Drilling machine

Name Harshal Bhatt
Department Mechanical 2nd year

Department Mechanical
Semester 3rd
Batch C -1
Faculty Name Nayan Mistry

3
Drilling is the process of cutting holes in
metals by using a drilling machine as shown
Drills are the tools used to cut away fine
shavings of material as the drill advances in a
rotational motion through the material.
Drilling is done by forcing a rotating drill into
stationary job as on a drilling machine or by
forcing stationary drill in a rotating workpeiece
as on a lathe.
Drilling also done by milling machine with a
drilling attachment. In this case the job is fed
onto rotating drill.

 Types of drilling machines:
1. Portable drilling machine
2. Upright drilling machine
3. Sensitive drilling machine
4. Radial drilling machine
5. Gang drilling machine
6. Multi-spindle drilling press
7. Automatic drilling machine
8. Turret drilling machine
9. Numerically controlled drilling machine

 This type of drilling machine is can carried anywhere in shop.
So it is called portable.
 The machine can be used for creating holes with work piece in
any position which is not possible with standard drilling
machines.
 The entire machine is quite compact and handy.
 Most of the portable drilling machines are operated by
individual motors contained in the machine. Some small
machines can be operated by hand.

 The column may be round or of box
section.
 It can be raised or lowered along the pillar
depending upon the height of the job
clamped in position for rigidly.
 The table in the case can be rotated about
its own axis and clamped in position.
 The swivel of the table about the pillar and
rotation of the table about its center permits
easy location of the job under the drill.

 A Gang drill machine has a number of drill
heads arranged with a common base and
table.
 Each drill head has its own power unit and
carries a tool to perform an operation on a
job in sequence.
 The spindle may be set up with drills of
different diameter or other tools as required.
 The job is moved from one spindle to the
other spindle for performing various
operations.
 Gang drilling machines are useful when
several different machining cuts with
different tool are to be taken on sufficiently
large number of work pieces.

 Multi-spindle drilling machines with two
or more spindles driven by a common
head.
 This machine are used for drilling a
numbers of holes simultaneously in a
work piece.
 Multi-spindle machines are high
production rate machines and lead to
considerable saving for large quantity
jobs.

 These are high performance automatic
machine designed for variety of operations
being done on the work piece.
 A number of machines are arranged in series
to perform variety of different operations on
the work piece at successive work stations.
 After one operation is completed at one
workstation the work piece is automatically
transferred to the next work station.
 Because all operation are done automatically
the preciseness is higher and production time
is lower.

 A drill bit is a multi-point tool and typically has a pointed end. A twist
drill is the most common type used.
 Twist drills are available with parallel shanks up to 16mm diameter
and with taper shanks up to 100mm diameter
 Standard lengths are known as jobber-series twist drills, short drills
are known as stub series, and long drills as long series and extra long
series.
 Different helix angles are available for drilling a range of materials.
 Manufactured from three main materials
1. Carbon-tool steels
2. High-speed steel
3. Cemented-carbide

Twist Bit
Brad Point Bit
Auger Bit
Plug Cutter
Glass /
Tile Bit

Installer Bit
Self-Feed
Bit
Spade Bit Hole Saw
Forstner Bit

It is classified as follow:
1. Drilling
2. Reaming
3. Boring
4. Counter boring
5. Counter sinking
6. Spot facing
7. Tapping
8. Trepanning

 Drilling is the operation of producing
circular holes in solid metal by rotating
the drill and feeding it through the job.
This is the main operation done on the
this machine.
 Before starting the drilling it is necessary
to mark the position of the hole on the
work piece.
 Drilling process is dose not produce
accurate hole. The center may not be
accurate, the size of the hole is slightly
larger than required.

 Reaming is an operation of sizing and shaping a
hole using a tool called reamer.
 A reamer as shown on figure is multitoothed tool
designed for remove relatively small amount of
material from a previously drilled hole.
 Reaming is done to achieve accurate hole
dimension.
 Initially a hole is drilled slightly smaller in size.

 Boring is a process of aligning, sizing and
finishing a cylindrical hole.
 It uses single point cutting tool which
rotates relative to the stationary work piece.
 The hole can be aligned and sized with
good surface finish.
 Boring is often used to enlarge the drilled
holes.

• Counter boring is the operation of enlarging one
end of an existing hole concentric with the original
hole with a square bottom as shown in figure.
• The counter tool known as counter bore has a pilot
as shown in figure.
• The pilot enters in previously drilled hole and align
the tool so that the counter bored hole is concentric
with the existing hole.
• The tool has end cutting edges square with the axis
to produce a flat bottom.
• Counter boring is used to recess a bolt head or a
nut below the surface to permit a mitting part to
operate with obstruction.

 A countersink tool enlarges
the top portion of an existing
hole to a cone-shaped opening.
 Countersinking is performed
after drilling to provide space
for the head of a fastener, such
as a screw, to sit flush with the
work piece surface.
 Common included angles for a
countersink include 60, 82, 90,
100, 118, and 120 degrees.

 Spot facing shown in figure is the process of
producing a flat machined surface generally
around a hole perpendicular to the hole axis.
 This flat surface allows the bottom of a
screw or bolt to seat squarely with the
material.
 Spot facing is commonly done on castings
where irregular surfaces are found.
 Spot facing may be performed on a drill
press with a counter bore of suitable size for
the operation.

 Tapping is a thread cutting for producing
internal threads.
 Tapping uses multi- point cutting tool called
taps may be done manually or on machine
like drills.
 The tapping attachment used with the drill
permits forward rotation of the tap when it is
cutting and fast reverse rotation for
withdrawal.

 Trepanning is the process for making
large holes in sheet metal.
 A small diameter hole is drilled in
center for drilling large diameter hole.
 The pilot of trepanning tool is fitted
into this hole and the length of the
adjustable arm is set to the radius of
the hole to be cut.
 Holes up to a diameter of 350 mm
can be cut by this arrangement.

 The classification is as follow:
1. Machine Table Vice
2. Step Blocks
3. Clamps
4. V-Blocks
5. Angles
6. Jigs
7. T- Slots Bolt

Cutting Speed (v):-
It’s the peripheral speed of the drill
v = *D*N where
D = dia of the drill in m
N = Speed of rotation in rpm
Feed Rate (f):-
It’s the movement of drill along the axis (rpm)
Depth of Cut (d):-
The distance from the machined surface to the drill
d = D / 2

Material Removal Rate:-
It’s the volume of material removed by the drill per unit
time
MRR = ( D2 / 4) * f * N mm3 / min
Machining Time (T) :-
It depends upon the length (l) of the hole to be drilled ,
to the Speed (N) and feed (f) of the drill
t = L / f N min

 Do not support the workplaces by hand. Use a holding device to
prevent the work piece from being tom from the operator’s hand.
 Never make any adjustments while the machine is operating.
 Never clean away chips with your hand. Use a brush.
 Keep all loose clothing away from turning tools.
 Make sure that the cutting tools are running straight before starting
the operation

Drilling machine

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Drilling machine