absorbs the vibrations and shocks induced by the machine parts.

2) Column
The column is present at one end of the base. It is a vertical pillar which act as support for rotating the radial arm in 360 degrees.

3) Table
It is mounted above the column. It is provided with T slots for mounting the workpiece directly on its face. It is usually round or rectangle in shape.

4) Radial Arm
This is the part which is connected to the column. This part can rotate 360 degrees around the column. The face of the radial arm is accurately machined and drill head slides over it. This arm goes up and down in the column. In big machines, hydraulics are used to move the arm up and down.

5) Drill Head
Drill Head is mounted on the radial arm and drives the drill spindle.
It encloses all the mechanism for driving the drill at a different speed and feeds.

6) Spindle
It is the part of the drilling machine that holds the tool of drilling machine and is responsible for its rotation.

7) Motor
The motor is present at the top of drill head which drives the horizontal spindle.

8) Chuck
Chick is present at the bottom of the spindle. It is used to hold the drill bit in its place.

9) Tool or Drill Bit


Drill Bit is used to drill the holes in the workpiece. It is the part that rotates and enters into the workpiece making a hole.

Construction of Radial Drilling Machine :-

The bottommost part of the radial drilling machine.It is generally made of cast iron as cast iron has high compressive strength. On top of base the column is present. It is cylindrical in shape. The radial arm moves up and down in the column and it can also rotate in the column.

The table is placed above the base where the workpiece can be held for the drilling process.

The radial arm has a drill head. Different parts like spindle, chuck and motor for rotation of drill bit is present in this drill head. Motor is present above the head which rotates the spindle.

The spindle is attached to the drill head and chuck is present below the spindle. In the chuck, the drill bit is fixed which is used to make hole in the workpiece by rotating it and feeding it into the workpiece.

Working of Radial Drilling Machine

At starting when the power supply is given, the spindle rotates which is driven by the motor. As the radial arm can move up and down in the column, so radial arm is adjusted according to the operation and the height of the workpiece.
The spindle is connected to the chuck and the drill bit is placed in the jaws of the chuck.
The head of the drilling machine is also adjusted so that the tool is in the right position to make the hole in the workpiece. After that a suitable feed is given and then the drill bit drives into the workpiece with ease.

The drive mechanism used in a drilling machine is Rack and Pinion Mechanism.

In Rack and Pinion Mechanism, gears are used to convert rotation into linear motion. When the hand wheel is rotated, then the Pinion which is attached to the rack also rotates which converts rotation into linear motion and hence the drill bit moves towards the workpiece.

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