The drilling machine is defined as a machine which is used to make a circular hole, a tool used to drill the holes of different size and other related operations using a drill bit. The drilling machine is one of the most important machines in a workshop. As regards its importance it is second only to the lathe machines. Holes were drilled by the Egyptians in 1200 B.C. about 3000 years ago by bow drills.
Types of Drilling Machine
1- Portable Drilling Machine
These types of a drilling machine are commonly used in all the workshops. Used to drill small sized holes. It is operated by holding in a hand. The workpiece where the hole is to be drilled is held in a vice.
2- Sensitive Drilling Machine
This types of drilling machine used to drill small holes at high speeds in lighter jobs or workpieces. The machine may be mounted on the bench or floor and the drilling work is started with the drill fed into the workpiece by purely hand control.
Hand-feed permits the operator to sense the progress of the drill into the workpiece, so that if there is any drill worn out or jams it may be released immediately to prevent the drill bit from breaking. Since the operator senses the cutting action at any instant it is called as the sensitive drilling machine. These machines are capable of drilling small holes of diameter as small as 0.35 mm to 15 mm. These machines run at a higher speed as high as 2000 rpm.
3- Upright Drilling Machine
It is larger in size and stronger than sensitive drilling machine. It is used for drilling medium and large-sized holes. Based on the type of column used it is classified as a round column and box column upright drilling machines.
4- Radial Drilling Machine
The schematic diagram of the radial drilling machine is shown in the figure. It consists of the base, column radial arm, drill head, spindle speed and feed mechanism.
5- Gang Drilling Machine
This machine consists of the number of drill heads placed side by side so that more than one hole of same or different sizes can be drilled at a time on the same job or on different jobs.
The space between drill spindles is varied to suit the gap between the holes. This type of machine tool is used to drill a large number of holes in the same job at a faster rate. The main advantage of this type of machine tool is that the series of operation can be performed with different spindle mounted with different tool bits on the same workpiece by moving it from one position to another position.
6- Multi Spindle Drilling Machine
This machine tool is similar to a gang drilling machine in construction. It is used to drill the number of hole in the same workpiece simultaneously and to reproduce the same work in a number of similar jobs. All the spindle are driven by a single motor and fed continuously. During the feeding table with the workpiece is raised or lowered and the drill head position is not varied.
7- Automatic Drilling Machine
This types of drilling machine can perform a series of machining operations at successive units and transfer the work from one unit to the other automatically. Once the work is loaded at the first machine, the work will move from one machine to the other where different operations can be performed and the finished work comes out from the last unit without any manual handling. This type of machine is intended purely for production purposes and may be used for milling, honing and similar operations in addition to drilling and tapping.
8- Deep Hole Drilling Machine
This may be the either horizontal or vertical type of machine. In this drilling machine, the part to be drilled is rotated and the drill bit that makes the hole is kept stationary. Deep hole drilling is done in components like rifle barrels, crankshafts, long shafts etc.
