All About Drilling Machine

The Drilling Machine  blog is a comprehensive resource designed for engineering students, professionals, and anyone interested in machining and metalworking. It provides detailed answers to frequently asked questions on various aspects of drilling machines, from basic concepts to advanced techniques. Whether you're an aspiring engineer, a diploma student, or someone looking to refresh your knowledge, this blog covers all essential topics related to the drilling machine, its components, functions, operations, and types.

1.  Write short notes on drilling

Drilling can be called as the operation of originating a hole by rotating edges of a drill. The hole may be a through hole or blind hole.

The cutting tool known as drill is fitted into the spindle of the drilling machine. A mark of indentation is made at the required location with a centre punch. The rotating drill is pressed at the location and is fed into the work. The hole can be made unto a required depth.

2.  With a neat sketch explain the nomenclature of a drill

Body 

It is the part of the drill without its shank and neck. Helical grooves are cut on the body of the drill. 

Shank

It is the part of the drill by which it is held and driven. The shank may be straight or taper. The shank of the drill can be fitted directly into the spindle or by a tool holding device. 

Tang 

The flattened end of the taper shank is known as tang. It is meant to fit into a slot in the spindle or socket. It ensures a positive drive of the drill.

Neck 

It is the part of the drill, which is diametrically undercut between the body and the shank of the drill. The size of the drill is marked on the neck.

Point 

It is the sharpened end of the drill. It is shaped to produce lips, faces, flanks and chisel edge. The point angle for a normal grade drill is 118 degree.

Lip 

It is the edge formed by the intersection of flank and face. There are two lips and both of them should be of equal length. 

Land 

It is the cylindrically ground surface on the leading edges of the drill flutes adjacent to the body clearance surface. 

Flutes 

The grooves in the body of the drill are known as flutes. Flutes form the cutting edges on the point. It allows the chips to escape and make them curl. It permits the cutting fluid to reach the cutting edge.

3.  How to designate a drill ?

In Indian standard system a drill is designated as follows:

E.g., A parallel shank twist drill of long series, 10mm diameter, conforming to IS standard, made of carbon steel, of type S and point angle 80 is designated as:

Parallel shank twist drill (long) 10.00-IS : 599-CS- S- 80

Type

Drills are made in 3 different types namely:

Normal (N) with point angle 118⁰

Hard (H) and Soft (S)

Shank

Shank of the drill may be parallel shank or taper shank which generally depend on the size. Generally large size drills are made with taper shank and small sizes with straight shank.

Material of drill

Materials used for drills are :

Carbon Steel(CS)

High Speed Steel (HSS) and

Carbide tipped drills

4.  Explain different types of drilling machines

The different types of drilling machines are: 

1. Portable drilling machine (or) Hand drilling machine 

2. Sensitive drilling machine (or) Bench drilling machine 

3. Upright drilling machine 

4. Radial drilling machine 

5. Gang drilling machine 

6. Multiple spindle drilling machine 

7. Deep hole drilling machine

Portable drilling machine

Portable drilling machine can be carried and used anywhere in the workshop. It is used for drilling holes on workpieces in any position, which is not possible in a standard drilling machine.

Sensitive drilling machine

It is designed for drilling small holes at high speeds in light jobs. The base of the machine is mounted either on a bench or on the floor by means of bolts and nuts. The machine is named because of the reason that the operator can sense the progress of the drill into the work , as it is fed by hand.

Gang drilling machine 

Gang drilling machine has a long common table and a base. Four to six drill heads are placed side by side. The drill heads have separate driving motors. This machine is used for production work. A series of operations like drilling, reaming, counter boring and tapping may be performed on the work by simply shifting the work from one position to the other on the work table. Each spindle is set with different tools for different operations.

Multiple spindle drilling machine

 This machine is used for drilling a number of holes in a workpiece simultaneously and for reproducing the same pattern of holes in a number of identical pieces. A multiple spindle drilling machine also has several spindles. A single motor using a set of gears drives all the spindles. All the spindles holding the drills are fed into the work at the same time. The distances between the spindles can be altered according to the locations where holes are to be drilled.

Deep hole drilling machine

 A special machine and drills are required to drill deeper holes in barrels of gun, spindles and connecting rods. The machine designed for this purpose is known as deep hole drilling machine. High cutting speeds and less feed are necessary to drill deep holes. A non rotating drill is fed slowly into the rotating work at high speeds. Coolant should be used while drilling in this machine.

5.  With a neat sketch explain the parts of a sensitive drilling machine

It is designed for drilling small holes at high speeds in light jobs. The base of the machine is mounted either on a bench or on the floor by means of bolts and nuts. The machine is named because of the reason that the operator can sense the progress of the drill into the work , as it is fed by hand.

Base 

The base is made of cast iron and so can withstand vibrations. It may be mounted on a bench or on the floor. It supports all the other parts of the machine on it. 

Column 

The column stands vertically on the base at one end. It supports the work table and the drill head. The drill head has drill spindle and the driving motor on either side of the column. 

Table 

The table is mounted on the vertical column and can be adjusted up and down on it. The table has ‘T’-slots on it for holding the work pieces or to hold any other work holding device. The table can 

be adjusted vertically to accommodate work pieces of different heights and can be clamped at the required position. 

Drill head 

Drill head is mounted on the top side of the column. The drill spindle and the driving motor are connected by means of a V-belt and cone pulleys. The spindle can be moved up and down by a hand feed lever. The spindle rotates at a speed ranging from 50 to 2000 rpm.

6.  With a neat sketch explain the parts of an upright drilling machine

The upright drilling machine is designed for handling medium sized workpieces. Though it looks like a sensitive drilling machine, it is larger and heavier than a sensitive drilling machine. Holes of diameter up to 50mm can be made with this type of machine. It is also supplied with power feed arrangement. For drilling different types of work, the machine is provided with a number of spindle speeds and feed.

7.  With a neat sketch explain the radial drilling machine

The radial drilling machine is intended for drilling on medium to large and heavy work pieces. It has a heavy round column mounted on a large base. The column supports a radial arm, which can be raised or lowered to enable the table to accommodate work pieces of different heights. The arm, which has the drill head on it, can be swung around to any position. The drill head can be made to slide on the radial arm. The machine is named so because of this reason. 

The radial drilling machine may be Plain, Semi universal or Universal type. In a Semi universal type, the drill head can be tilted right or left to drill angular holes. In a universal type, the drill head can be tilted left or right and front or back to drill holes in a compound angle.

8.  How to specify a drilling machine ?

Drilling machines are specified according to their type. To specify the machine completely the following factors are considered: 

1.   The maximum diameter of the drill that it can handle 

2.   The size of the largest workpiece that can be centred under the spindle 

3.   Distance between the face of the column and the axis of the spindle

4.   Diameter of the table 

5.   Maximum travel of the spindle 

6.   Numbers and range of spindle speeds and feeds available 

7.   Morse taper number of the drill spindle 

8.   Floor space required 

9.   Weight of the machine 

10. Power input is also needed to specify the machine completely.

9.  Explain about work holding devices used in drilling machine

The devices used for holding the work in a drilling machine are 

1. Drill vice 

2. ‘T’ - bolts and clamps 

3. Step block 

4. V - block 

5. Angle plate 

6. Drill jigs 

10.  Explain about tool holding devices used in drilling machine

Different tools are used for performing different operations. They are fitted into the drill spindle by different methods. They are 

1. By directly fitting in the spindle 

 2. By a sleeve 

 3. By a socket 

 4. By a chuck 

 5. Tapping attachment

11.  Explain different tools used in drilling machine

Different tools are used for performing different types of operations. The most commonly used tools in a drilling machine are 

1. Drill 

2. Reamer 

3. Counter bore 

4. Countersink 

Drill 

A drill is a tool used to originate a hole in a solid material. A helical groove known as ‘flute’ is cut along the length of the drill. Different types of drills are 

 1. Flat Drill 

 2. Straight fluted drill 

 3. Twist drill 

 4. Centre drill 

twist drills are the type generally used in shop work. They are made of High speed steel (HSS) or High carbon steel. There are two types of twist drills namely 

(i) Straight shank twist drill and 

(ii) Taper shank twist drill. 

The diameter of the straight shank drill ranges from 2 to 16mm. Taper shanks is provided on drills of larger diameter.

Reamer 

The tool used for enlarging and finishing a previously drilled hole is known as a reamer. It is a multi tooth cutter and removes smaller amount of material. It gives a better finish and accurate dimension.

 

Counter bore 

A Counter bore is a multi tooth cutting tool used for enlarging the top of the previously machined hole. It has three or four cutting teeth. The flutes on them may be straight or helical. Straight fluted tools are used for machining softer materials like brass and aluminium and for short depth of cut. Helical fluted types are used for longer holes.

Countersink 

A countersink has cutting edges on its conical surfaces. It has a similar construction of a counter bore except for the angle of the cutting edges. The angle of countersinks will generally be 60°, 82° or 90°. It is used for enlarging the top of the holes conically.

12.  Explain different operations performed in drilling machine

Though drilling is the primary operation performed in a drilling machine, a number of similar operations are also performed on holes using different tools. The different operations that can be performed in a drilling machine are: 

 1. Drilling 

 2. Reaming 

 3. Boring 

 4. Counter boring 

 5. Countersinking 

 6. Spot facing 

 7. Tapping 

 8. Trepanning