01/13/14

1

Subpart O

Machine Guarding

Introduction

Crushed hands and arms, severed fingers, blindness - the list ofpossible machinery-related injuries is as long as it is horrifying.Safeguards are essential for protecting workers from needlessand preventable injuries.

A good rule to remember is: Any machine part, function, orprocess which may cause injury must be safeguarded.

Where the operation of a machine can injure the operator or otherworkers, the hazard must be controlled or eliminated.

01/13/14

2

Causes of MachineAccidents

Reaching in to “clear” equipmentNot using Lockout/TagoutUnauthorized persons doing maintenance or using themachinesMissing or loose machine guards

Where MechanicalHazards Occur

Point of operationAll parts of the machine which move, such as:

flywheels, pulleys, belts, couplings, chains, cranks,gears, etc.feed mechanisms and auxiliary parts of the machine

In-running nip points

01/13/14

3

Point of Operation

That point where work isperformed on the material,such as cutting, shaping,boring, or forming ofstock must be guarded.

Rotating Parts

01/13/14

4

In-Running Nip Points

Belt andpulley

Chain andsprocket

Rack andpinion

Rotatingcylinders

Requirements forSafeguards

Prevent contact - prevent worker’s body or clothing fromcontacting hazardous moving partsSecure - firmly secured to machine and not easily removedProtect from falling objects - ensure that no objects can fall intomoving partsCreate no new hazards - must not have shear points, jagged edgesor unfinished surfacesCreate no interference - must not prevent worker fromperforming the job quickly and comfortablyAllow safe lubrication - if possible, be able to lubricate themachine without removing the safeguards

01/13/14

5

Methods of MachineSafeguarding

Guardsfixedinterlockedadjustableself-adjusting

Devicespresence sensingpullbackrestraintsafety controls (tripwire cable,two-hand control, etc.)gates

Location/distanceFeeding and ejection methods

automatic and/or semi-automaticfeed and ejectionrobots

Miscellaneous aidsawareness barriersprotective shieldshand-feeding tools

Fixed Guard

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

01/13/14

6

Interlocked Guard

When this type of guard is opened or removed, the trippingmechanism and/or power automatically shuts off ordisengages, and the machine cannot cycle or be started untilthe guard is back in place.

Interlockedguard onrevolving drum

Adjustable Guard

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

Bandsaw bladeadjustable guard

01/13/14

7

Self-Adjusting Guard

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

Circular table sawself-adjusting guard

Pullback Device

Utilizes a series of cablesattached to the operator’shands, wrists, and/or armsPrimarily used on machineswith stroking actionAllows access to the point ofoperation when the slide/ram isupWithdraws hands when theslide/ram begins to descend

01/13/14

8

Pullback Device (cont’d)

Hands in die, feedingPoint of operation exposedPullback device attached andproperly adjusted

Die closedHands withdrawn from pointof operation by pullbackdevice

Restraint Device

Uses cables or strapsattached to the operator’shands and a fixed pointMust be adjusted to let theoperator’s hands travelwithin a predetermined safeareaHand-feeding tools are oftennecessary if the operationinvolves placing materialinto the danger area

01/13/14

9

Safety Tripwire Cables

Device located aroundthe perimeter of or nearthe danger areaOperator must be able toreach the cable to stopthe machine

Two-Hand Control

Requires constant, concurrentpressure to activate themachineThe operator’s hands arerequired to be at a safelocation (on control buttons)and at a safe distance fromthe danger area while themachine completes itsclosing cycle

01/13/14

10

Gate

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

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

Gate Open Gate Closed

Safeguarding byLocation/Distance

Locate the machine or itsdangerous moving parts sothat they are not accessibleor do not present a hazardto a worker during normaloperationMaintain a safe distancefrom the danger area

01/13/14

11

Automatic Feed(shown on power press)

TransparentEnclosureGuard

Stock FeedRoll

DangerArea

Completed Work

Robots

Machines that load andunload stock, assembleparts, transfer objects, orperform other tasksBest used in high-production processesrequiring repeatedroutines where theyprevent other hazards toemployees

01/13/14

12

Protective Shields

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

Holding Tools

Used to place and removestock in the danger areaNot to be used instead ofother machine safeguards,but as a supplement

01/13/14

13

Some Examples of OSHA MachineGuarding Requirements . . . .

Guarding Fan Blades

When the periphery of the blades of a fan is less than 7 feetabove the floor or working level, the blades must beguarded with a guard having openings no larger than 1/2inch.

01/13/14

14

Abrasive WheelMachinery

Work rests on offhand grinding machines must be keptadjusted closely to the wheel with a maximum opening of 1/8-inch to prevent the work from being jammed between thewheel and the rest, which may result in wheel breakage.

Abrasive WheelMachinery

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

01/13/14

15

Power-TransmissionApparatus

Power-transmissionapparatus (shafting,flywheels, pulleys, belts,chain drives, etc.) lessthan 7 feet from the flooror working platform mustbe guarded.

Unguarded belt and pulley

Machine SafetyResponsibilities

Managementensure all machinery is properly guarded

Supervisorstrain employees on specific guard rules in their areasensure machine guards remain in place and are functionalimmediately correct machine guard deficiencies

Employeesdo not remove guards unless machine is locked and taggedreport machine guard problems to supervisors immediatelydo not operate equipment unless guards are in place

01/13/14

16

Training

Operators should receive training on the following:Hazards associated with particular machinesHow the safeguards provide protection and the hazards forwhich they are intendedHow and why to use the safeguardsHow and when safeguards can be removed and by whomWhat to do if a safeguard is damaged, missing, or unable toprovide adequate protection

Summary

Safeguards are essential for protecting workers fromneedless and preventable machinery-related injuriesThe point of operation, as well as all parts of themachine that move while the machine is working, mustbe safeguardedA good rule to remember is: Any machine part,function, or process which may cause injury must besafeguarded