OSHA 10 hour machine guarding presentation #4

3. A good rule to remember is:
Any machine part, function, or process
which may cause injury must be
safeguarded.
Where the operation of a machine or
accidental contact with it can injure the
operator or others in the vicinity, the
hazards must either be eliminated or
controlled.
If it moves, it merits your attention!

4. Goals
1. Describe the basic hazards involving
machinery including point of
operation and power transmission
devices.
2. Introduce control measures through
effective machine guarding principles
and methods.

5. 1910.212(a)(1) Types of guarding
• One or more methods of machine guarding
shall be provided to protect the operator and
other employees in the machine area from
hazards such as those created by:
– Point of operation,
– Ingoing nip points,
– Rotating parts,
– Flying chips and sparks

6. Point of Operation Hazards
The point where work is actually performed.
Cutting
Shaping
Boring
Forming

12. Part One: The Principles
The purpose of machine guarding is to
protect against and prevent injury from....
Point of operation
Nip points

14. Part One: The Principles
The purpose of machine guarding is to
protect against and prevent injury from....
Point of operation
Nip points
Rotating parts

16. Part One: The Principles
The purpose of machine guarding is to
protect against and prevent injury from....
Point of operation
Nip points
Rotating parts
Flying Chips

17. Part One: The Principles
The purpose of machine guarding is to
protect against and prevent injury from....
Point of operation
Nip points
Rotating parts
Flying Chips
Sparks

18. Where Mechanical Hazards Occur
Three basic areas require safeguarding

19. Where Mechanical Hazards Occur
1. Point of Operation

20. Where Mechanical Hazards Occur
2. Power Transmission Devices
The components
which transmit
energy to the part
of the machine
performing the
work.

21. Where Mechanical Hazards Occur
2. Power Transmission Devices
Flywheels Pulleys
Rods Cams
Couplers Spindles
Chains Sprockets
Gears Shafts

23. Where Mechanical Hazards Occur
3. All Other Moving Parts
All hazardous parts which move while the
machine is working.
Reciprocating
Rotating
Transverse
Feed mechanisms

24. Hazardous Mechanical Motions and
Actions
A wide variety of mechanical motions and
actions may present hazards to the
worker.
• Rotating or reciprocating members
• Moving belts
• Meshing gears
• Cutting teeth
• Any part that impacts or shears

25. Rotating Motion
What are some hazards of rotating
parts?

27. Rotating Motion
In-running nip point hazards
1. Parts rotating in opposite direction

29. Rotating Motion
In-running nip point hazards
2. Rotating and tangentially moving parts

31. Rotating Motion
In-running nip point hazards
3. Rotating and fixed parts

33. Reciprocating Motion
Transverse Motion

34. Standard Interpretations
12/20/1994 - Machine-guarding
requirements
• By not specifying the types of machine guards
that must be used, this standard is referred to
as a "performance" standard (i.e., the employer
is free to adopt a machine guard that
"performs" in such a manner as to meet the
standard's objective--to protect employees from
the identified hazards).
• If OSHA had specified the types of machine
guards that must be used, the standard would
be a "specification" standard.

35. Effective Safeguarding
Must prevent any contact to the
machine hazard and installed to
prevent contact from around, over,
through, or under the guard!
“…so designed and constructed
as to prevent the operator from
having any part of his/her body
in the danger zone during the
operating cycle”
{29 CFR 1910.212(a)(3)(ii)}

36. Effective Safeguarding
• Must be in conformity with any
appropriate standards
• Must not present a hazard in itself
nor create interference

37. Effective Safeguarding
• Must not allow objects to fall into
moving parts
• Allow safe maintenance and
lubrication
• Must be affixed and secured to the
machine where possible

38. Part Two: Safeguarding
There are many ways to safeguard machines!
Determine the appropriate safeguarding method.
Consider
• the type of operation and material
• the size or shape of stock
• the method of handling
• the physical layout of the work area
• production requirements/limitations

39. Part Two: Safeguarding
As a general rule, power transmission apparatus
is best protected by fixed guards that enclose the
danger areas.
Enclosed shaft
end

40. Enclosed chain
& sprocket

41. Part Two: Safeguarding
For hazards at the point of operation, several
types of safeguarding may be considered.
Because safeguarding the point of operation
can provide challenges, one must always
choose the most effective and practical means
available.
Let’s take a look at some strategies

42. Part Two: Safeguarding
1. Guards
Fixed
Interlocked
Adjustable
Self-adjusting

43. Part Two: Safeguarding
2. Devices
Presence Sensing
Pullback
Restraint
Safety Controls
Gates
Rockford Systems, Inc.

44. Part Two: Safeguarding
3. Location/Distance
4. Feeding/Ejection Methods
Automatic/Semi-Auto feed
Automatic/Semi-Auto ejection
Robotics

45. Guard
was
hanging
at the
work
bench!

46. Effective?

47. Effective?

48. First Safeguarding Strategy: Guards
Guards are barriers which prevent access to
danger areas.

49. First Safeguarding Strategy: Guards
Fixed Guards
– A permanent part of the machine
– Not dependent upon moving parts to
perform its intended function
– Constructed of sheet metal, screen, wire
cloth, bars, plastic, or substantial material
– Usually preferable to all other types
because of its simplicity and permanence

52. First Safeguarding Strategy: Guards
Interlocked Guards
When this type of guard is opened/removed
– the tripping mechanism and/or
power automatically shuts off or
disengages
– the machine cannot cycle or be
started until the guard is back in
place

53. First Safeguarding Strategy: Guards
Interlocked Guards
– They may use electrical, mechanical,
hydraulic, or pneumatic power or any
combination of these
– Replacing the guard should not
automatically restart the machine

54. Interlocked Guards

55. Interlocked
guarding
can be
defeated!
This was
taped
down.

56. First Safeguarding Strategy: Guards
Adjustable Guards
– These guards allow flexibility in
accommodating various sizes of stock

59. First Safeguarding Strategy: Guards
Self-Adjusting Guards
The openings of these guards are
determined by the movement of the stock.
– As the operator moves the stock into
the danger area, the guard is pushed
away, providing an opening which is
only large enough to admit the stock
– After the stock is removed, the
guard returns to the rest position

60. Self-Adjusting
Guards

63. Second Safeguarding Strategy: Devices
A safety device may perform one of several
functions.
Rockford Systems, Inc.

64. Second Safeguarding Strategy: Devices
Presence-Sensing Devices
Photoelectric (optical)
– Uses a system of light sources and
controls which can interrupt the
machine's operating cycle

65. Second Safeguarding Strategy: Devices
• It may stop the machine if a hand or
any part of the body is inadvertently
placed in the danger area
Equipment Resale, Inc

67. Second Safeguarding Strategy: Devices
Presence-Sensing Devices
Radiofrequency (capacitance)
– Uses a radio beam that is part of the
machine control circuit
– When the capacitance field is broken,
the machine will stop or will not
activate

69. Second Safeguarding Strategy: Devices
Presence-Sensing Devices
Electromechanical
– Has a probe or contact bar which
descends to a predetermined
distance when the operator initiates
the machine cycle
– If there is an obstruction preventing it
from descending its full
predetermined distance, the control
circuit does not actuate the machine

71. Second Safeguarding Strategy: Devices
• Restrain or withdraw the operator's
hands from the danger area during
operation
Rockford Systems, Inc.

72. Second Safeguarding Strategy: Devices
Pullback
– Pullback devices utilize a series of cables
attached to the operator's hands, wrists,
and/or arms
– This type of device is primarily used on
machines with stroking action
– When the slide/ram is up between cycles,
the operator is allowed access to the point
of operation

74. Second Safeguarding Strategy: Devices
Restraint
– The restraint (holdout) device utilizes
cables or straps that are attached to the
operator's hands at a fixed point
– The cables or straps must be adjusted to
let the operator's hands travel within a
predetermined safe area - there is no
extending or retracting action involved

76. Second Safeguarding Strategy: Devices
• Require the operator to use both
hands on machine controls
Rockford Systems, Inc.

77. Second Safeguarding Strategy: Devices
Two Hand Controls
– Requires constant, concurrent pressure by
the operator to activate the machine
– With this type of device,
the operator’s hands
are required to be at
a safe location (on the
control buttons) and at
a safe distance from
the danger area

78. Second Safeguarding Strategy: Devices
Two Hand Trips
– This device requires
concurrent application
of both the operator’s
control buttons to
activate the machine
cycle, after which the
hands are free.

79. Second Safeguarding Strategy: Devices
Safety Trip Controls
– Provide a quick means for deactivating the
machine in an emergency situation
– A pressure-sensitive bar,
when depressed, will
deactivate the machine

80. Second Safeguarding Strategy: Devices
Safety Trip Controls
– Safety tripwire cables may also be located
around the perimeter or near the danger
area

81. Second Safeguarding Strategy: Devices
• Provide a barrier which is
synchronized with the operating cycle
of the machine in order to prevent
entry to the danger area during the
hazardous part of the cycle
Rockford Systems, Inc.

82. Second Safeguarding Strategy: Devices
Gates
– A gate is a movable
barrier which protects
the operator at the
point of operation
before the machine
cycle can be started
– Usually designed to
operate with each
machine cycle

83. Another Safeguarding Strategy
Guarding by Location/Distance
– The machine or its dangerous moving
parts are positioned so that hazardous
areas are not accessible or do not present
a hazard during normal operation
– walls or other barricades (fences)
– height (above worker)
– size of stock (single end feeding,
punching)

85. Is this adequate distance?

86. Is this adequate
location?

87. Another Safeguarding Strategy
Feeding and Ejection
– Automatic and Semiautomatic Feeding

88. Another Safeguarding Strategy
Feeding and Ejection
– Automatic Ejection

89. Another Safeguarding Strategy
Feeding and Ejection
– Semiautomatic
Ejection

90. Another Safeguarding Strategy
Robotics
– Machines that load and unload stock,
assemble parts, transfer objects, and
perform other tasks
– They perform work otherwise done by the
operator
– Best used in high production processes
requiring repeated routines

91. Robotics

92. Miscellaneous Aids
Does not give complete protection from
machine hazards, but may provide the operator
with an extra margin of safety.
Examples:
•Awareness barriers
•Shields
•Holding tools
•Push sticks or blocks

96. 1910.212(a)(3)(iii) Hand Tools
• Special hand tools for
placing and removing
material shall be such as
to permit easy handling
of material without the
*Such tools shall not be in
lieu of other guarding
operator placing a hand required by this section, but
can only be used to
in the danger zone* supplement protection
provided.

97. 1910.212(a)(3)(iv)
Examples of machines
• Types of machines which normally require point
of operation guarding:
– Mills
– Drills
– Grinders
– Power presses
– Shears
– Saws

98. 1910.212(a)(4) Barrels,
containers, and drums
• Revolving drums, barrels,
and containers shall be
guarded by an enclosure
which is interlocked with
the drive mechanism, so
that the barrel, drum, or
container cannot revolve
unless the guard
enclosure is in place

99. 1910.212(a)(5) Exposure of blades
• When the periphery of the blades of a fan is
less than seven (7) feet above the floor or
working level, the blades shall be guarded
• The guard shall have openings no larger than
one-half (1/2) inch.

100. 1910.212(b) Anchoring fixed
machinery
• Machines designed for a fixed location shall be
securely anchored to prevent walking or
moving
This pedestal grinder is
designed for anchoring,
and is not anchored,
creating a potential
hazard

101. CPL 2-1.35 National Emphasis
Program on Amputations
• Identify and reduce workplace hazards likely to
cause amputations
• top five machines that cause amputations are:
– Saws,
– Shears,
– Slicers,
– Slitters, and
– Presses.

102. Saws
• Used primarily in woodworking and
manufacturing shops
• Two types
– Table
– Radial arm
• Other types include:
Hand held
Band saw Miter saw

103. Shears
• Self-contained machines using a mechanically
driven ram
• Ram moves a nonrotary blade at a constant
rate past the edge of fixed blade

104. Slicers
• Commonly used to
slice meat and food
• Use rotary blade
• Guillotine cutters used
in other industries
• Most injuries occur in
restaurants and
grocery stores

105. Power Presses
• NEP covers all types
of power presses
• Presses consist of
stationary bed, and
slide
• Used in a variety of
industries

106. Program Procedures
• NEP includes three • If present, a thorough
activities: inspection will be
conducted focusing
– Outreach
on:
– Targeting/selection
– Nip points
– Inspection
– Pinch points
– Shear points
– Cutting actions
– Point(s) of operation

124. 1910.213(a)(12) Guarding
blades under tables
• For all circular saws where conditions are such
that there is a possibility of contact with the
portion of the saw either beneath or behind the
table, that portion of the saw shall be:
– Covered with an exhaust hood, or, if no exhaust
system is required,
– With a guard that shall be
arranged as to prevent accidental
contact with the saw

125. 1910.213(b) Machine controls
and equipment
• A mechanical or electrical
power control shall be
provided on each machine
to make it possible for the
operator to cut off the
power from each machine
without leaving his position
at the point of operation

126. 1910.213(b)(3) Non-restart
devices
• On applications where injury to the operator
might result if motors were to restart after
power failures, provision shall be made to
prevent machines from automatically restarting
upon restoration of power

127. 1910.213(b)(4) Location of
controls
• Power controls and
operating controls should
be located within easy
reach of the operator
while he is at his regular
work location, making it
unnecessary for him to
reach over the cutter to
make adjustments

128. 1910.213(c) Ripsaws
• Each circular hand-fed ripsaw shall be guarded
by a hood which shall completely enclose that
portion of the saw above the table and that
portion of the saw above the material being cut

129. 1910.213(c)(2) Spreaders
• Each hand-fed circular ripsaw shall be
furnished with a spreader to prevent material
from squeezing the saw or being thrown back
on the operator
Spreader

130. 1910.213(c)(3) Non-kickback fingers
• Each hand-fed circular
ripsaw shall be provided
with non-kickback
fingers or dogs so
located as to oppose
the thrust or tendency
of the saw to pick up
the material or to throw
it back toward the
operator

131. 1910.213(g)(1) Swing cutoff saws
• Each swing cutoff saw shall be provided with a
hood that will completely enclose the upper half
of the saw, the arbor end, and the point of
operation at all positions of the saw

132. 1910.213(g)(2) Swing cutoff
saws
• Each swing cutoff saw shall be provided with an
effective device to return the saw automatically
to the back of the table when released at any
point of its travel

133. 1910.213(h) Radial saws
• The upper hood completely encloses the upper portion
of the blade down to a point that will include the end of
the saw arbor
• Radial saws used for ripping provided with
nonkickback fingers or dogs located on both sides of
the saw so as to oppose the thrust or tendency of the
saw to pick up the material or to throw it back toward
the operator

134. 1910.213(i) Bandsaws
• All portions of the saw blade shall be enclosed
or guarded, except for the working portion of the
blade between the bottom of the guide rolls and
the table

135. 1910.213(i) Bandsaws
• Bandsaw wheels shall be
fully encased
• The outside periphery of
the enclosure shall be
solid
• The front and back of the
band wheels shall be
either enclosed by solid
material or by wire mesh
or perforated metal

136. Treadle
• Each operating treadle shall be covered by an
inverted U-shaped metal guard, fastened to the
floor, and of adequate size to prevent
accidental tripping

138. 1910.215(a)(2) Guard design
• The safety guard
shall cover the
spindle end, nut,
and flange
projections
• The safety guard
shall be mounted
so as to maintain
proper alignment
with the wheel

139. 1910.215(a)(2) Guard design
• The strength of the fastenings shall exceed the
strength of the guard, except:
– Where the work provides suitable protection, the
guard may expose the spindle end, nut and flange
– Where the work entirely covers the side of the
wheel the side cover(s) of the guard may be omitted

140. 1910.215(a)(4) Work Rests
• On off hand grinding, work rests are required,
to support the work
• Rigid construction, and adjustable with wheel
wear
• Must be kept closely adjusted, max gap = 1/8"
to prevent work from jamming & breaking wheel
Work rest is closely
adjusted
• Securely clamped after each adjustment
•

141. 1910.215(b)(9) Exposure
adjustment
• Safety guards of the type where the
operator stands in front of the
opening, shall be so constructed so
that the peripheral protecting
member can be adjusted to the
constantly decreasing size of the
wheel
• The distance between the periphery
and the adjustable tongue guard
shall never exceed one-fourth

142. 1910.215 (d) Mounting
• Inspection:
– Immediately before mounting, all wheels shall be
closely inspected and sounded by the user (ring
test) to make sure they have not been damaged in
transit, storage, or otherwise
– The spindle speed of the machine shall be checked
before mounting of the wheel to be certain that it
does not exceed the maximum operating speed
marked on the wheel

143. 1910.215 (d) Mounting -Ring Test
• Sound the wheel by
tapping around the
wheel periphery with
a wood handled
screwdriver*
• Good wheel portions
will “ring” like a bell
• Cracks will sound
“dead”
*A non-metallic implement,
wood mallets may be
needed for larger wheels

144. 1910.215 (d) Mounting
• The spindle speed of
the machine shall be
checked before
mounting of the
wheel to be certain
that it does not
exceed the
maximum operating
speed marked on
Compare this number to the
the wheel. spindle speed on the grinder
motor

149. Definitions
• "Full revolution clutch" means a type of clutch
that, when tripped, cannot be disengaged until
the crankshaft has completed a full revolution
and the press slide a full stroke.
• "Part revolution clutch" means a type of clutch
that can be disengaged at any point before the
crankshaft has completed a full revolution and
the press slide a full stroke.

150. 1910.217(c)(2) Point of
operation guards
• It shall prevent entry of hands or fingers into the
point of operation by reaching through, over,
under or around the guard;
• It shall conform to the maximum permissible
openings of Table O-10;

151. Table O-10
[In inches]
___________________________________________________
|
Distance of opening from point | Maximum width of
of operation hazard | opening
____________________________ |__________________
|
1/2 to 1 1/2 ................. | 1/4
1 1/2 to 2 1/2 ............... | 3/8
2 1/2 to 3 1/2 ............... | 1/2
3 1/2 to 5 1/2 ............... | 5/8
5 1/2 to 6 1/2 ............... | 3/4
6 1/2 to 7 1/2 ............... | 7/8
7 1/2 to 12 1/2 .............. | 1 1/4
12 1/2 to 15 1/2 ............. | 1 1/2
15 1/2 to 17 1/2 ..........… | 1 7/8
17 1/2 to 31 1/2 ............. | 2 1/8
____________________________ |__________________

152. 1910.217(c)(2) Point of
operation guards
• Preventing and/or
stopping normal
stroking of the press
if the operator's
hands are
inadvertently placed
in the point of
operation;
Presence sensing device

153. 1910.217(c)(2) Point of
operation guards
• Requiring application of both
of the operator's hands to
machine operating controls
and locating such controls at
such a safety distance from
the point of operation that the
slide completes the downward
travel or stops before the
operator can reach into the
point of operation with his
hands; or

154. Presence sensing devices
• The device may not be used on
machines using full revolution clutches!

155. 1910.217(c)(3)(iv)(d) Pull-out
device
• Each pull-out device in use shall be visually
inspected and checked for proper adjustment at
the start of each operator shift, following a new
die set-up, and when operators are changed.
• Necessary maintenance or repair or both shall
be performed and completed before the press
is operated.
• Records of inspections and maintenance shall
be kept in accordance with paragraph (e) of this
section.

156. Pullback
device
Adjustable
wrist
straps

158. 1910.219(b)(1) Flywheels
• Flywheels 7 feet or less
above the ground shall be
guarded
• Sheet, perforated, or
expanded metal or woven
wire, or with
• Guard rails between 15 to 20
inches from flywheel rim
• Toe board if within 12 inches
of floor or extends into a pit
• All projections shall be
covered

159. 1910.219.(c) Shafting
• Each continuous line of shafting shall be
secured in position against excessive end
movement
• Inclined and vertical shafts* shall be securely
held in position against endwise thrust
*Particularly inclined idler shafts

160. 1910.219.(c) Shafting
• All exposed parts of horizontal shafting 7 ft. or
less above the floor shall be guarded (except:
runways used for oiling or running adjustments)
by a stationary casing, or by a trough
• Troughs must enclose sides and top, or sides
and bottom of shafting as location requires

161. 1910.219.(c) Shafting
Projecting end shafts
shall present a smooth
edge and project not more
than 1/2 the diameter of
the shaft
Unused key ways shall be
filled up or covered

162. 1910.219(d) Pulleys
• Pulleys, any parts of which are seven feet or
less from the floor or working platform, shall be
guarded in accordance with the standards
specified in paragraphs (m) & (o)
• Pulleys serving as balance wheels (e.g., punch
presses) on which the point of contact between
belt and pulley is more than six feet six inches
from the floor or platform may be guarded with
a disc covering the spokes

163. Example
Belt width = three inches
Distance between
pulleys = 2 inches
Guides must be placed
in this area

164. Guard
Unguarded portion
seven ft. minimum
Floor

165. 1910.219 (f) Gears sprockets
and chains
• Gears, sprockets and
chains shall be guarded by
one of the following
methods:
• By a complete enclosure; or
• By a standard guard as in
paragraph (o), at least
seven feet high, extending
six inches above the mesh
point of the gears; or