MET 103

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MET 103

• Dr. Salah Gasim Ahmed
• ACX F 92

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Module 2

• Drilling machines

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Drilling machines, or drill presses

• Drilling machines, or drill presses, are used
  for
• making holes and other operations.
• They are available in a wide variety of types and
  sizes.
• The most common types are
• Sensitive drill press
• Upright drilling machines
• Multiple spindle head drilling machine
• The radial drilling machine
• Gang drilling machine

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Bench Mounted Sensitive drill press
Floor Mounted Sensitive drill press
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1-Sensitive drill press

• Bench type
• Floor type
• They are designed for drilling holes
• up to ½ inch

Drilling head
Spindle
Table
Column
Base
press floor type
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Upright drilling machines

• Upright drilling machine is similar in design to
  the sensitive drill press but it has the
  following advantages
• It is larger and stronger than the sensitive type
• It is used for drilling large hole
• It has a gear drive mechanism to change the
  spindle speed
• It may have a mechanical device to raise the work
  table

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Floor Mounted Sensitive drill press
Up right drill press
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Drive System
variable-speed drive
stepped-vee pulley and belt
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The radial drilling machine
Radial arm
Drilling head
Spindle
Column
Table
Base
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The radial drilling machine

• The radial drilling machine is sometimes called
  the radial arm press. It has the following
  advantages
• It is used for large work
• Several holes can be drilled without moving the
  work piece
• It can accommodate various height of work
• The machine has more power, thus larger cutting
  tool can be used.
• On some models the drilling head can be swiveled
  so that holes can be drilled at an angle

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Gang drilling machine

• It is basically a series of single spindle drill
  presses mounted on a long table
• It is used for mass production
• It performs different drilling operations in
  sequence
• The work is moved along the table from a station
  to the next
• It eliminates the need for changing cutting tools

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Multiple spindle head drilling machine

• It is equipped with two or more heads
• Each head has several spindles
• It is used for production work only

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Machine Capacity

• Machine capacity is measured bythe diameter of
  work that can bedrilled.

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Spotting and Center Drills
Spotting drills are used to position holes
accurately for drilling with regular drills.

• Lathe center drills are often used as spotting
  drills.

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Twist drills
A twist drill is an end cutting tool used to
produce a hole in a piece of metal or other
material.
Straight shank up to ½ inch Taper shank
more than ½ inch
Body
Point
Shank
Flute
Margin
Clearance
The main parts of a twist drill
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Cutter holding device

• For straight shank
• Drilling chuck
• For Taper shank
• Sindle
• Sleeves

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Drill point angles

• For general purpose drilling
• Drill point angle 1180
• For hard materials
• Drill point angle 1350 -- 1500
• For soft materials
• Drill point angle 900

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Measuring the size of a twist drill

• It is a good practice to always check a drill for
  size before drilling a hole. Drill may be checked
  for size by two methods
• A drill gauge
• A micrometer or vernier
• Always be sure that the measurement is taken
  across the margin of the drill.

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Selection of the proper speeds

• Factors which affect the cutting speed are
• Kind of work piece material
• Kind of cutting tool material
• Use of cutting fluid
• Size and type of drilling machine
• Quality of finish

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Calculation of cutting rpm

• The required rpm can be obtained from the
  equation
• Metric
• Where,
• CS cutting speed (m/min), from table (1)
• d diameter of twist drill (mm)
• Inch
• Where,
• CS cutting speed (ft/min), from table (1)
• d diameter of twist drill (in)

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Table (1) Cutting Speeds for High Speed Steel
Drills
Table (1) Cutting Speeds for High Speed Steel
Drills
Material Meter/min Foot//min
Low carbon steel 0.05 0.3 carbon ... 24.4 33.5 80 110
Medium carbon steel 0.3 0.6 carbon 21.4 24.4 70 80
High carbon steel 0.6 1.7 carbon . 15.2 18.3 50 60
Steel forgings . 15.2 18.3 50 60
Alloy steel .. 15.2 21.4 50 70
Stainless steel . 9.1 12.2 30 40
Cast iron, soft gray . 30.5 45.7 100 150
Cast iron, hard chilled 21.4 30.5 70 100
Cast iron, malleable 24.4 27.4 80 90
Ordinary brass bronze 61.0 91.4 200 300
High-tensile bronze 21.4 45.7 70 150
Monel metal ... 12.2 15.2 40 50
Aluminium and its alloys ... 61.0 91.4 200 300
Magnesium and its alloys .. 76.2 122.0 250 400
Slate marble stone .. 4.6 7.6 15 25
Bakelite and similar plastics .. 30.5 45.7 100 150
Wood . 91.4 122.0 300 400
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Twist drill materials

• Carbon tool steel
• High speed steel
• Cemented carbide

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Type of twist drills

• General purpose drill
• It suits a wide variety of materials
• Low helix drill
• It is used for soft materials aluminium, brass,
  magnesium etc , for shallow holes
• High helix drill
• It is used for deep holes
• It is used for aluminium, copper, die cast
  materials, plastics
• Core drill
• For drilling punched and cored holes
• Coolant ole drill (oil hole drill)
• It has two holes from the shank to the cutting
  point
• It used in production machines
• Straight flute drills
• for drilling brass, sheet metal work and
  non-ferrous materials

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Safety rules

• Wear safety glasses or goggles
• Never leave the chuck key in a drill chuck at any
  time
• Never leave the drill drift in spindle
• Mount work securely, do not hold thin or small
  work pieces in hands while drilling
• Do not attempt to stop the spindle by the hands
• Keep long sleeves away from spindles
• Long hair could be very dangerous when drilling
• Keep work area and floor clean and free from oil
  and grease

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• Thank You