OSHA 10 Hour Machine Guarding #2
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Trainer Objectives• Explain the general requirements for guarding
the hazards of machines.
• Describe precautions to be taken around woodworking machinery.
• List fundamental requirements for abrasive wheel machinery.
• Identify important terms associated with operation of mechanical presses.
• Describe the requirements for guarding moving parts of machinery.
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
Standard Interpretations 12/20/1994 - Machine-guarding
requirements• You will notice that this standard requires that machine
guards be provided to protect employees from several identified hazards (e.g., points of operation, ingoing nip points), but does not specify the type of machine guard that an employer must use. The standard recommends several types of machine guards, including barriers, tripping devices, and electronic safety devices, but leaves to the employer the decision regarding which machine guard best suits the working conditions.
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.
1910.212(a)(2) General requirements for machine guards
• Guards shall be affixed to the machine where possible and secured elsewhere if for any reason attachment to the machine is not possible
• The guard shall be such that it does not offer an accident hazard in itself
1910.212(a)(3) Point of Operation• (i)Point of operation is the area
on a machine where work is actually performed upon the material being processed
• (ii)The point of operation of machines whose operation exposes an employee to injury, shall be guarded
1910.212(a)(3) Point of Operation• (ii)The guarding device shall be in conformity with
any appropriate standards therefor, or, in the
absence of applicable specific standards, shall be
so designed and constructed as to prevent the
operator from having any part of his body in the
danger zone during the operating cycle
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 operator placing a hand in
the danger zone* *Such tools shall not be in lieu of other guarding
required by this section, but can only be used to
supplement protection provided.
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
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
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.
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
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.
Saws• Used primarily in woodworking and
manufacturing shops• Two types
– Table – Radial arm
• Other types include:
Hand heldBand saw Miter saw
Shears
• Self-contained machines using a mechanically
driven ram
• Ram moves a nonrotary blade at a constant
rate past the edge of fixed blade
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
Power Presses
• NEP covers all types of
power presses
• Presses consist of
stationary bed, and slide
• Used in a variety of
industries
Program Procedures
• NEP includes three
activities:
– Outreach
– Targeting/selection
– Inspection
• If present, a thorough
inspection will be
conducted focusing on:
– Nip points
– Pinch points
– Shear points
– Cutting actions
– Point(s) of operation
1910.213 Woodworking machinery requirements
• (a)(1)Each machine shall be so constructed as
to be free from sensible vibration when the
largest size tool is mounted and run idle at full
speed.
1910.213 Woodworking machinery requirements
• (a)(11)The frames and all exposed, noncurrent-carrying metal parts of portable electric woodworking machinery operated at more than 90 volts to ground shall be grounded and other portable motors driving electric tools which are held in the hand while being operated shall be grounded if they operate at more than 90 volts to ground. The ground shall be provided through use of a separate ground wire and polarized plug and receptacle.
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
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
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
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
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
• 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
1910.213(c)(2) Spreaders
Spreader
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
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
• 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
1910.213(g)(2) Swing cutoff saws
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
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
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
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
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
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
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
• Securely clamped after each adjustment• Adjustments made only when wheel is stopped
Work rest is closelyadjusted
Maximum wheel exposure = 90º
Maximum angle of exposure above the horizontal = 65º
Angular exposure for wheel periphery
Horizontal plane of the spindle
For bench and floor stand grinders
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 inch
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
• 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”
1910.215 (d) Mounting -Ring Test
*A non-metallic implement, wood mallets may be needed for larger wheels
• 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.
1910.215 (d) Mounting
Compare this number to the spindle speed on the grindermotor
Definitions• "Antirepeat" means the part of the clutch/brake
control system designed to limit the press to a
single stroke if the tripping means is held
operated
• "Antirepeat" is also called single stroke reset or
reset circuit
Definitions
• "Brake" means the mechanism used on a
mechanical power press to stop and/or hold the
crankshaft, either directly or through a gear
train, when the clutch is disengaged.
Definitions• "Clutch" means the coupling mechanism used
on a mechanical power press to couple the
flywheel to the crankshaft, either directly or
through a gear train.
• "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.
Definitions• "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.
Definitions
• "Continuous" means uninterrupted multiple
strokes of the slide without intervening stops (or
other clutch control action) at the end of
individual strokes*
*Should generally only be used for auto-feed operations where the operator does not enter the point of operation (Stamping for example)
Definitions• "Device" means a press control or attachment
that:– Restrains the operator from inadvertently reaching
into the point of operation, or
– Prevents normal press operation if the operator's hands are inadvertently within the point of operation, or
Definitions• "Device" means a press control
or attachment that:– Automatically withdraws the
operator's hands if the operator's hands are inadvertently within the point of operation as the dies close, or
– Prevents the initiation of a stroke, or stops of stroke in progress, when there is an intrusion through the sensing field by any part of the operator's body or by any other object
Definitions• "Hand feeding tool" means any hand held tool
designed for placing or removing material or
parts to be processed within or from the point of
operation.
• "Jog" means an intermittent motion imparted to
the slide by momentary operation of the drive
motor, after the clutch is engaged with the
flywheel at rest.
Definitions• "Inch”* means an intermittent motion imparted
to the slide (on machines using part revolution clutches) by momentary operation of the "Inch" operating means
*"Inch" is a function used by the die setter for setup of dies and tooling, but is not intended for use during production operations by the operator
Definitions• "Point of operation" means the area of the
press where material is actually positioned and
work is being performed during any process
such as shearing, punching, forming, or
assembling
Definitions• "Press" means a mechanically powered machine that shears,
punches, forms or assembles metal or other material by means of
cutting, shaping, or combination dies attached to slides.
• A press consists of a stationary bed or anvil, and a slide (or slides)
having a controlled reciprocating motion toward and away from the
bed surface, the slide being guided in a definite path by the frame of
the press.
1910.217(a)(5) Excluded machines
• Press brakes, hydraulic and pneumatic power
presses, bulldozers, hot bending and hot metal
presses, forging presses and hammers, riveting
machines and similar types of fastener
applicators are excluded from the requirements
of this section
1910.217(b)(2) Brakes• Friction brakes provided for stopping or holding
a slide movement shall be inherently self-
engaging by requiring power or force from an
external source to cause disengagement
1910.217(b)(3) Full revolution clutches
• Machines using full revolution clutches shall
incorporate a single-stroke mechanism*
*That means after one complete cycle the press returns to the full open position, and will not re-engage until another cycle is initiated
1910.217(b)(4) Foot pedals (treadle)
• The pedal mechanism shall be
protected to prevent unintended
operation from falling or moving
objects or by accidental stepping
onto the pedal
• A pad with a nonslip contact area
shall be firmly attached to the
pedal Treadle
• Hand controls protected against unintentional operation
• Two-hand trip systems on full revolution clutch machines shall incorporate an antirepeat feature
1910.217(b)(6) Two-hand trip controls
1910.217(b)(7) Part revolution clutches
• The clutch shall release and the brake shall be applied when the external clutch engaging means is removed, deactivated, or de-energized
• The stop control shall override any other control, and re-actuation of the clutch shall require use of the operating (tripping) means which has been selected
• A red color stop control shall be provided with
the clutch/brake control system
• Momentary operation of the stop control shall
immediately deactivate the clutch and apply the
brake
1910.217(b)(7) Part revolution clutches
• A means of selecting Off, "Inch," Single Stroke,
and Continuous (when the continuous function
is furnished) shall be supplied with the
clutch/brake control to select type of operation
of the press
1910.217(b)(7) Part revolution clutches
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;
• It shall, in itself, create no pinch point between
the guard and moving machine parts;
• It shall utilize fasteners not readily removable
by operator, so as to minimize the possibility of
misuse or removal of essential parts;
1910.217(c)(2) Point of operation guards
Table O-10 [In inches]___________________________________________________ | Distance of opening from point | Maximum width of of operation hazard | opening____________________________ |__________________ |
1/2 to 1 1/2 ................. | 1/41 1/2 to 2 1/2 ............... | 3/82 1/2 to 3 1/2 ............... | 1/23 1/2 to 5 1/2 ............... | 5/85 1/2 to 6 1/2 ............... | 3/46 1/2 to 7 1/2 ............... | 7/87 1/2 to 12 1/2 .............. | 1 1/412 1/2 to 15 1/2 ............. | 1 1/215 1/2 to 17 1/2 ..........… | 1 7/817 1/2 to 31 1/2 ............. | 2 1/8
____________________________ |__________________
• 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
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
1910.217(c)(2) Point of operation guards
Presence sensing devices
• The device may not be used on
machines using full revolution clutches!
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.
Pullbackdevice
Adjustablewrist
straps
1910.217(c)(4) Hand feeding tools
• Hand feeding tools are intended for placing and
removing materials in and from the press
• Hand feeding tools are not a point of operation
guard or protection device and shall not be
used in lieu of the "guards" or devices required
in this section
1910.217(d) Setting and feeding dies
• Furnish and enforce the use of hand tools for
freeing and removing stuck work or scrap
pieces from the die, so that no employee need
reach into the point of operation for such
purposes
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
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
• 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
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
1910.219.(c) Shafting
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
Distance between pulleys = 2 inches
Belt width = three inches
Guides must be placedin this area
Example
seven ft. minimumFloor
Unguarded portion
Guard
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
1910.219 (o) Approved Materials
• (1)(i)(a)All guards shall be rigidly braced every three (3) feet or fractional part of their height to some fixed part of machinery or building structure.
• Where guard is exposed to contact with moving equipment additional strength may be necessary.
1910.219(o)(2) Wood guards• Wood guards may be used in the woodworking
and chemical industries, in industries where the
presence of fumes or where manufacturing
conditions would cause the rapid deterioration
of metal guards
• In construction work and outdoors where
extreme cold or heat make metal guards and
railings undesirable
height 42"
Posts not more than 8' apart, permanent, substantial, smooth, w/ no protruding nails, bolts or splinters
Toeboards at least 4" high
midrail half way in-betweenIf wood, 2"x 4" toprail
1910.219(o)(2) Wood guards
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