Yangon Technological University
Department of Mechanical Engineering
Workshop Technology II
WS-22012
Daw Ei Ei Soe
Lecturer
09757866071
eieisoe.me@gmail.com
Chapter (2)
Safety in the Machine Shop
General Shop Safety
1. Why is it dangerous for a machine
operator to wear a woolen
sweater?
 The strands of the wool that go into
the making of a sweater are long and
unbroken.
 One strand caught on a revolving dog
or job can bring the machine operator
much closer to danger.
 Machine tool spindles, whether on a
lathe or a drill press, turn many
revolutions in a second, and much
damage can be done2 before the
machine is brought to a stop.
2. What is the objection to wearing canvas shoe in a
machine shop?
 The soft material from which the
upper part of the canvas shoe is made
offers no resistance to a hard object,
whether it is falling or stumbled
against.
 The
rubber
soles
are
easily
penetrable by steel chips and sharpedged machined surfaces.
 Strongly made safety shoes having
steel toe caps offer good insurance
against injuries.
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Continued
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3. When should gloves be
worn in a machine shop?
 Gloves should be worn when
the worker is moving sheet
metal or large pieces of
stock, especially when stock
edges are sharp or ragged.
 Gloves should also be worn
when the worker is pouring
liquids that are injurious to
human skin and whenever it
is necessary for him to
handle metal chips of any
size or shape.
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4. Why should goggles or safety
glasses be worn by everybody
working in the machine shop?
 Injury to the eye can be caused
by flying particles of metal that
result when the work piece resists
the cutting tool.
 These flying pieces of metal do
not single out the man behind the
cutting tool.
 Chips can fly in any direction to
hit anybody in the shop.
Everybody in the shop needs the
protection of safety glasses.
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5. How should long steel bar stock be carried
in the shop?
 Although it is often easier to carry long
pieces of stock on the shoulder, it is not a
safe way.
 We tend to watch where we are going and
forget what happens to the part we are not
watching.
 Stock should be carried vertically so that
all of it can be watched at the same time.
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Continued
Fig. 2.10, The UNSAFE way to carry stock
Fig. 2.11, The SAFE way to carry stock
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6. Why is it dangerous to leave
pieces of stock on the floor of the
shop?
 Men do not walk through a machine
shop with their eyes looking at the
floor, therefore a workman is apt to
step on a small piece of stock left on
the floor.
 A fall can cause serious injury. A fall
that carries the victim into a moving
machine can be fatal.
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7. When does grease become a hazard to
safety?
 When it drips or is dropped on the
shop floor.
 An oil stick under a quick-moving
foot may result in a serious
accident.
 Wipe up grease and oil that is
dropped on the floor.
 Clean off the excess grease that
is left near bearings and grease
cups.
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8. How should chips be
removed from the table or
bed of a machine?
 Because metal chips have
sharp edges, which cut
and penetrate skin, chips
should never be handled.
 Machine can be kept clear
of chips by periodically
sweeping (or brushing)
them away.
Cleaning
brush
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Sweeping
brush
Safety on the Bench
9. What causes the greatest number of accidents
to bench workers?
 Most accidents to bench
workers are caused by
thoughtless use of tools,
which includes using a
tool incorrectly or
carelessly.
 Many accidents result
from using a tool to do
something for which it
was not intended.
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10. Many painful accidents are caused by
pointed or sharp-edged tools. What can
be done to avoid this type of accident?
 Sharp-edged or pointed tools
should not be carried in
clothing pockets.
 Arrange the tools on the
bench with the sharp ends
toward the back of the
bench.
 Lay the tools on a cloth to
protect edges.
 Pick them up carefully.
 Use the right tool for the job.
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11. What are the rules for the safe use of files?
A. Be sure that the
file has a handle. See
that the handle fits
security. Never use a
file without a handle.
B. Remove burrs and abrasions
from the file handle before
using it. They cause blisters.
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C. Do not use a file as a
hammer. Flying pieces of
hardened steel can pierce
human skin.
D. Striking a file with a
hammer will also cause
steel splinters to fly.
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E. Using a file as a pry
bar is a sure way of
breaking it.
F. Keep files separated
from each other and do
not throw files against
other files when returning
them to the tool drawer.
G. Keep file teeth clear of
pins. Do not let oil and
dirt collect in the gullets
of the file. A file that slips
over the metal can cause
skinned knuckles.
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12. Many workers are hurt because of the
misuse of hammers. What rules, if followed,
will remove the cause of these accidents?
A. Always check the fit of the handle in the hammer
head. Make sure that the wedge is in place, and
tight.
B. Do not use a hammer with a broken or split
handle.
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C. Always remove oil, grease, and dirt from
the face and the handle of the hammer.
D. Never use the face of the hammer to
strike against another hardened tool.
E. Use the right sized hammer for the job an
8-0z hammer will not do the work of a 1
½ - lb hammer.
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Hacksaw Safety
13. Why is it unsafe to use a dull hacksaw blade?
 If a saw does not cut efficiently, it seems practical to
apply more pressure.
 However, this is wrong. More pressure, with poor
cutting action, will cause the blade to break.
14. How should the hacksaw blade be mounted in
the saw frame?
 The teeth of the hacksaw blade should be pointed
away from the handle and toward the front of the
frame.
 Tension should be sufficient to prevent the blade from
bending, and the blade should be straight, not
twisted.
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15. What other rules should be observed for the
practice of safety when hacksawing?
A. Grip the work in the vise so that the saw cut will
be near the jaws.
B. Apply pressure only on the forward stroke.
C. Start the saw cut with a light, even, forward stroke,
holding the saw frame at an angle. When the cut is
established, hold the frame level and saw the full
width of the job.
D. Take the longest stroke possible, but do not permit
the blade-supporting pins to touch the job.
E. Use a blade having the proper number of teeth per
inch to suit the job fine pitch for thin metal coarse
pitch for thick pieces.
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How To Use a Hacksaw
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Drill Press Safety
Drill Press
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16. What is the most common cause of
accidents on a drill press?
 Most drilling accidents are caused by
the work not being securely fastened.
 The job must be securely held clamped,
or bolted down, whatever size hole is
being drilled.
17. Why is it dangerous to drill work held by hand?
When the fast-moving drill bites into the work, it transfers
some of its rotating force to the workpiece.
Hands cannot maintain a secure enough hold to prevent the
rotating force from whirling the work away from the operator.
The force may be strong enough to send the flying
workpiece toward a distant area of the shop, causing injury
to an unsuspecting co-worker.
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18. When work to be drilled is held in a vise should the
vise be bolted to the table?
 Whenever possible the vise should be bolted to the
table to prevent the rotary force of the drill from
dislodging the work and causing personal injury, ruined
work , a broken drill, or a combination of the three.
 Never try to hold the work by hand.
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19. Why should the drill
press operator keep his
hair cut short, or wear a
cap?
To prevent stray strands of
hair from being caught in the
fast-moving belts or the
revolving drill spindle.
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20. How can a dull drill
cause an accident?
 A dull drill will not cut,
but the inexperienced
operator will increase the
pressure of the feed,
hoping to force the drill
into the work.
 The drill will break, and
the flying pieces cause
painful injuries.
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21. What are the most important rules for
safe operation of the drill press?
Follow these safe drilling practices:
A. Think about what you are doing. Keep
your mind on the job.
B. Dress safety. Remove rings, watches,
identification bracelets, and neckties.
Roll up sleeves.
C. Fasten the job or vise securely to the
table.
D. Remove tools, clamps wrenches, and so
forth from the table before starting the
drill.
E. Remove drill drift from spindle or chuck
key from the drill chuck immediately after
use.
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F. When the drill becomes dull, resharpen it
or replace it.
G. Grind the drill correctly for the metal it is
required to cut.
H. As the drill breaks through the work
relieve the down-feed pressure.
I. Stop the machine before measuring or
adjusting the job.
J. Stop the machine before using a brush to
remove chips and excess coolant.
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Safety on the Lathe
Lathe Machine Operation
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22. How should the chips from the lathe be
prevented from winding around the job?
 A short piece of wood may be used to push the
winding chip down into the lathe pan.
 The chip will break and remain in the pan.
 Accumulated chips should be swept up into a
disposal can.
 Chips should never be touched by hand.
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23. Why is it considered
dangerous to permit a
large accumulation of
chips in the lathe pan?
 A long chip may begin to
wind around the revolving
job.
 Such a chip will carry the
chips from the lathe pan
with if.
 Even if the winding chips
do
not
injure
the
machinist
who
is
operating the lathe, they
can spoil the job.
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24. How can wearing jewelry
create safety hazards for
the lathe operator?
 Loose-fitting jewelry, such
as an identification bracelet,
or an article raised above
the skin surface, such as a
ring, can easily be caught
on a revolving machine part
which would drag a hand or
arm into the moving
machinery, causing serious
injury.
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Operation of Milling Machine
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Milling Safety
25. How should milling
cutters be handled?
 Milling
cutters
have
sharp cutting edges and
should
be
handled
carefully.
 They should be held-in a
piece of cloth to prevent
injury to the operator
and to the cutting edges.
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26. Why do careful milling machine
operators place their tools on a board or
piece of cloth?
 Milling cutters have sharp edges that
should not be chipped or dulled.
 Placing these tools on a wooden board
protects both the cutting edges of the
cutters and the surface of the milling
machine table.
 It also helps the operator to keep his tools
together and prevents them from sliding
around when the machine vibrates.
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27. Is there a safe side and an unsafe side of a milling
machine when the cutter is revolving?
 The milling machine operator should not stand on the side that
the cutter is entering the work.
 The revolving cutter can drag the brush or anything else that
gets near enough into the work.
 The operator should always stand on the going away side of
the cutter.
28. Why do milling machine safety rules emphasize the
importance of keeping away from the cutter?
 There is a tendency for the new operator to get too close to the
place where the cutter is removing metal.
 This makes it possible for the flying chips to cut the operator’s
face.
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 Also, fumes and spray from the soluble coolant oils may cause
Shaper Operation
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Shaper Safety
29. What part of the shaper operator’s body is most
frequently injured?
 Most accidents happen to the operator’s hands.
 Fingers are caught between the cutting tool and the work.
 It is dangerous to attempt to remove chips by hand.
 Wait until the cutting tool is on the return stroke; then
brush the chips away.
30. Why should the operator of the shaping machine wear
safety glasses?
▪ The chips released by the shaper cutting tool seem to fly with
extra force.
▪ That is why not only the shaper operator, but all those near the
shaper should protect their eyes with safety glasses.
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31. Why should the speed and length of the
stroke be checked before starting the
machine?
 If the longest stroke is operated at the
highest speed the mechanism of the machine
can become damaged.
 Always check speed and stroke before
engaging the clutch.
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Safety on the Grinding Machine
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32. What are the principal safety rules that the grinding
machine operator must follow?
Follow these safe grinding practices:
A. Safety goggles must be worn at all times.
B. Test the soundness of the grinding wheel and inspect it
for cracks before mounting it on the machine spindle.
C. Check the wheel bushing and the machine spindle for
size identification. The bushing must neither extend
beyond the width of the wheel nor bind tightly on the
spindle.
D. Wheel blotters must be fitting between the wheel and the
flanges. The blotters must be the same diameter as the
flanges, never less.
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E. Check the operating speed of the machine and
compare it with the wheel manufacturer’s
recommendations.
F.
See that all guards and protective hoods are in
place and tightly secured before starting the
machine. Turn wheel over by hand to check
clearance.
G. Check to make sure that the wheel is clear of the
work and that the feed is disengaged before
starting the machine.
H. Make certain that small work is securely nested and
the nest is blocked on two sides.
I. Do not start an unguarded machine. Using
unguarded machines can lead to eye injuries or
other serious
injuries.
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J. Before starting any grinding wheel stand to one
side, allow the wheel to run full speed for one full
minute to insure that it is sound.
K. Always feed the work gently and steadily into the
revolving grinding wheel.
L. Keep your head out of the line of the sparks.
M. Never place your hands near the revolving wheel.
N. Never attempt to remove work, open vise, or shut
off magnetic chuck until the wheel clears the job
and has come to a complete stop.
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THANK YOU
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