Machine Safety and Hazards

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Questions and Answers

What is a common hazard associated with rotating parts in machinery?

Burns from friction

Caught by rotating and tangentially moving parts (correct)

Being hit by fixed barriers

Electrical shock from power supply

Which of the following is NOT a requirement for machine guards?

Secured and durable

Be aesthetically pleasing (correct)

Prevent falling materials into moving parts

Prevent employee contact with hazardous moving parts

What type of motion creates a risk of being struck or caught in a pinch point?

Reciprocating motion

Rotating motion

Transverse motion (correct)

Circular motion

Which type of mechanical motion is primarily associated with the action of shearing materials?

Reciprocating motion Signup and view all the answers

What is the purpose of machine guards?

To minimize risks of injury from hazardous machine parts Signup and view all the answers

Which type of guard allows for adjustment by the operator?

Self adjusting guards Signup and view all the answers

Which of the following is an example of hazardous mechanical motion?

Cutting Signup and view all the answers

What is the primary function of a photoelectric light curtain in machinery?

To prevent dangerous motion Signup and view all the answers

What is the primary purpose of pullback devices in machine safety?

To hold the operator’s hands away from the machine Signup and view all the answers

Which of the following is NOT a component of the Hierarchy of Control Measures?

Emergency Response Teams Signup and view all the answers

What is a major cause of maintenance injuries related to equipment operation?

Failure to clear work areas before restarting Signup and view all the answers

What does the lockout/tagout system primarily aim to control?

Hazardous energy sources during maintenance Signup and view all the answers

What is the primary goal of machine safeguarding?

To prevent accidents and injuries Signup and view all the answers

Which type of hazardous energy is related to potential energy from stored resources?

Potential Signup and view all the answers

Which of the following is NOT a cause of machine related accidents?

Excessive lubrication Signup and view all the answers

Which mechanical hazard is associated with back and forth movements of machine parts?

Reciprocating Signup and view all the answers

What function do protective shields serve in machine operations?

Protect from flying debris and fluids Signup and view all the answers

Which option best describes the role of holder, jigs, and push sticks in machine safety?

To hold or guide materials safely during operation Signup and view all the answers

What type of nip point is formed by parts that rotate in opposite directions with parallel axes?

In-running nip point Signup and view all the answers

What is a lockout device used for in maintaining machine safety?

To hold an energy isolating device in a safe position Signup and view all the answers

Which of the following is an effect of machine related accidents?

Loss of productivity Signup and view all the answers

Where do mechanical hazards typically occur in a machine?

In power transmission apparatus, point of operation, and other moving parts Signup and view all the answers

What is an example of a hazard associated with rotating motions?

Rotating shaft with a set screw Signup and view all the answers

What is the purpose of implementing a Lockout-Tagout (LOTO) system?

To ensure equipment is properly shut down during maintenance Signup and view all the answers

What is the principal advantage of a fixed enclosing guard?

It always prevents access to the hazard area. Signup and view all the answers

Which of the following is NOT a requirement for effective interlocking guards?

Allow operation even if the interlock fails. Signup and view all the answers

When should the adjustment of an adjustable guard be made?

Only during setup. Signup and view all the answers

What function do presence sensing devices serve?

They detect the presence of opaque objects within their field. Signup and view all the answers

Which statement accurately describes a photoelectric light curtain?

It emits infrared light beams that create a protective curtain. Signup and view all the answers

What is the purpose of two-hand controls in machine operation?

They require the operator to hold both controls during hazardous strokes. Signup and view all the answers

Which safety device creates a barrier that adapts to the size of stock entering a hazard area?

Self-adjusting guard Signup and view all the answers

How do restraint devices function in a hazardous environment?

They use fixed points to restrict hand movement safely. Signup and view all the answers

Which of the following is NOT considered a type of lock-out device?

Capacitor release switch Signup and view all the answers

What is the primary purpose of a tag-out device?

To indicate machinery requires servicing Signup and view all the answers

Who is classified as an Authorized Employee during the Lockout/Tagout procedure?

An employee who locks or tags machines for maintenance Signup and view all the answers

Which step in the typical Lockout/Tagout procedure involves notifying affected employees?

Notify Signup and view all the answers

What should be done after the energy isolating device is locked out?

Verify stored or residual energy is dissipated Signup and view all the answers

If multiple energy sources are present, how should lockout devices be applied?

Apply one padlock for each safety disconnect device Signup and view all the answers

During the 'Isolate' step of the Lockout/Tagout procedure, what should be done?

De-activate the energy isolating devices Signup and view all the answers

Which of the following is incorrect about the roles in the Lockout/Tagout procedure?

Authorized Employees can operate the equipment after lockout Signup and view all the answers

Study Notes

Machine Safety

Machine safety is about preventing accidents when working with machines.
Safeguarding prevents loss of life, injuries, production, equipment damage, litigation, and time spent on accident investigations.
Machine safety is the safeguarding of any machine part that may cause injury.
A machine is an assemblage of parts that transmit forces, motion, and energy in a predetermined manner.
Machines can be simple or compound

Causes and Effects of Machine Accidents

Accidents occur from unwanted contact with moving machine parts, flying objects, machine malfunctions, and workpiece movement during production.
Machine accidents can result in severe injuries, loss of skilled workers, decreased productivity, and equipment damage.

Mechanical Hazards in Machines

Power Transmission Apparatus includes components like flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, sprockets, cranks, and gears.
The Point of Operation is where work is performed on the material (e.g., cutting, shaping, boring).
Other Moving Parts are any parts that move while the machine is working.

Hazardous Mechanical Motions

Rotating: Turning around on an axis or center.
Reciprocating: Back and forth movements of a machine part.
Transversing: Continuous straight line motion of a machine element in either direction.

Hazards Associated with Rotating Motions

Examples: Rotating couplings with projecting bolts, rotating shafts and pulleys with projecting keys and set screws, rotating pulleys with spokes and projecting burrs.
Three types of In-Running Nip Points: Parallel Axes, Tangential & Rotating and Fixed Parts.
Pinch Point/Nip Point Hazards occur when rotating parts move in opposite directions, between a rotating part and a tangentially moving part, or between a rotating part and a fixed part.

Hazards Associated with Reciprocating Motions

Punching: The danger is at the point of operation where stock is inserted, held, and withdrawn by hand.
Shearing: Involves applying power to a slide or knife to trim or shear materials.
Bending: Power is applied to a slide to draw stamp metal or materials.

Hazards Associated with Transverse Motion

Transverse Motion: Movement in a straight and continuous line (e.g., conveyor belt or belt sander).
This motion creates a hazard because a worker may be struck or caught in a pinch or shear point.

Hazards Associated with Cutting

Cutting can involve rotating, reciprocating, or transverse motions (e.g., milling and lathe machines).

Machine Guards

Guards are barriers that prevent access to hazardous areas.
They minimize the risk of injury from hazardous parts, materials being processed, or scrap.

Requirements for Machine Guards:

Prevent employee contact with hazardous moving parts.
Be secured and durable.
Prevent falling materials into moving parts.
Create no new hazards.
Not interfere with worker productivity.
Allow for proper and safe maintenance and lubrication.

Categories of Machine Guards

Preventing Access:* Fixed Enclosing Guards, Movable Guards with Interlocking Switches (mechanical, electrical, pneumatic), Adjustable Guards (Manually adjustable, self-adjusting).
Preventing Dangerous Motion: Photoelectric Light Curtains/Presence Sensing Device, Two-Hand Controls, Pullback Devices, Restraint Device.

Fixed Enclosing Guards

Attached to a fixed surface and enclose the hazard, preventing access.

Movable Guards with Interlocking Switches

Prevent machine motion until the guard is in place.
Interlocking can be mechanical, electrical, or pneumatic.
To be effective, interlocking guards must enclose the point of operation before operation, keep it enclosed before the hazardous motion ceases, and prevent operation of the machine if the interlock fails.

Adjustable Guards

Positioned for various operations or work.
Provide adequate protection when properly adjusted.

Self-Adjusting Guard

Provides a barrier that adjusts to the size of the stock entering the danger area.

Safety Devices

Devices designed to protect workers' hands or other body parts from hazardous motion.
Examples: Photoelectric Light Curtains, Two-Hand Controls, Pullback Devices, Restraint Devices.
Pressure Sensitive Safety Mats and Pressure Sensitive Edges are also used to prevent dangerous motion.

Photoelectric Light Curtain

Emits a curtain of infrared light beams in front of the hazard area.
If a beam is blocked, the control circuit sends a stop signal to the machine.

Two-Hand Controls

Require the operator to hold both controls down during the hazardous part of the machine's stroke.

Restraint Devices

Use cables or straps attached to the operator's hands and a fixed point.
Must be adjusted to allow the operator's hands to travel within a safe area.

Pullback Devices

Cable and wristlet systems that attach to an operator's hands and the machine's moving slide or ram.
Used on machines with reciprocating motions.

Emergency Stops

Emergency stop buttons and grabwire switches.

Protective Shields

Provide protection from flying particles, splashing cutting oils or coolants.

Holders, Jigs, Push Sticks

Tools used to hold, guide, and push materials during machine operation.

Hierarchy of Control Measures

Engineering Controls include fixed enclosing guards, movable guards, protection devices, safety devices.
Administrative Controls include information, procedures, instruction, training, supervision, Lockout/Tagout Procedure, signs.
Personal Protective Equipment (PPE).

Control of All Energy Sources Through Lockout/Tagout System

This emphasizes the importance of a proper lockout/tagout system in energy control.

Main Causes of Maintenance Injuries ("Fatal Five")

Failure to stop equipment.
Failure to disconnect from the power source.
Failure to dissipate residual energy.
Accidental restarting of equipment.
Failure to clear work areas before restarting.

Source of Hazardous Energy

Electrical: Uncontrolled current and voltage in electrical circuits.
Mechanical: Exposed crushing or cutting parts of equipment or loose parts.
Thermal: Steam or chemical reactions.
Potential: Stored energy due to gravity, hydraulics, pneumatics, vacuum, or springs.

Isolation of Hazardous Energy

Basic Concept: Each worker who can be exposed to unexpected energization or start-up is protected by an isolation device under their control.

Lock-Out/Tag-Out System (LOTO)

This system is the standard for controlling hazardous energy sources for maintenance of machines where unexpected startup or release of stored energy could cause injury.

Lock-Out Devices

Devices that utilize a lock to hold an energy isolating device in the safe position and prevent energizing the equipment.
Examples include blank flanges.

Types of Lock-Out Devices

Plug Locks, Ball Valve Lock-Out, Gate Valve Lock-Out, Group Lock-Out (hasp), Circuit Breaker Lock-Out, Blanks for hydraulic, pneumatic, and other pressurized systems.

Tag-Out Devices

Warning devices, such as a tag and a means of attachment.
Secured to an energy isolating device to indicate that the equipment cannot be operated until the tag is removed.

Roles in LOTO Procedure

Authorized Employee: An employee who locks or tags machines or equipment to perform maintenance or servicing.
Affected Employee: An employee whose job requires them to operate or work in an area where servicing is being performed under Lockout/Tagout.

Typical LOTO Procedure

NOTIFY: Notify affected employees about servicing or maintenance and the shutdown and lockout.
IDENTIFY: The authorized employee identifies the type, source, and magnitude of energy, understands the hazards, and knows the methods to control the energy.
SHUT-DOWN: If the equipment is operating, shut it down using the normal stopping procedure.
ISOLATE: Deactivate the energy isolating device(s) to isolate the equipment from the energy source(s).
LOCK-OUT: Lock out the energy isolating device(s) with assigned individual lock(s) and place a tag-out.
VERIFY: Dissipate or restrain stored or residual energy and verify the isolation of the equipment by operating the push button or normal operating controls.

Application of the Lock-Out

For multiple energy sources, apply one padlock for each safety disconnect device.
One padlock per person per equipment.

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Description

This quiz explores the crucial concepts of machine safety, focusing on the prevention of accidents in the workplace caused by machinery. It covers the causes and effects of machine accidents, as well as the mechanical hazards associated with power transmission components. Understanding these principles is essential for maintaining a safe working environment.