all about drilling machines for the subject machine tools and digital manufacturing

1. Drilling Machine

2. Drilling machine
• A power operated machine tool which holds
the drill in its spindle rotating at high speeds
and when actuated move linearly against the
work piece produces a hole.

3. What is Drilling
• Drilling is the process
of cutting holes in
metals by using a
drilling machine and
a drill

4. Drilling
• 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.

5. Belt drive system
Motor spindle
Belt
Quill
Spindle
Rack & Pinnion
Feed lever

6. Types of drilling machine.
• Portable drilling machine
• Sensitive drilling machine
• Radial drilling machine
• Upright drilling machine
Depending on design, construction and use

7. Portable drilling machine

8. Sensitive Drilling Machine
• Drill holes
from 1.5 to
15mm
• Operator
senses the
cutting action
so sensitive
drilling
machine

9. Bench drilling machine
• These are light duty machines used in small
workshops.
• Also called Sensitive drilling machines because
of its accurate and well balanced spindle.
• Holes of diameter 1 mm to 15 mm.

10. Upright Drilling Machine
• Drill holes
upto 50mm
• Table can
move
vertically and
radially
• Box column
and round
column types

11. Radial Drilling Machine
• It the largest
and most
versatile
used fro
drilling
medium to
large and
heavy work
pieces.

12. Radial drilling machine
• These are heavy duty and versatile drilling
machine used to perform drilling on large and
heavy work piece.
• Holes up to 7.5 cm.

13. Hand Drill

14. Pistol-grip (corded) drill
• A drill in the shape of a
pistol.
• Commonly called
electric hand drill.

15. Cordless drills
• A cordless drill is a type
of electric drill which
uses rechargeable
batteries.

16. parts
• Vertical main column
• Base
• Moving drill head
• Work table
• Electric motor
• Variable speed gear box
and spindle feed
mechanism.

18. parts
• Column
– supports radial arm, drill head and motor
– Raise or lower the arm by elevating screw mechanism
• Radial arm
– Raise or lower to accommodate workpiece of different
height
– May be swivelling around the column
• Drill Head
– Carries drill spindle and drill bit
– Mechanism for rotating and feeding the drill
– Can be moved horizontally to position
• Work table
– Made of cast iron

19. Types based on movement of radial
arm and tool head
• Plain radial drilling machine
– Vertical adjustment of arm
– Horizontal drill head movement along the arm
– Circular movement of arm about vertical column
• Semi universal drilling machine
– Fourth movement
– Drill can be swung about horizontal axis perpendicular to arm
• Universal drilling machine
– Fifth movement
– Radial arm rotates about horizontal axis

20. Workholding

21. Work Holding Devices
• T bolts and Clamps
• Step Blocks
• V-Blocks
• Angle plate
• Drill Jigs
• Drill press vise

22. Direct Clamping
Clamping set

23. Step blocks
• In conjunction with t
bolts and clamps
• Support to other end of
clamp
• Steps for levelling
according to height of
work
• Made of mild steel

24. V Blocks & Clamps
• used when drilling
round bar

25. Angle plate
• made from high quality
material stabilized to
prevent further
movement /distortion.
• Slotted holes or T bolt
slots to enable clamping
of workpieces to the
plate, and the plate to
the worktable.

26. Drill jigs
• For mass production
• Hold the work securely,
locate the work and
guide the tool.
• Can be clamped and
unclamped quickly
• Special design according
to work

27. Drilling Machine Vice
• The Machine Vice has
slots in the side of the
base of the vice which
enable the user to
screw the Machine Vice
to the Drilling Machine
table.

28. Drill Materials
The two most common types are
1. HSS drill
- Low cost
2. Carbide- tipped drills
- high production and in CNC

29. Drill Bit
• A drill bit is a multi-point tool and typically
has a pointed end. A twist drill is the most
common type used

30. Drill Bit
• Flutes are incorporated to carry away the
chips of metal.
• Shank- provide the drive. Can be tapered or
parallel
• Body- tapers slightly in diameter from tip to
shank to provide clearance

31. Drill Bit
Fit in chuck
Fit direct into spindle

32. Twist drill
• Twist drills are available with parallel shanks up to
16mm diameter and with taper shanks up to 100mm
diameter and are made from high-speed steel.
• Different helix angles are available for drilling a range
of materials

33. Tool Holding

34. Tool Holding devices
• 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 chuck
• By socket

35. Drill fixed to the spindle

36. Tool Holding
Holding taper shank drills

37. 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

38. • Key-type
• Most common
• Tighten with key
• Different size keys for different size chucks

39. • Keyless
• Chuck loosened or tightened by hand
without key
• Precision keyless
• Holds smaller drills accurately

40. The Drill Chuck
Chuck
Morse Taper
Chuck Key
Keyless
Chuck

41. Sleeves
• Where a cutting tool or chuck has a Morse taper
smaller than that of the spindle, the difference is
made up by using a sleeve.
• Morse Taper Sleeve
• For example, a drill with a No. 1 Morse-taper shank
to be fitted in a spindle with a No. 2 Morse taper
would require a 1—2 sleeve.

42. Drill Socket
• Used when hole in spindle of drill press too
small for taper shank of drill
• Used often as extension sockets

43. Drill Drift
• To remove a shank from the spindle, a taper key known as a drift is
used.

44. Using the drill drift
• The drift is inserted through a slot in the spindle
Strike here
to remove
Most modern machines
have a built-in drift

45. Twist drill Nomenclature

46. The nomenclature of the twist drill is shown

50. Twist drills - Helix Types
• The helix angle of the twist drill is the
equivalent of the rake angle on other cutting
tools and is established during manufacture.
• The standard helix angle is 30 degrees, which,
together with a point angle of 118°, is suitable
for drilling steel and cast iron.

51. Helix types
Standard quick helixslow

52. Helix types
• Drills with a helix angle of 20° — known as slow-helix
drills — are available with a point angle of 118° for
cutting brass and bronze and with a point angle of
90° for cutting plastics materials.
• Quick-helix drills, with a helix angle of 40° and a
point angle of 100°, are suitable for drilling the softer
materials such as aluminium alloys and copper

53. Drilling Processes

54. Drilling operations…
• Operations that can be performed in a
drilling machine are
 Drilling
 Reaming
 Boring
 Counter boring
 Countersinking
 Tapping

55. Operations in drilling machine

56. Operations in drilling machine

57. Counter bore and spot facing

58. Typical Drilling Processes

59. Reaming
• A reamer enters the workpiece
axially and enlarges an existing hole
to the diameter of the tool.
• A reamer is a multi-point tool that
has many flutes, which may be
straight or in a helix.
• Reaming removes a minimal
amount of material and is often
performed after drilling to obtain
both a more accurate diameter and
a smoother internal finish.

60. Reaming

61. Countersinking
• 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
workpiece surface.
• Cutting speed = half of the
cutting speed of drilling for same
hole.

62. Countersinking
• Common included angles for a countersink include
…

63. Counterboring
• A counterbore tool enlarges
the top portion of an existing
hole to the diameter of the tool.
• Counterboring is often
performed after drilling to
provide space for the head of a
fastener, such as a bolt, to sit
flush with the workpiece
surface.
• The counterboring tool has a
pilot on the end to guide it
straight into the existing hole

64. Counter boring
• Cutting speed = two-
thirds of the drilling
speed for the same
hole.

65. Counterboring Bit

66. Spotfacing
• Spotfacing provides a seat or flat surface at the
entrance and surrounding area of a hole.
• This flat surface allows the bottom of a screw or bolt
to seat squarely with the material.
• Spotfacing is commonly done on castings where
irregular surfaces are found.
• Spotfacing may be performed on a drill press with a
counterbore of suitable size for the operation.
• A proper size pilot must be used whenever this is
done on the drill press.

67. Spot facing
• It is a finishing
operation to produce
flat round surface
usually around a drilled
hole, for proper seating
of bolt head or nut.
• It is done using a special
spot facing tool.

68. Spotfacing
spotface
Making a sloped
surface flat
Back
spotface

69. Spotting
• Where holes in two parts are required to line
up with each other, a technique known as
‘spotting’ is carried out. The top part is
marked out and drilled.
• The two parts are then carefully positioned
and clamped together.

70. The holes in the bottom part are transferred by ‘spotting’
through from the top part.
Drilling of the bottom part can then proceed in the knowledge
that both sets of holes are identical, which may not be the case
if both parts are marked out and drilled individually.
Spotting

71. Boring
• It is process carried on a
drilling machine to
increase the size of an
already drilled hole.
• Initially a hole is drilled to
the nearest size and using
a boring tool the size of
the hole is increased.

72. Tapping
• Process of cutting
internal threads with a
thread tool called tap.

73. Pilot Drilling
• Pilot hole is a smaller hole drill before a large
one.

75. Drilling holes to depth
• Holes can be
drilled to a
particular depth
by setting the
depth stop on
the machine
e.g. 15mm

76. Drilling Thin Material
Support acts as thicker material so drill point is guided through work

77. Cutting speed
• Cutting speed for drilling is the rate at which the
tool passes over the surface of the metal. i.e how
fast the cutting tool is spinning . It is commonly
expressed in metres per minute.

78. • Cutting speeds depend on:
The material being cut
Condition and strength of the tool and machine
Depth of cut
Rate of feed
Material of which the tool is made
Availability of cutting fluid
Size of the bit being used

79. Cutting speed selection
• The softer the work material, the faster the
recommended cutting speed

80. • The hardness of the cutting tool material has a
great deal to do with the recommended cutting
speed. The harder the cutting tool material, the
faster the cutting speed. The softer the cutting
tool material, the slower the recommended
cutting speed

81. Calculating cutting speed
• Given in metres per minute
• spindle speed of machine (N) and diameter
of work must be known
• S (m/min)= πDN/1000
• Where π= 22/7 or 3.142
• D= diameter of material
• N= Spindle speed(rev/min)
47-81

82. Spindle Speed
• The rate at which the spindle rotates. It is
commonly expressed in revolution per
minute.

83. Calculating Spindle speed (rev/min)
D
xS1000
rev/min
π
=
S (m/min)= cutting speed
Where π= 22/7 or 3.142
D= diameter of material
N= Spindle speed(rev/min

84. Examples
• Calculate rev/min required to drill a hole
15mm diameter in a piece of machine steel
(CS 90)
• Find the cutting speed of a 10mm diameter
drill with a spindle of 178 rev/min.

85. 5. Find the cutting speed for:
 Diameter 9mm. Spindle speed 180rev/min
 Diameter 6mm. spindle speed 20rev/min
 Diameter 5mm. spindle speed 160rev/min
• spindle speed 120 rev/min. Diameter 10mm.
6. Find the spindle speed for:
 Diameter 16mm. Surface speed 20 m/min
 Diameter 14mm. Surface speed 30 m/min
 Diameter 15mm. Surface speed 15 m/min.