Boring Machine

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The boring machine is one of the vertalile machine tool used to enlarge already drilled hole. Boring operation can be performed on lathe as that of turning where tool is stationary and workpiece is rotating. But in case of boring is rotating and workpiece is stationary which is similar to Drilling ,reaming , milling etc. Boring machines can be classified based on position of boring tools, accuracy of work required etc.

Boring machines

1. Horizontal Boring Machine (HBM)

2. Vertical Boring Machine (VBM)

3. Precision (Jig) Boring Machine (PBM)


Horizontal boring machine contains the the majority of boring machines used in mass production. Here boring tool is rotating while the workpiece is stationary. Work piece is mounted on the table which can be moved with the help of crossslide and saddle.

Block diagram of horizontal boring machine

Important features of the horizontal boring machines are as following. Head Stock Column Runway End Support Table Saddle

(1) (2) (3) (4) (5) (6)


It is the most important part of a boring machine. It contains spindles. It supports, drives and feeds the boring tool. The spindle rotation is reversible for backing out tools. Boring tool is held in boring head which will be held in head stock.


Column supports head stock and tail stock. It guides up and down movement by means of ways. It is hollow and heavily constructed. To balance head stock and make it easy to move. Columns are keyed, dowelled and bolted to the base of the machine.



When ever the column is traversing the base used is known as runway. Main function of runways are to carry the main column, end support column and rotary table if any.




An out-board bearing is required to support the other end of the bar is known as end END SUPPORT COLUMN. End support column is necessary in case of long boring and heavy tools are used. There is an opened and closed type of end support.



Main function of the table is to support for holding the workpiece rigidly during the operation. Table is equipped with suitable ranges of feeds as well as quick reverse mechanism. Table moves perpendicular to the axis of the spindle.


The main function of saddle is to provide a compound movement of the table. This helps the table to move axially as well as transversly to the spindle.




Horizontal boring machine can be used to drill, bore ream holes. These are widely used in batch production where workpiece is less. These machine can also be used for machining type parts like gear boxes and engine blocks.


Schemating diagram of vertical boring machine is shown in figure. VBM will be used in case of length of the workpiece is less then the diameter.

Block diagram of vertical boring machine

Here the cutting tool is stationary and mounted in the tool head. Tool head can be moved linearly or upward and downward motion to reach near to the workpiece. The workpiece is mounted on the table which is rotating. Two columns are used to have rigid support to the tool head.


Vertical boring machine is used to machine inside and outside diameter. VBM can also be used in for facing large size workpiece. Different products are turbine casting, pressure vessels, tables for machine tools, gear blank etc. are machined on vertical boring machine.


Precision or Jig boring machine is used in high accuracy toolroom application. Different machine components include jigs, fixtures, gauges etc. Because of their high precision category they can also be used in precision coordinate measuring machines. Here the spindle bearing and spindle are constructed with very high accuracy. The table is mounted on cross-slide and saddle for compound movement of the workpiece.

The table can be moved precisely in two mutually perpendicular directions in a plan perpendicular to the spindle axis. Here tolerance upto 0.002mm can me maintained. These machines are costlier. Hence used only in big machine shops, where accuracy is required. These machines are also available with numerical control system. These machines are provided with various accessories.

Here the first one is the working pbm. The second picture shows the cross section of the pbm.