Machine Guarding - National Institute of Environmental ...

MACHINE GUARDING

29 CFR 1910.211-222

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COURSE OBJECTIVES(Continued)

Accident Prevention.

Introduce Machine Guarding and Establish Its Role in Today’s Industry.

Introduce Basic Concepts and Techniques of Machine Safeguarding.

Provide Machine Safeguarding Skills for Maintenance Workers and Floor Supervisors.

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BASIS FOR THIS COURSE

Proper Machine Guarding Results in Accident ReductionElimination of Workplace Injuries & Illnesses Where PossibleReduction of Workplace Injuries & Illnesses Where PossibleDevelopment of Efficient Machine Guarding TechniquesOSHA Safety Standards Require:

Machines Be Properly GuardedTraining Be ConductedHazards and Precautions Be ExplainedA “Safety” Program Be EstablishedJob Hazards Be Assessed and Controlled

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APPLICABLE REGULATIONS

29CFR - Safety and Health Standards1910 - Industrial Safety

212 - General Requirements for All Machines213 - Woodworking Machinery214 - Cooperage Machinery215 - Abrasive Wheel Machinery216 - Mills and Calenders in the Rubber Industry217 - Mechanical Power Presses218 - Forging Machines219 - Mechanical Power Transmission Apparatus

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REMEMBER

Any machine part, function, or process which may cause injury must be safeguarded. When the operation of a machine or accidental contact with it can injure the operator or others in the vicinity, the hazards must be either controlled or eliminated.

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BASICS OF MACHINE GUARDING

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Where Mechanical Hazards Occur

The Point of Operation:Power Transmission Apparatus:Other Moving Parts:


Where Mechanical Hazards OccurThe Point of Operation: Where work is performed on the material, such as:

CuttingShapingBoringForming of stock LATHE

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Where Mechanical Hazards OccurPower Transmission Apparatus: All components of the mechanical system which transmit energy to the part of the machine performing the work.

300 RPM

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Where Mechanical Hazards OccurOther Moving Parts: Any part of the machine which moves while the machine is working.

Rotating partsFeed mechanismsReciprocating partsTransverse moving partsAuxiliary parts of the machine

±±±

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Hazardous Mechanical Motions and ActionsA wide variety of mechanical motions and actions may present hazards to the worker:

Rotating membersReciprocating armsMoving beltsMeshing gearsCutting teethAny parts that impact or shear

±±±

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Hazardous Mechanical Motions and Actions

Recognition of these hazards is the first step toward protecting workers from the danger they present.

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Hazardous Mechanical Motions

Motions

RotatingReciprocatingTransversing NIP POINT

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Hazardous Mechanical Actions

Actions

CuttingPunchingShearingBending

SHEARITESHEARITESHEARITECUTTING BLADESCUTTING BLADESCUTTING BLADES

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Rotating Motions

- Collars - Couplings - Cams- Clutches - Flywheels - Shaft ends- Spindles - Meshing gears - Horizontal shafts- Vertical shafts

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Rotating Motions

Rotating motions can grip clothing, and through mere skin contact force a limb into a dangerous position. The danger increases when projections such as set screws, bolts, nicks, abrasions, and projecting keys or set screws are exposed on rotating parts.

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BASICS MACHINE GUARDING OF


Reciprocating Motions

MOTIONRECIPROCATING

NIP POINT NIP POINT

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Reciprocating Motions

MOTIONRECIPROCATING

CAUGHT “IN-BETWEEN”OR “STRUCK-BY”


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Transversing Motions

TRAVEL

IN-RUNNING NIP POINTS


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Rotating Motions

NIP POINTS



Cutting Actions- Rotating motions- Reciprocating motions- Transversing motions

The danger of cutting action exists at the point of operation where finger, arm and bodily injuries can occur and where flying chips or scrap material can strike the head, particularly in the area of the eyes or face.

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Cutting Actions

BandsawsCircular sawsBoring machinesDrilling machinesTurning machines (lathes)Milling machines

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Punching ActionsPower pressesIron workers

20 TON

PRESS PRESSACME

PRESSESThe principle hazard occurs at the point of operation where stock is inserted, held or withdrawn.

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Shearing/Bending ActionsMechanical shearsHydraulic shearsPneumatic shears

DANGERCUTTING EDGE

PRESS PRESSSHEARITE

POWER SHEARS

SHEAR TERROR

The principle hazard occurs at the point of operation where stock is inserted, held or withdrawn.


Requirements for Safeguards

Be securely attachedCreate no new hazardsWithstand operational conditionsAllow for safe routine maintenanceAllow for safe operator adjustmentsWithstand environmental conditionsProvide protection from falling objectsPrevent contact with hazardous conditionsCreate no interference in the conduct of work

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Nonmechanical Hazard Considerations:

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Power sources are potential sources of dangerHow will guarding affect equipment operationEnsure proper grounding of systemsReplace frayed, exposed , or old wiringConsider effects of

- High pressure systems- Extreme temp conditions- Pulsation, vibration, or leaks- Noise or unwanted sounds- Cutting fluids and coolants


Operator Training Considerations:

Provide instruction and or hands-on trainingDiscuss the purpose of safeguardsCover associated hazards thoroughlyInvolve guard designers in the trainingDescribe how to properly use safeguards Describe how safeguards provide protectionDescribe circumstances for safeguard removalExplain what to do if safeguards are damagedExplain what to do if safeguards are missing

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Operator Training Considerations:

Defeating, altering, or removing safeguards can cause injury to co-workers and can leave the person performing such actions liable under the OSHA Act of 1970.

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Protective Clothing and Equipment Considerations:

ENGINEERING CONTROLSWork Station Design Tool Selection and DesignProcess Modification Mechanical Assist

ADMINISTRATIVE CONTROLSTraining Programs Job Rotation/EnlargementPacing Policy and Procedures

PERSONNEL PROTECTIVE EQUIPMENT Gloves WrapsShields Eye ProtectionNon-Slip Shoes Aprons

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Protective Clothing and Equipment Considerations:

Appropriate for the particular hazard(s)Maintained in good conditionProperly stored when not in useKept clean, fully functional, and sanitary

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METHODS OF MACHINE GUARDING

Guarding Method Dependant on:

Type of materialType of operationMethod of handlingSize or shape of stockPhysical layout of the work areaProduction requirements or limitations

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Manufacturers Recommendation:

Before beginning the process of guard procurement, design, or installation, the equipment manufacturer should be consulted for advice.

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Generally:

Power transmission apparatus is best protected by fixed guards that enclose the danger areas

Point of operation hazard guarding will vary

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Safeguards Are Grouped Under 5 Classifications:

GuardsDevicesLocations/DistanceFeeding and ejection methodsMiscellaneous aids

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Guards:

Guards are barriers which prevent access to danger areas, there are four general types:

Fixed guardsInterlocked guardsAdjustable guardsSelf-Adjusting guards

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Fixed Guards:

Fixed guards are a permanent part of the machine and not dependent upon moving parts to perform its intended function.

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Fixed Guards:

ADVANTAGES

Can be constructed to suit many different applicationsIn-plant construction is often possibleCan provide maximum protectionUsually requires minimum maintenanceCan be suitable to high production operationsCan be suitable to high repetition operations

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Fixed Guards:

LIMITATIONS

May interfere with visibilityCan be limited to specific operationsMachine adjustments and repair often require guard removal, thereby necessitating other means of protection for maintenance personnel

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Interlocked Guards:Interlocked guards are designed to automatically shut off or disengage the machine if the guard is opened or removed

AUTOMATICAUDIBLE ALARM

AUTOMATICVISUAL ALARM


Interlocked Guards:

Interlocked guards may use:

Electrical powerMechanical powerHydraulic powerPneumatic power

OR ANY COMBINATION OF POWER SOURCES

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Interlocked Guards:

Interlocks should not prevent “inching” by remote control if required

Replacing guards should not automatically restart the machine

IMPORTANT

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Adjustable Guards:Typically adjusted by the operatorAccommodate various sizes of stockMay require additional operator trainingAdjustable guards are typically used on:

BandsawsTablesawsPower pressesRoutersSimilar equipment

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Adjustable Guards:ADVANTAGES

Can be constructed to suit many specific applicationsCan be adjusted to admit varying sizes of stock

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LIMITATIONS

Hands may enter danger areaProtection may not be complete at all timesMay require frequent maintenance and or adjustmentThe guard can be defeated by the operatorMay interfere with visibility


Self-Adjusting Guards:Adjusts automatically to the workAccommodate various sizes of stockMay require additional operator trainingSelf-Adjusting guards are typically used on:

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Radial arm sawsTablesawsCircular sawsRoutersJointersSimilar equipment


Self-Adjusting Guards:

ADVANTAGES

Off-the-shelf guards are often commercially available

LIMITATIONS

Protection may not be complete at all timesMay require frequent maintenance and or adjustmentMay interfere with visibility

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Devices:

Devices fall into four general types:

Presence-Sensing devicesPullback devicesRestraint devicesSafety trip controls

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Devices:

Devices may perform one of several function:

Stop a machine if a body part is in dangerRestrain or withdraw a hand if it is in dangerRequire activation by the use of both handsProvide a barrier synchronized to the operation

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Presence-Sensing:PhotoelectricRadiofrequencyElectromechanical

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Restraint Devices:Uses Cables or StrapsAffixes to HandsMay Need Feeding ToolsAdjustment CriticalPositioning CriticalMaintenance CriticalTraining CriticalMust Restrain Body PartFrom Hazard!

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Safety Trip Controls:Body Trip BarsHand/Arm Trip BarsTripwire CablesPositioning CriticalAdjustment CriticalMaintenance CriticalTraining CriticalManual Reset NeededMust Stop MachineImmediately!


20 TON

PRESS PRESSACME

PRESSES

Two-Hand Control:Needs Constant PressureNeeds Concurrent PressurePositioning CriticalAdjustment CriticalMaintenance CriticalTraining ImportantMust Stop MachineImmediately!

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Location/Distance Safeguarding:Position Dangerous Areas of Machines So That They Are Not Assessable During Normal Operations. Examples Include:

Position Hazard Areas Against a WallLocate Hazards Out of Reach of OperatorsAdd Enclosures or Fences to Restrict AccessDesign Stock Feeding Openings Away From HazardsPosition the Operators Control Station Away From Hazards

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Guard Construction:

Many Machines Come With SafeguardsMany Older Machines Now Have Safeguards AvailableManufacturers Are Increasingly More Concerned With LiabilityCompanies Not Specialized in Guarding Issues

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Point-of-Operations Guards :Defined as: “The area on a machine where work is actually

performed upon the material being processed.”

Complicated by the Number and Complexity of Machines in UseMust Fully Safeguard the EmployeeMust Allow Production to ContinueHazard Analysis Is Usually RequiredIf Poorly Designed, Built, or Installed Guards May Create a Hazard Rather Than Eliminating One.

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Mechanical Power Transmission Apparatus Guards:

The only openings usually needed are for:

LubricationAdjustmentRepairInspection

300 RPM

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