3. General safety in workshop
“Safety first”
“An unsafe worker is an unwanted worker”
• Follow instructions: The safe way to do a job is to
do it in the correct way.
• Use the right tools for right works.
• Never use any power tools without permission from
responsible person.
Causes of Accidents
• Faulty attitude toward safety.
• Failure to recognize a danger.
• Emotions: such as worry, fear, anger, uncertainty or
excitement.
4. General safety measures
• Dress correctly!
• Remove rings, wrist watches, necklaces and
bracelets!
• Always walk in the shop!
• Protect your eyes!
• No scrap materials on floor!
It is better to be safe than sorry!
• Small cuts, burns, scratches are common in the
workshop.
5. • Use wire brush to remove metal chips or burrs;
don’t use your bare hands.
• When working with power hand tools or machineries,
protect the cable from sharp edges or falling down
items.
Wire brush
6. Personal safety equipment
• Safety goggles;
• Safety shoes;
• Working jacket (with long sleeves);
• Ear plug, Safety gloves and Safety helmet.
Personal protective equipment
7.
8. Measuring tools and equipment
• Tape rule
• A measuring tape is a flexible form of ruler.
• It consists of a ribbon of cloth, plastic, or metal strip
with linear measurement markings.
• Its flexibility allows for a measure of great length to be
easily carried in pocket or toolkit and permits one to
measure around curves or corners.
9. • Steel rule
• Vernier Caliper
• A Vernier caliper is precision measuring tool.
• We can measure inside, outside and depth of holes.
• It has locknut to keep the measurement permanently.
12. • Micrometer
• A tool for taking outside, inside, and height
measurements.
• More precise measuring instrument than vernier
calipers.
13. Types of Micrometer
• Outside micrometer: to measure the thickness or
outside diameter of parts.
• Inside micrometer: Used to measure the inside diameter
of holes.
• Depth micrometer: Measures depths of holes, slots and
steps.
15. Marking and Hand Tools
• Surface plate/table
• Used for testing the flatness
and trueness of surfaces.
• It is made up of cast iron or
graphite.
• Its upper face is planed to
form a very smooth surface.
• It is also used in scribing
work.
• While not in use, it
should be covered.
16. • Scriber
• Used for mark lines on work pieces, prior to machining.
• Punches
• Used for marking purposes.
• Dot punches are used for marking dotted line and
center punch is used to mark the center of a hole before
drilling.
17.
18. E. Punch holder
F. Center punch
G. Pin punch
H. Long tapered punch
I. Starting punch
• Punches come in several configurations.
• A center punch is frequently used to start a hold
before drilling.
Punch designs
20. • Vernier Height gauge
• A height gauge is a
measuring device used
either for determining
the height of something,
or for repetitious
marking of items to be
worked on.
21. • HackSaw
• Used for cutting of rods, bars, pipes, flats etc.
• The blade teeth
should point away
from the handle,
and the blade
should be fastened
tightly in the frame.
22. • Files
• Files are multi points
cutting tools.
• It is used to remove
the material by
rubbing it on the
metals.
• Files are available in
a number of sizes,
shapes and degree of
coarseness.
23. Chisels
• In chiseling the cutting edge of a chisel is driven into
a workpiece by impact.
• A chisel must be harder than the piece being worked.
• There are various chisel shapes.
A. Flat Chisel
B. Cape Chisel
C. Round-nose cape chisel
D. Diamond-point chisel
E. Chisel holder
25. Holding Tools
• A Vise is used to hold parts during cutting, drilling,
hammering, and pressing operations.
• It is mounted on a workbench.
26.
27. Thread Cutting with tap and Dies
• A thread is a spiral or helical groove cut on the inside or
outside of a cylinder or cone.
• Threads are used to hold parts together, transmit power
and provide accurate measurements.
28. Parts of a Thread
Basic parts of a thread
• Major diameter: the outer or
largest diameter.
• Minor diameter: the
smallest diameter.
• Pitch: the distance between
adjoining threads.
29. Taps and dies
• A tap is used for cutting threads inside of a hole.
• A tap is made from high carbon steel or high speed
steel and is very hard.
• The upper part of tap consists of a shank ending in a
square for holding by tap wrench.
• lower part has threads cut and three to four flutes cut
across the thread.
• The lower part is some what tapered so that it can be
inserted in to smaller hole than the threads to be cut.
• oil can be used to ensure smooth cutting.
31. Tap holder and die stock
• Tap holder or tap wrench is used to hold taps during
internal thread.
• Die stock is used to hold dies during cutting of
external threads.
32. Cutting internal and external threads
Internal thread
• First, measure the thread on the screw or bolt you
intend to use.
• Second, determine the correct size hole to drill before
tapping.
• After the hole has been drilled, clamp the work in a
vise with the hole in an upright position.
33. • Apply a good grade of cutting oil to the tap.
• Grasp the tap wrench with your right hand directly
over the tap, or with both hands close to the tap, and
place the tap in the hole.
• Press and start to turn the tap clockwise into the hole.
• Turn the tap forward until resistance is felt and then
turn the tap a quarter-turn backwards to break the
chip.
34. • Grasp the wrench by both handles and with a slow,
steady movement, continue turning the tap into the
hole, backing up occasionally (when increased
resistance is felt) to allow the chips to break.
• Never force a tap because it can become so tightly
wedged that it will break.
35. External threads
• Dies are used to cut external threads on the outside of
pipes, rods or bolts.
• The die is held in a Die Stock and worked in much the
same manner as a tap.
What are Dies?
• Dies are made either of high-carbon steel or of high-
speed steel. Unlike taps, dies are used for cutting
external (male) threads.
36. Procedures for cutting external threads
1. Square the end of the work and chamfer it (using a file,
grinding machine or centre lathe) for an easy start .
2. Grip the die, held in the stock, firmly and squarely on
the work.
3. Turn clockwise, about a quarter-turn, and ease back to
remove chippings.
4. Apply a good supply of oil (lubricant).
5. Make adjustments of the screws after making a full cut
until the depth required is achieved.
39. Fundamentals of Welding
Welding
• A joining process of two materials that
coalesced at their contacting (faying) surfaces by the
application of pressure and/or heat.
• Sometime a filler material to facilitate coalescence.
Advantage: portable, permanent, stronger than the
parent materials with a filler metal, the
most economical method to join in terms of
material usage and fabrication costs .
Disadvantage: Expensive manual labor, high
energy and dangerous, does not allow
disassemble and defects.
40. Applications
• Constructions, Piping, pressure vessels.
• Boilers and storage tanks, Shipbuilding, Aerospace.
• Automobile and Railroad.
• Automation - Machine, Automatic and Robotic
welding.
Arc welding (AW): is a fusion-welding process in
which coalescence of the metals is achieved by the heat
of an electric arc between an electrode and the work.
41. Two Basic Types of Arc Welding (Based on
Electrodes)
1. Consumable electrodes
consumed during welding process
added to weld joint as filler metal
in the form of rods or spools of wire
2. Non-consumable electrodes
not consumed during welding process but does get
gradually eroded
filler metal must be added separately
42. Cont...
• If the electrode is intended to be permanent, the
processes are called permanent electrode arc welding
processes or, more commonly, non consumable
electrode arc welding processes.
• If the electrode is intended to be consumed, the
processes are called consumable electrode arc
welding processes.
43. Consumable Electrode AW Processes
Shielded Metal Arc Welding (or Stick Welding)- SMAW
Gas Metal Arc Welding (or Metal Inert Gas Welding)-
GMAW
Submerged Arc Welding - SAW
Flux-Cored Arc Welding - FCAW
Electro-gas Welding
44. Uses a consumable electrode consisting of a filler
metal rod and coating around rod.
Coating composed of chemicals that provide flux and
shielding.
Low cost welding system: Power supply, connecting
cables, and electrode holder available for.
Shielded Metal Arc Welding (SMAW)
53. GMAW Advantages over SMAW
1. Continuous welding because of continuous wire
electrode. Sticks must be periodically changed in
SMAW.
2. Higher deposition rates.
3. Eliminates problem of slag removal.
4. Can be readily automated.
5. Has better control to make cleaner & narrower welds
than SMAW.
54. GMAW Applications
1. Used to weld ferrous and various non-ferrous metals.
2. Good for fabrications such as frames and farm
equipment.
3. Can weld thicker metal (not as thick as SMAW).
55.
56.
57.
58.
59.
60. Parameters for effective welding
Successful welding depends on the following factors:
• Selection of the correct electrode
• Selection of the correct size of the electrode for the
job
• Correct welding current
• Correct arc length
• Correct angle of electrode to work
• Correct travel speed
• Correct preparation of work to be welded.
61. Types of Weld Joint and Welds
Types of Joints
– Butt joint
– Corner joint
– Lap joint
– Tee joint
– Edge joint
Types of Welds
– Fillet weld
– Groove weld
– Plug and slot
welds
– Spot and Seam
welds
– Flange and
Surfacing welds
62. Five basic types of Joints:
(a) Butt, (b) Corner,
(c) Lap, (d) Tee and
(e) Edge
65. Butt welds : A butt weld is made between two pieces of
metal usually in the same plane, the weld metal
maintaining continuity between the sections.
66. Fillet welds
These welds are roughly
triangular in cross
section and between two
surfaces not in the same
plane and the weld metal
is substantially placed
alongside the
components being
joined.
70. Brazing and Soldering
• Brazing and soldering both use filler metals to join two
(or more) metal parts to provide a permanent joint.
• It is difficult, although not impossible, to disassemble
the parts after a brazed or soldered.
• Brazing and soldering lie between fusion welding and
solid-state welding.
• A filler metal is added in brazing and soldering as in
most fusion-welding operations; however, no melting
of the base metals occurs, which is similar to solid-state
welding.
71. • Brazing and soldering are attractive compared to
welding under circumstances where
1. the metals have poor weldability,
2. dissimilar metals are to be joined,
3. the intense heat of welding may damage the
components being joined,
4. the geometry of the joint does not lend itself to any
of the welding methods, and/or
5. high strength is not a requirement.
72. • Brazing is a joining process in which a filler metal is
melted and distributed by capillary action between the
faying surfaces of the metal parts being joined.
• No melting of the base metals occurs in brazing; only
the filler melts.
• In brazing the filler metal (also called the brazing
metal), has a melting temperature (liquidus) that is
above 4500C (8400F) but below the melting point
(solidus) of the base metals.
73. • Disadvantages and limitations of brazing include
(1) joint strength is generally less than that of a welded
joint;
(2) although strength of a good brazed joint is greater
than that of the filler metal, it is likely to be less than
that of the base metals;
(3) high service temperatures may weaken a brazed
joint; and
(4) the color of the metal in the brazed joint may not
match the color of the base metal parts, a possible
aesthetic disadvantage.
74. • Brazing as a production process is widely used in a
variety of industries, including
• automotive (e.g., joining tubes and pipes),
• electrical equipment (e.g., joining wires and
cables),
• cutting tools (e.g., brazing cemented carbide
inserts to shanks),
• jewelry making.
75. Brazed joints
(a) Conventional butt joint,
and adaptations of the butt
joint for brazing:
(b) scarf joint,
(c) Stepped butt joint,
(d) Increased cross section
of the part at the joint..
(a) Conventional lap
joint, and adaptations
of the lap joint for
brazing:
(b) cylindrical parts,
(c) sandwiched parts, and
(d) use of sleeve to
convert butt joint into
lap joint.
76. • Soldering is similar to brazing and can be defined as a
joining process in which a filler metal with melting
point (liquidus) not exceeding 4500C (8400F) is melted
and distributed by capillary action between the faying
surfaces of the metal parts being joined.
• As in brazing, no melting of the base metals occurs, but
the filler metal wets and combines with the base metal
to form a metallurgical bond.
• Surfaces to be soldered must be precleaned so they are
free of oxides, oils, and so on.
• An appropriate flux must be applied to the faying
surfaces, and the surfaces are heated.
• Filler metal, called solder, is added to the joint, which
distributes itself between the closely fitting parts.
77. • Soldering is most closely associated with electronics
assembly .
• It is also used for mechanical joints, but not for joints
subjected to elevated stresses or temperatures.
Advantages attributed to soldering
(1) Low energy input relative to brazing and fusion welding,
(2) Variety of heating methods available,
(3) Good electrical and thermal conductivity in the joint,
(4) Easy to repair and rework.
Disadvantages of soldering
(1) Low joint strength unless reinforced by mechanically means
(2) Possible weakening or melting of the joint in elevated
temperature service.
78.
79. • Most solders are alloys of tin and lead and their
alloys, since both metals have low melting points.
80.
81. Drilling
• Most twist drills used in machine shop work today
are made of high-speed steel.
• High-speed drills have replaced carbon-steel drills
since they can be operated at double the cutting speed
and the cutting edge lasts longer. A drill may be
divided into three main parts: the shank, the body and
the point.
82. • drills up to 13mm in diameter have straight drill
shanks.
• those over this diameter usually have tapered shanks.
• Streight-shank drills are held in a drill chuck;
tapered-shank drills fit into the internal taper of the
drill press spindle.
83. • The flutes are two or more helical grooves cut
around the body of the drill.
• They form the cutting edges, admit cutting
fluid, and allow the chips to escape.
84. Speed
• A wide range of drills and drill sizes is used to cut
various metals; an equally wide range of speeds is
required for the drill to cut efficiently.
• It is essential to select the correct cutting speed
and the feed. Followings are the most common
used cutting speed and feed rate.
86. The most economical drilling speed depends upon many
variables such as:
• The type and hardness of the material
• The diameter and material of the drill
• The type and condition of the drill press
• The efficiency of the cutting fluid employed
To determine the correct number of rpm (revolution per
minute) of a drill press spindle for a given size drill, the
following should be known:
• The type of material to be drilled
• The recommended cutting speed of the material
• The type of material from which the drill is made
87. Feed
• Feed is the distance that a drill advances into the work
for each revolution.
• Drill feeds may be expressed in decimals, fractions of
millimeters.
• Since the feed rate is a determining factor in the rate of
production and the life of the drill, it should be carefully
chosen for each job. The rate of feed is generally
governed by:the diameter of the drill
–the material of the work piece
–the condition of the machine
88.
89.
90. All of the operations use rotating tools.
(a) Reaming to slightly enlarge a hole, to provide a better
tolerance on its diameter, and to improve its surface finish.
(b) Tapping to provide internal screw threads on an
existing hole.
(c) Counter boring provides a stepped hole, in which a
larger diameter follows a smaller diameter partially into the
hole.
(d) Counter sinking similar to counter boring, except that
the step in the hole is cone-shaped for flat head screws and
bolts.
(e) Centering to drill a starting hole to accurately establish
its location for subsequent drilling.
(f) Spot facing to provide a flat machined surface on the
work part in a localized area.
91.
92. Drill presses
• The standard machine tool for drilling is the drill press.
• There are various types of drill press, the most basic of
which is the upright drill.
• The upright drill stands on the floor and consists of a
table for holding the work part, a drilling head with
powered spindle for the drill bit, and a base and column
for support.
• A similar drill press, but smaller, is the bench drill,
which is mounted on a table or bench rather
than the floor.
93.
94. Lathe machine and operations
• Lathe is one of the most versatile and widely used
machine tools.
• It is commonly known as the mother of all other
machine tool.
• The main function of a lathe is to remove metal from
a job to give it the required shape and size.
98. Lathe machine operations
Machining operations other than turning that are performed on a lathe: (a)
facing, (b) taper turning,(c) contour turning, (d) form turning, (e) chamfering,
(f) cutoff, (g) threading, (h) boring, (i) drilling, and (j) knurling.
