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Subpart O - Machine Guarding

OTI 501 Paul Schlumper

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We Will Cover:

Machine Guarding PrinciplesSubpart O - HighlightsMock Plant Walk-Through

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Why are machines not guarded?

No one would stick their arm, hand, finger, head, etc. in there.

No one is supposed to be back there, in there, around it while it is running.

The machine came that way; it never had a guard.

I’ve been doing it this way for twenty years without any problems.

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Why are machines not guarded? (cont.)

The guard is in the wayThe OSHA inspector didn’t say anything

about it.We’ll put it back on if OSHA comes.

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Emphasis on Amputations : Where does it apply?

General industry employers whose workplaces include:shearssawsslicersslitterspower presses

(the 4s and a P)

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Requirements for Safeguards

Prevent contact - prevent worker’s body or clothing from contacting hazardous moving parts

Secure - firmly secured to machine and not easily removed Protect from falling objects - ensure that no objects can

fall into moving parts Create no new hazards - must not have shear points,

jagged edges or unfinished surfaces Create no interference - must not prevent worker from

performing the job quickly and comfortably Allow safe lubrication - if possible, be able to lubricate the

machine without removing the safeguards

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Where machine hazards occur:

Point of operationMechanical power transmissionOther moving parts

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Machine Hazards

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Machine Guarding

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In-Running Nip Points

Belt and pulley

Chain and sprocket

Rack and pinion

Rotating cylinders

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Methods of machine safeguarding

Physical guardsDevicesLocation/Distance

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Methods of Machine Safeguarding

Guards fixed interlocked adjustable self-adjusting

Devices presence sensing pullback restraint safety controls (tripwire cable,

two-hand contol, etc.) gates

Location/distance Feeding and ejection methods

automatic and/or semi-automatic feed and ejection

robots Miscellaneous aids

awareness barriers protective shields hand-feeding tools

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Guards

FixedInterlockedAdjustableSelf-adjusting

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Fixed Guard

Provides a barrier - a permanent part of the machine, preferable to all other types of guards.

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Interlocked Guard

When this type of guard is opened or removed, the tripping mechanism and/or power automatically shuts off or disengages, and the machine cannot cycle or be started until the guard is back in place.

Interlocked guard on revolving drum

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Adjustable Guard

Provides a barrier which may be adjusted to facilitate a variety of production operations.

Bandsaw blade adjustable guard

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Self-Adjusting Guard

Provides a barrier which moves according to the size of the stock entering the danger area.

Circular table saw self-adjusting guard

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Safeguarding devices

Presence sensingPullbackRestraintSafety controls and tripsGates

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Pullback Device

Utilizes a series of cables attached to the operator’s hands, wrists, and/or arms

Primarily used on machines with stroking action

Allows access to the point of operation when the slide/ram is up

Withdraws hands when the slide/ram begins to descend

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Pullback Device (cont’d)

Hands in die, feeding Point of operation exposed Pullback device attached

and properly adjusted

Die closed Hands withdrawn from

point of operation by pullback device

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Restraint Device

Uses cables or straps attached to the operator’s hands and a fixed point

Must be adjusted to let the operator’s hands travel within a predetermined safe area

Hand-feeding tools are often necessary if the operation involves placing material into the danger area

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Safety Tripwire Cables

Device located around the perimeter of or near the danger area

Operator must be able to reach the cable to stop the machine

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Two-Hand Control

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Requires constant, concurrent pressure to activate the machine

The operator’s hands are required to be at a safe location (on control buttons) and at a safe distance from the danger area while the machine completes its closing cycle

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Gate

Movable barrier device which protects the operator at the point of operation before the machine cycle can be started

If the gate does not fully close, machine will not function

Gate Open Gate Closed

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Safeguarding by Location/Distance

Locate the machine or its dangerous moving parts so that they are not accessible or do not present a hazard to a worker during normal operation

Maintain a safe distance from the danger area

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Automatic Feed(shown on power press)

Transparent EnclosureGuard

Stock FeedRoll

DangerArea

Completed Work

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Robots

Machines that load and unload stock, assemble parts, transfer objects, or perform other tasks

Best used in high-production processes requiring repeated routines where they prevent other hazards to employees

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Protective Shields

These do not give complete protection from machine hazards, but do provide some protection from flying particles, splashing cutting oils, or coolants.

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Holding Tools

Used to place and remove stock in the danger area

Not to be used instead of other machine safeguards, but as a supplement

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Subpart O - Machinery and Machine Guarding

211 - Definitions212 - General requirements213 - Woodworking machinery 215 - Abrasive wheel machinery216 - Mills and calendars217 - Mechanical power presses218 - Forging machines219 - Mechanical power transmission

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1910.212

General Requirements for all Machines

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1910.212(a)(1)

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 the point of operation, in-going nip points, rotating parts, flying chips and sparks.

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1910.212(a)(3)(ii)

The point of operation of machines whose operation exposes an employee to injury, shall be guarded

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1910.212(a)(5)

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 1/2 inch.

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1910.212(b)

Machines designed for a fixed location shall be securely anchored to prevent walking or moving.

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1910.213

Woodworking Machinery Requirements

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1910.213(a)(9)

All belts, pulleys, gears, shafts, and moving parts shall be guarded in accordance with the specific requirements of 1910.219.

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1910.213(b)(1)

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.

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1910.213(b)(3)

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.

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Table Saws

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1910.213(c)(1)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. The hood and mounting shall be arranged so that the hood will automatically adjust itself to the thickness of and remain in contact with the material being cut without considerable resistance.

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1910.213(c)(2)

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.

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1910.213(c)(3)

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 throw it back toward the operator.

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1910.213(d)(1)

Each circular crosscut table saw shall be guarded by a hood which shall meet all the requirements of 1910.213(c)(1) for hoods for circular resaws.

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Radial Arm Saws

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1910.213(i)(1)

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

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1910.213(r)(4)The mention of specific machines in

paragraphs (a) thru (q) and this paragraph (r) of this section, inclusive, is not intended to exclude other woodworking machines from the requirements that suitable guards and exhaust hoods be provided to reduce to a minimum the hazard due to the point of operation of such machines.

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1910.213(s)(7)

All cracked saws shall be removed from service.

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1910.215

Abrasive-Wheel Machinery

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1910.215(a)(4)

Work rests shall be adjusted closely to the wheel with a maximum opening of one-eighth inch to prevent the work from being jammed between the wheel and the rest, which may cause wheel breakage.

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1910.215(b)(9)

The distance between the wheel periphery and the adjustable tongue or the end of the peripheral member at the top shall never exceed one-fourth inch.

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1910.215(d)(1)

Immediately before mounting, all wheels shall be closely inspected and sounded by the user (ring test) to make sure they have not been damaged.

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Abrasive Wheel Machinery

The distance between the wheel periphery and the adjustable tongue must never exceed 1/4-inch.

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1910.217

Mechanical Power Presses

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1910.217(a)(5)

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.

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1910.217(b)(4)

The pedal mechanism shall be protected to prevent unintended operation.

A pad with a nonslip contact area shall be firmly attached to the pedal.

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1910.217(b)(6)A two-hand trip shall have the individual

operator’s hand controls protected against unintended operation and be arranged to require use of both hands.

Two-hand trip systems on full revolution clutch machines shall incorporate an antirepeat feature.

If two hand trip systems are used on multiple operator systems, each operator shall have a separate set of controls.

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1910.217(b)(7)

Two-hand controls must incorporate an anti repeat feature, require use of both hands, be protected against unintended operation, have one set of controls for each operator.

If foot control is provided, the selection between hand and foot control must be supervised by the employer.

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1910.217(c)(1)

It shall be the responsibility of the employer to provide and insure the use of point of operation guards or properly applied and adjusted point of operation devices on every operation performed on a mechanical power press. See Table O-10.

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1910.217(e)(1)

It shall be the responsibility of the employer to establish and follow a program of periodic and regular inspections of power presses.

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1910.217(e)(3)

It shall be the responsibility of the employer to insure the original and continuing competence of personnel caring for, inspecting, and maintaining power presses.

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1910.219

Mechanical Power-Transmission Apparatus

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1910.219(b)(1)

Flywheels located so that any part is 7 feet or less above the floor or platform shall be guarded.

Wherever flywheels are above working areas, guards shall be installed having sufficient strength to hold the weight of the flywheel in the event of a shaft or wheel mounting failure.

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1910.219(c)

Horizontal, vertical, and inclined shafting must be enclosed.

Projecting shaft ends shall present a smooth edge and end and shall not project more than 1/2 the diameter of the shaft unless guarded by non rotating cap or safety sleeves.

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1910.219(d)

Pulleys 7ft. or less above the floor or platform must be guarded.

Pulleys with cracks or pieces broken out of rims shall not be used.

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Portable Power Tools - General Safety Precautions

1910.242(a)Employers responsibility

Safe condition of toolsIncluding personal tools

1910.242(b)Compressed air not used for cleaning except

where reduced to less than 30 p.s.i. and only when effective chip guarding and PPE.

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Power Tools

Classification by power sourceElectricPneumaticLiquid FuelHydraulicPowder Actuated

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Power Tools (cont.)

1910.243 (a)(1) – Portable Circular Saws Upper blade guard Lower blade guard

Automatically returns to starting position

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Power Tools (cont.)

1910.243(a)(2) Constant Pressure

SwitchSaws and Chainsaws

Lock-on control (single motion turnoff)

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Pneumatic Power Tools and Hose

1910.243(b)Tool Retainer – A tool retainer must be

installed on each piece of equipment where ejection could result

Airhose – Hose and hose connections must be designed for the pressure and service to which they are subjected

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Explosive Actuated Fastening Tools

1910.243(d)Must meet requirements in ANSI A10.3-

1970Operators and assistants must wear eye

protectionHead and face protection dependent on

working conditions

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Explosive Actuated Tools (Cont.)

Muzzle must have protective shield or guard at least 3 ½ inches in diameter.

Firing must be dependent on at least 2 separate and distinct operations.

Firing mechanism must prevent tool from firing during loading, while preparing, if dropped.

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Explosive Actuated Tools (Cont.)

Tools must not be loaded until just before intended firing.

Do not point at anyone!Fasteners not driven into hard/brittle or

easily penetrable materialTools not used in hazardous atmosphere

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Lawnmowers

243(e)Meet the requirements of ANSI B71.1-X1968