drilling and boring machines

1. UNIT-III(B)
DRILLING AND BORING MACHINES
By
D. Kanaka Raja
Department of mechanical engineering,
AITS

2.  Drilling is the operation of producing circular hole in the work-piece by
using a rotating cutter called DRILL.
 The machine used for drilling is called drilling machine.
 The drilling operation can also be accomplished in lathe, in which the drill
is held in tailstock and the work is held by the chuck.
 The most common drill used is the twist drill.
 It is the simplest and accurate machine used in production shop.
DRILLING

3. DRILLING MACHINE
 Drilling machine
 Spindle
 Turns drill to advance into work (hand or automatically)
 Work table
 Holds workpiece rigidly in place as hole drilled
 Used primarily to produce holes in metal
 Other operations: tapping, reaming, boring, counter boring,
countersinking, spot-facing

4. WORKING PRINCIPAL OF DRILLING MACHINE
 The rotating edge of the
drill exerts a large force
on the workpiece and
the hole is generated.
 The removal of metal in
a drilling operation is by
shearing and extrusion.

5. SPECIFICATIONS OF DRILLING MACHINE
 Size of drilling table.
 Largest bit the machine can held.
 Maximum size of the hole that can be drilled.
 Maximum size the work piece that can be held.
 Power of the motor, spindle speed or feed.

6. TOOL NOMENCLATURE

7. TOOL NOMENCLATURE

8. TOOL NOMENCLATURE

9. TOOL NOMENCLATURE

10. TOOL NOMENCLATURE

11. TYPES OF DRILLING MACHINES
a) Based on construction:
Portable,
Sensitive or bench drilling machine
Radial,
up-right,
Gang,
Multi-spindle
Automatic
Turret
Deep hole
b)Based on Feed:
Hand and Power driven Portable drilling machine

12. PORTABLE DRILLING MACHINE
 It is a small light weight,
compact and self
contained unit that can
drill holes upto 12.5 mm
diameter.
 The machine is driven by
a small electric motor
operating at high speed.
 The machine is capable
of drilling holes in the
workpieces in any
position.

13. SENSITIVE OR BENCH DRILLING MACHINE
 These are light duty vehicles.
 Mounted on benches.
 To drill small diameter holes ,a twist drill
is fitted in the drill chuck.
 This design is used to drill hole from
1.5mm to 15mm diameter.
 The controls are light and delicate
speeds from 800 to 900 rpm are typical
range.

14. SENSITIVE DRILLING MACHINE

15. DRIVE MECHANISM IN SENSITIVE DM

16. UP-RIGHT DRILLING MACHINE
 Similar to sensitive drills have
power feed mechanism for rotating
drills and are designed for heavier.
 It is used for heavier work.
 Drill holes upto 50mm
 Table can move vertically and
radially

17. UP-RIGHT DRILLING MACHINE

18. RADIAL DRILLING MACHINE
 It the largest and most versatile
used fro drilling medium to large
and heavy work pieces.
 It can be radially adjusted
around the column in any
position over the work to get
different size and shapes of
work.
 The moments may be either
manual or power driven.
 The table is to be rotated
through 360 deg.
 The wide rang of power are as
well as sensitive and geared
manual feeds.

19. RADIAL DRILLING MACHINE
 This machine is used for drilling medium to large
heavy work pieces.
 Types of radial drilling machine.
1) plain radial drilling machine
2) semi universal drilling machine
3) universal drilling machine

20. RADIAL DRILLING MACHINE

21. DRIVE IN RDM

22. GANG DRILLING MACHINE
 When drilling spindles are mounted on a
single table, it is known as a gang drill.
 Each of these spindles can be
independently set for different speed
and depth of cut.
 Such machines are useful when number
of holes of different sizes are to be
drilled on the same work piece.
 Apart from drilling, a number of other
machining operations like reaming
counter boring, tapping etc can also be
performed at a time on this machine.

23. GANG DRILLING MACHINE

24. TURRET TYPE DRILLING MACHINE
 The stations are set up with a
variety of tools numerical control
is a also available.
 Two fixtures can be located side
by on the workable table, thus
permitting loading and
unloading of one part while the
other part is being machined
this reduces the machine cycle.

25. TURRET TYPE DRILLING MACHINE

26. DEEP HOLE DRILLING
 These machines are used for drilling holes
whose depth exceed normal drill size. These
machines are operated at high speed and low
feed.
 These machines are either horizontal or
vertical. The work or the drill may revolve.
most machines are of horizontal construction
using a center cut gun drill, which has a single
cutting edge with a straight flute running
througout its length.
 These machines are very useful for drilling
deep holes in rifle travels, crankshafts.

27. DEEP HOLE DM

28. DEEP HOLE DRILLING MACHINE
 Very deep holes of L/D ratio 6 to even 30, required for rifle barrels,
long spindles, oil holes in shafts, bearings, connecting rods etc, are
very difficult to make for slenderness of the drills and difficulties in
cutting fluid application and chip removal.
 Such drilling cannot be done in ordinary drilling machines and
bordinary drills.
 It needs machines like deep hole drilling machine such as gun drilling
machines with horizontal axis which are provided with

29. DRILLING OPERATIONS…
 Operations that can be performed in a drilling machine
are
 Drilling
 Reaming
 Boring
 Counter boring
 Countersinking
 Tapping and
 Spot Facing

30. DRILLING OPERATIONS…

31. OPERATIONS PERFORMED
 Drilling
 Operation of producing hole by
removing metal from solid mass
using twist drill
• Countersinking
– Operation of producing tapered
or cone-shaped enlargement
to end of hole

32. OPERATIONS PERFORMED
 Reaming
 Operation of sizing and producing
smooth, round hole from previously
drilled or bored hole
• Boring
• Truing and enlarging hole by
means of single-point cutting tool

33. OPERATIONS PERFORMED
 Tapping
 Cutting internal threads in hole
with cutting tool called tap
• Counterboring
– Enlarging top of previously
drilled hole to given depth
to provide square shoulder for
head of bolt or capscrew

34. OPERATIONS IN DRILLING MACHINE

35. COUNTER BORE AND SPOT FACING

36. OPERATIONS IN DRILLING MACHINE

37. TOOL HOLDING DEVICES
 Tool-holding devices are Used to hold or drive cutting tool
 The different methods used for holding drill in a drill spindle are
 By directly fitting in the spindle hole.
 By using drill sleeve
 By using drill socket
 By using drill chuck

38. TOOL-HOLDING DEVICES
 Drill press spindle provides means of holding and
driving cutting tool
 End may be tapered or threaded for mounting drill
chuck
 Most common
 Drill chucks
 Drill sleeves
 Drill sockets

39. DRILL FIXED TO THE SPINDLE
Drilling operations
Drilling Centre Hole
Drilling Deep Holes
Drilling Thin
Material
Drilling Pilot Hole

40. DRILL CHUCKS
 Most common devices used for holding straight-
shank cutting tools
 Most contain three jaws that move simultaneously
when outer sleeve turned
 Hold straight shank of cutting tool securely
 Two common types
 Key
 Keyless

41. WORK HOLDING DEVICES

42. WORK HOLDING DEVICES

43. WORK HOLDING DEVICES

44. CHUCKS
 Hold straight-shank drills
 Mounted on drill press spindle
 Taper
– Threads
• Held in spindle by self-holding
taper in larger machines
• Four types of drill chucks

45. TYPES OF DRILL CHUCKS
 Key-type
 Most common
 Three jaws move simultaneously
when outer sleeve turned
 Tighten with key
 Keyless
 Chuck loosened or tightened by
hand without key
 Precision keyless
 Holds smaller drills accurately

46. DRILL CHUCKS

47. TOOL HOLDER

48. DRILL TYPES

50. DRILL TYPES

53. TYPES OF CUTTERS
Reamers :-
Multi tooth cutting tool
Accurate way of sizing and finishing the pre-existing
hole.
Accuracy of 0.005mm can be achieved
Boring Tool:-
Single point cutting tool.
Boring tool is held in the boring bar which has the shank.
Accuracy of 0.005mm can be achieved.

54. TYPES OF CUTTERS
Countersinks :-
Special angled cone shaped enlargement at the end of the
hole Cutting edges at the end of conical surface.
Cone angles of 60°, 82°, 90°, 100°, 110°, 120°
Counter Bore Tool:-
Special cutters uses a pilot to guide the cutting action .
Accommodates the heads of bolts.

55. TYPES OF CUTTERS
Combined Countersinks and central drill :-
Special drilling tool to start the hole accurately.
At the end it makes countersinks in the work piece.
Gun drill :-
Machining of lengthy holes with less feed rates.
To overcome the heating and short life of the normal drill
tool

56. TYPES OF CUTTERS
Tapping:-
 For cutting internal
thread
 Multi cutting edge tool.
 Tapping is performed
either by hand or by
machine.
 Minor dia of the thread is
drilled and then tapping
is done.

57. Drilling And Drills
Types of drills
– Twist drill: most
common drill
– Step drill:
produces holes
of two or more
different
diameters
– Core drill: used
to make an
existing hole
bigger

58. WORK HOLDING DEVICES

59. WORK HOLDING DEVICES
 1. Machine Table Vice

60.  Step Blocks
 Clamps
 V-Blocks
 Angles
 Jigs
 T- Slots Bolt
WORK HOLDING DEVICES

61. DRILL MATERIALS
The two most common types are
1. HSS drill
- Low cost
2. Carbide- tipped drills
- high production and in CNC machines
Other types are
Solid Carbide drill, TiN coated drills, carbide coated
masonry drills, parabolic drills, split point drill

62. GRINDING OF DRILLS

63. GRINDING OF DRILLS

64. PARAMETERS DEFINITIONS
 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 axis
d = D / 2

65. 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

71. REAMING

86. 86
WHAT IS MEANT BY BORING?
 Boring is the process of
enlarging an existing drilled
holes with a single point cutting
tool.
 Boring operation can be
performed on engine lathe
Fig.1

87. CLASSIFICATION OF BORING MACHINE
 Horizontal boring machine ( production machines)
i. Table type HBM
ii. Planer type HBM
iii. Floor type HBM
 Vertical boring machine( production machines)
 Jig boring machine

88. HORIZONTAL BORING MACHINE

89. HORIZONTAL BORING MACHINE

90. HORIZONTAL BORING MACHINE
 The table type or universal type is the most versatile and commonly
used horizontal boring machine.
 Bed a heavy and strong bed carries the entire load of different
parts, work piece and tool over it.
 Columns a two vertical columns, one on each end of the table.
 Head stock the head stock can be moved vertically along the main
column.
 Load bearing end support it supports the end of a long boring bar
and can be adjusted vertically along the end support column.
 Horizontal table it is mounted on a saddle and can be moved
horizontal forward and backward and side by moving the saddle.

91. HORIZONTAL BORING MACHINE

92. VERTICAL BORING MACHINE

93. VERTICAL BORING MACHINE

94. VERTICAL BORING MACHINE
 The parts whose length or height is than diameter are machined.
 The work is fastened on a horizontal revolving table and the cutting tool
or tools which are stationary , advance vertically into it as the revolves.
 Horizontal cross rail is carried on vertical sideways and carries the tool
holder slide or slides.
 Most machine also have a slide tool head.
 Vertical boring machine is sometimes called a rotary planer and its
cutting action on flat disc is identical with a planer.
 These machines rated according to their table diameter, vary in size
from 0.9 to 12m.

96. FLOOR TYPE BORING MACHINE

97. PLANER TYPE BM

98. MULTIPLE HEAD BM

99. TURRET TYPE BM

100. JIG BORING MACHINE
 Jig boring machine resembles in
appearance to a vertical milling
machine.
 Rugged enough for heavy cuts and
sensitive enough for light cuts.
 Essential for modern mass production
 The machining accuracy of jig boring
machine is very high, within a range
of 0.0025 mm.

101. 101
NEED OF JIG BORING MACHINE
Jig boring machines are mainly to perform machining operations
like
• Boring.
• Drilling.
• Reaming.
• Counter boring holes in metal jigs
• Counter-sinking holes in metal work pieces.
Some jig boring machines are used for accurately enlarging the
• Existing holes.
• Making their diameters highly accurate
 Boring can correct hole location, size, or alignment and
can produce a good finish if a fine feed and correct tool are
used.

102. 102
NEED OF JIG BORING MACHINE
 Jig boring can also maintain high accuracy between
multiple holes or holes and surfaces.
 Some jig boring machines are designed to machine holes
with the tightest tolerances possible with a machine tool.
 The constant demand for accuracy within many branches
of metalworking has been fulfilled with the help of
applications possible by jig-boring machines.

103. JIG BORING MACHINE
 Jig boring machines are used in precision tool room applications for
locating and boring holes in
• Jigs.
• Fixtures.
• Gauges.
• And other precision parts.
 To prevent the influence of ambient temperature on machining accuracy
 Jig boring machines should be installed in a special environmental
enclosures (i.e., in a temperature controlled rooms) with temperature
maintained at a level of 20 °C.
 Jig borers can be used as coordinate measuring machine for inspection and
precision layout operation .
103

104. Simple Jig Boring Machine
column
spindle head
quill
boring toolspindle
table
bed
saddle
Line DiagramFig.2
PARTS OF JIG BORING MACHINE

105. JIG BORING MACHINE
105
Fig.3

106. JIG BORING MACHINE
The main distinguishing features of these machines are :
 The spindle and other parts are rigid to prevent deflection.
 The spindle runs in preloaded ant frictional bearings.
 The spindle housing is made of material having very low co-efficient of
linear expansion .
 For boring, the work pieces are clamped on the table by T-bolts and
straps.
 an existing hole is enlarged by using a single point tool.
 The single point tool produces
• Better surface finish.
• And locates holes with maximum accuracy.
106

107. JIG BORING MACHINE
 ⎯ high spindle speed
 ⎯ high rigidity
 ⎯ tool guide
 ⎯ Pressurized cutting oil for effective cooling, chip
removal and lubrication at the drill tip.
 Deep hole drilling machines are available with both
hard automation and CNC system.

108. JIG BORING MACHINE
 The principle of boring using single point tool is illustrated
in fig.
108
Fig.4

110. PARTS OF JIG BORING MACHINE

117. CUTTING FORCES

118. KINEMATIC SYSTEM OF GENERAL PURPOSE DRILLING MACHINE
AND THEIR PRINCIPLE OF WORKING

119. KINEMATIC SYSTEM OF GENERAL PURPOSE
DRILLING MACHINE AND THEIR PRINCIPLE OF
WORKING
 Mechanisms to enable transform and transmit motion(s) from
the power source(s) to the cutting tool and the workpiece for the
desired machining action.
 a typical kinematic system of a very general purpose drilling
machine, i.e., a column drilling machine having 12 spindle
speeds and 6 feeds.
 The kinematic system enables the drilling machine the following
essential works;

120. KINEMATIC SYSTEM OF GENERAL PURPOSE
DRILLING MACHINE AND THEIR PRINCIPLE OF
WORKING
 Cutting motion:
 The cutting motion in drilling machines is attained by rotating the drill at different
speeds (r.p.m.).
 Like centre lathes, milling machines etc, drilling machines also need to have a
reasonably large number of spindle speeds to cover the useful ranges of work
material, tool material, drill diameter, machining and machine tool conditions.
 The drill gets its rotary motion from the motor through the speed gear box (SGB)
and a pair of bevel gears.
 For the same motor speed, the drill speed can be changed to any of the 12 speeds
by shifting the cluster gears in the SGB. The direction of rotation of the drill can be
changed, if needed, by operating the clutch in the speed reversal mechanism, RM-
s shown in the figure.

121. KINEMATIC SYSTEM OF GENERAL PURPOSE
DRILLING MACHINE AND THEIR PRINCIPLE OF
WORKING
 Feed motion
 In drilling machines, generally both the cutting motion and feed motion
are imparted to the drill. Like cutting velocity or speed, the feed (rate) also
needs varying (within a range) depending upon the tool-work materials
and other conditions and requirements.
 drill receives its feed motion from the output shaft of the SGB through the
feed gear box (FGA), and the clutch. The feed rate can be changed to
any of the 6 rates by shifting the gears in the FGB. And the automatic
feed direction can be reversed, when required, by operating the speed
reversal mechanism, RM-s as shown

122.  Tool work mounting
 The taper shank drills are fitted into the taper hole of the spindle
either directly or through taper socket(s).
 Small straight shank drills are fitted through a drill chuck having
taper shank.
 The work piece is kept rigidly fixed on the bed (of the table).
 Small jobs are generally held in vice and large or odd shaped
jobs are directly mounted on the bed by clamping tools using the
T-slots made in the top and side surfaces of the bed as indicated
KINEMATIC SYSTEM OF GENERAL PURPOSE
DRILLING MACHINE AND THEIR PRINCIPLE OF
WORKING