drilling machine

1. Faculty of Engineering
Mechanical Engineering Department
Lecture No. (8)
‫ﻣﻌﺪﺍﺕ‬ ‫ﻭ‬ ‫ﺃﺳﺎﻟﻴﺐ‬‫ﺗﺸﻐﻴﻞ‬)1(
Machining Techniques & Equipment (1)
Dr. Rania Mostafa
Drilling Machine

2. ۲۲
Outline
 Introduction and drilling operation definition
Twist drill
Drilling operations and drill materials
Cutting and feed motions
Chip shape
Types of drilling machines
Main parts of drilling machine
 Work holding
Types of holes and its purpose
 Machining time calculations
 Accident Prevention

3. ۳۳
Introduction
 Drilling is the cutting 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.

4. ٤٤
 It is the simplest and
accurate machine
used in production
shop.
 A power operated
machine tool holds the
drill in its spindle
which rotates and
moves linearly against
the stationary work
piece to produce a
circular hole.
Drilling Machine

5. ٥٥
Drill press

6. ٦٦
Machine working
 Work piece with the exact location marked
on it with the centre punch is clamped rigidly
on the work table.
 spindle axis and center punch indentation
are in same line.
 Machine is started and drill bit is lowered by
rotating feed handle.
 Drill bit touches the work and starts
removing material.

7. ۷۷
The cutting speed will be
a maximum at either corner
(the outer radius of the major
cutting edge) and will be zero
at the tip of the drill, which is
in the form of the short chisel
edge.
The feed per tooth is the
depth of material removed by
each tooth and measured
parallel to the direction of
feed motion
Cutting speed and Feed

8. ۸۸

9. ۹۹
Twist Drill nomenclatures

10. ۱۰۱۰
Drill Construction
Drill can be defined as
a rotary end cutting tool
having one or more
cutting lips, and having
one or more helical or
straight flutes for the
passage of chips and
the admission of a
cutting fluid.
A twist drill is made
up of three main
components:
– Shank
– Body
– Drill point

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13. ۱۳۱۳
Drill Nomenclature

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16. ۱٦۱٦
 Drill Web is the thickness
measured across the base of
the flutes”
 It Contributes to the
torsional strength of the drill

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36. ۳٦۳٦
Twist drills are usually considered suitable for
machining holes having a length less than five times
their diameter.
Special drills are required for machining the deeper
holes.
Large twist drills are usually provided with taper
shank while the small ones will have a parallel shank.
The taper shank is designed to be inserted in taper
hole in the end of the spindle.
The tongue on the end of the shank is inserted in a
slot at the bottom of the hole in the spindle and
prevents rotations of the drill relative to the spindle
during machining.
The parallel shank is held in a three jaws chuck.

37. ۳۷۳۷
Taper and straight shank

38. ۳۸۳۸
Advantages of the twist drill
Diameters and spiral angles are retained to
the end
The chips are conveyed automatically out of
the drill hole by helical flutes.
Drilled hole purposes
 It takes up rivets, screws, bolts, shafts,
pistons and furthermore to pass through
gases, fluids, etc.

39. ۳۹۳۹

40. ٤۰٤۰
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

41. ٤۱٤۱

42. ٤۲٤۲
Drilling Operations

43. ٤۳٤۳
Types of drilling machine.
A wide variety of drilling machines are
available ranging from the simple portable to
highly complex automatic and numerically
controlled machines are as follows:
 Portable drilling machine
 Bench (sensitive) drilling machine
 Column type or drill press or up-right drilling
machine
 Radial drilling machine
 Pillar drilling machine
 Gang drilling machine
 Multiple drilling machine

44. ٤٤٤٤
1- Portable (hand) drilling machine
 It is a small light weight,
compact and self
contained unit that can
drill holes up to 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
work-pieces in any
position.

45. ٤٥٤٥
 These are light duty
machines used in small
workshops.
 Also called Sensitive drilling
machines because of its
accurate and well balanced
spindle.
 The machine has the
capacity to rotate Holes of
diameter 1 mm to 15 mm at
high speed of 20,000 rpm
2- Bench drilling machine

46. ٤۷٤۷
 Its main spindle is supported vertically and the
column holds the spindle, the main and feed
drives and the machine table.
 Table can move vertically and radially
 Drill holes up to 50mm
 Its disadvantage that while drilling deep holes,
the drill spindle emerges far from its bearings;
the drill can then easily run off centre.
3- Column drilling machine (drill press)

47. ٤۸٤۸
Up-right drill press

48. ٤۹٤۹

49. ٥۰٥۰
The main operating parts of
drill press/bench drill
1.Base:
The base is a heavy casting that supports
the machine structure;
It provides rigid mounting for the column
and stability for the machine.
 The base is usually provided with holes
and slots which help to Bolt the base to a
table or bench and allow the work-holding
device or the workpiece to be fastened to the
base.

50. ٥۱٥۱
2. Column:
The column is a vertical post that Column
holds the worktable and the head containing
the spindle and the driving mechanism.
The column may be of round or box section.
3. The drill spindle:
It takes up the drilling tool and it is guided
in a sleeve.
At the end of the spindle, toward the work
table, a taper hole is provided to fix the
drilling tools.

51. ٥۲٥۲
4. Drilling Head
The drilling head, mounted close to the top of
the column, houses the driving arrangement
and variable speed pulleys.
These units transmit rotary motion at different
speeds to the drill spindle.
The hand feed lever is used to control the
vertical movement of the spindle sleeve and the
cutting tool.

52. ٥۳٥۳
5. Table
 The table, either rectangular or round.
 Drill machine/press in shape supports the
work-piece and is carried by the vertical column.
The surface of the table is 90-degree to the
column and it can be raised, lowered and
swiveled around it.
 The table can be clamp/hold the required the
workpiece.
Slots are provided in most tables to allow the
jigs, fixtures or large work-pieces to be securely
fixed directly to the table.

53. ٥٤٥٤
 Heavy base
 Vertical
column
 Horizontal
arm
 Drilling head
4- Radial drilling machine

54. ٥٥٥٥
 It the largest and most versatile used for drilling
medium to large and heavy work pieces.
 The drill spindle head is carried by the arm and be
shifted in radial direction.
 The arm can be swung around the column and
adjusted in height.
 The work piece is clamped on the table which is
provided with T-slots.
• Power capacity is 1.5 hp for drilling motor and is 0.5 hp
for elevating motor.
• The range of speed of spindle is 50 to 2800 rpm.
4- Radial drilling machine

55. ٥٦٥٦
Work Holding for Drill Presses
• Work can be clamped in a vise, fixture, or jig:
Vise, general purpose work-holder with two jaws
Fixture, work-holding device that is usually
Custom, designed for the particular work
Drill jig, similar to fixture but also provides a
means of guiding the tool during drilling

56. ٥۷٥۷

57. ٥۸٥۸
Cutting Speed (v):-
It’s the peripheral speed of the drill
v = Π*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

58. ٥۹٥۹
Material Removal Rate:-
It’s the volume of material removed by the
drill per unit time
MRR = (Π 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

59. ٦۰٦۰
General Recommendations for
Speeds and Feeds in Drilling

60. ٦۱٦۱
Troubleshooting Guide for Drilling

61. ٦۲٦۲

62. ٦۳٦۳

63. ٦٤٦٤
Troubleshooting for Drilling

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65. ٦٦٦٦

66. ٦۷٦۷
Precautions for Drilling machine
 Lubrication is important to remove heat and
friction.
 Machines should be cleaned after use
 Chips should be removed using brush.
 T-slots, grooves, spindles sleeves, belts, pulley
should be cleaned.
 Machines should be lightly oiled to prevent from
rusting

67. ٦۸٦۸
Safety Precautions
 Do not support the work piece by hand – use work
holding device.
 No adjustments while the machine is operating
 Ensure for the cutting tools running straight before
starting the operation.
 Never place tools on the drilling table
 Avoid loose clothing and protect the eyes.
 Ease the feed if drill breaks inside the work piece.

68. ٦۹٦۹
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.

69. ۷۰۷۰
Reaming
 It is a process of
smoothing the surface
of drilled holes with a
tool.
 Tool is called as
reamer.
 Initially a hole is drilled
slightly smaller in size.
 Drill is replaced by
reamer.
 Speed is reduced to
half that of the
drilling.

70. ۷۱۷۱
Reaming

71. ۷۲۷۲
Reamer Geometry

72. ۷۳۷۳
Reamer Types

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