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Machine Guarding

Julian Kalac, P.EngJune 11, 2013

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Scenario• Printing press• 42 year old operator with 20 years exp.• Pinch point – 150psi• Distance from pinch point to safety stop

– 8 feet• No guards in place • Operator goes to remove a paper jam……..

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Result• Hospitalized for 1 week• Rehabilitation for 4-6 months• Severed tendons & nerves• Laceration to bone• Missing nerves & tendons• Loss of sensation• Loss of range or motion• Finger tips permanently bent

*These are onlyThe physical problems

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Any machine part, function, or process which may cause

injury must be safeguarded

Rule to Remember

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New Guardsfor Printing Press

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Types of Hazardous Mechanical Motions

and Actions• Rotating (including in-running nip points)• Reciprocating• Transverse

• Cutting• Punching• Pinching• Shearing• Bending

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Rotating Motion• Common rotating mechanisms

– Collars– Couplings– Cams– Clutches– Flywheels– Shaft ends– Spindles– Horizontal/vertical shafting

Dangerous moving parts in these basic areas require safeguarding:

1. Point of operation

2. In running nip points

3. Pinch points

4. Power transmission

5. Other moving parts

Where Dangerous Mechanical Hazards Occur

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Types of Machine Guards• Guards

– Fixed– Interlocked– Adjustable– Self-adjusting

• Devices– Presence sensing

• Photoelectrical (optical)• Radio frequency (capacitance)• Electromechanical

Machine Guards• Machines guards are there to protect from

exposed hazards• Guarding MUST never be removed unless

under supervision and locked out• If a Guard is missing notify your supervisor

immediately • Never bi-pass the guarding!

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Types of Machine Guards• Devices (cont’d)

– Pullback– Restraint– Safety controls

• Safety trip control– Pressure-sensitive body bar– Safety trip rod– Safety tripwire cable

• Two-hand control• Two-hand trip

– Gates• Interlocked• Other

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

Parts rotating in opposite direction

In-running nip point hazards

Rotating and tangentially moving parts

Rotating Parts

Point of contact between a chain and a sprocket

Examples of 3 Types of Motion

Rotating and fixed parts

Transverse motion

Rotating and tangential motion

Grinder Safety

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Grinder Safety (cont)

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Cutting Saws

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Point of contact Blade not guarded

Max Gap Allowable gaps Grinder

Guarded vs Ungarded Saw

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PINCH POINTS

LAMINATOR GUARDING

Interlocked Guarding

Mesh Guarding

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Adjustable GuardProvides 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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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

Example #1 Slitter guarding using guards

Front view of guard

Example #1 SLITTER GUARDING USING MECHANICAL GUARDS

Example #2 Slitter guarding using light curtains

Example #2 Slitter guarding using light curtains

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Not Guarded

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Guarded

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Machine Safety Responsibilities

• Management– ensure all machinery is properly guarded

• Supervisors– train employees on specific guard rules in their areas– ensure machine guards remain in place and are functional– immediately correct machine guard deficiencies

• Employees– do not remove guards unless machine is locked and tagged– report machine guard problems to supervisors immediately– do not operate equipment unless guards are in place

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Training Questions

• Why must machines be guarded?• What are the machine hazards ?• When can you remove a guard?• What to do if a guard is missing or

damaged?

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Any machine part, function, or process which may cause

injury must be safeguarded

Rule to Remember

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QUESTIONS???