Machine Safety Training

• Machine safety involves safeguarding machine parts that could cause injury
• Machine safety is accident prevention while working with machinery

Objectives of Machine Safety Training

• Understand the causes and effects of machine-related accidents
• Learn different ways of ensuring machine safety
• Be able to explain the LOTO (Lockout/Tagout) system

What is a Machine?

• A machine is an assembly of parts designed to transmit forces, motion, and energy in a predetermined manner
• Machines can be simple or compound

Importance of Machine Safety

• Prevents loss of life
• Prevents severe accidents and serious injuries
• Prevents loss of productivity
• Prevents damage to equipment
• Prevents possible litigations
• Prevents time spent on accident investigations and statutory requirements

Causes of Machine-Related Accidents

• Physical contact with moving parts
• Objects flying from the machine
• Machine malfunction, including mechanical and electrical failures
• Workpiece movement during forming or cutting

Effects of Machine-Related Accidents

• Can cause severe injuries like amputation
• Loss of a trained and skilled employee
• Decreased productivity
• Damaged equipment

Mechanical Hazards

• Power Transmission Apparatus
  • Contains components of the mechanical system that transfer energy
  • Common components: flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, sprockets, cranks, and gears
• Point of Operation
  • This is the area on a machine where it performs work on material such as cutting, shaping, boring, or forming
• Other Moving Parts
  • Encompasses all machine parts that move while the machine is operating

Hazardous Mechanical Motions

• Rotating – motion around an axis or center
• Reciprocating – back and forth movement of a machine part
• Transversing – continuous straight-line motion of a machine element

Hazards Associated With Rotating Motions

• Projecting keys, set screws, spokes, and burrs
• Can cause entanglement
• Flying chips and sparks

Types of In-Running Nip Points

• Parallel Axes: Parts rotate in opposite directions with parallel axes to each other
• Tangential: Points created between rotating and tangentially moving parts (belt and pulley, chains and sprocket)
• Rotating and Fixed Part: Screw conveyor, flywheels, grinding wheel

Hazardous Mechanical Motions

• Punching: Danger at the point of operation where stock is inserted, held, and withdrawn by hand
• Shearing: Applying power to a slide or knife to trim or shear materials
• Bending: Power applied to a slide to draw or stamp metal or materials
• Cutting: Using rotating, reciprocating, or transverse motions on milling and lathing machines
• Transverse motion: Movement in a straight, continuous line that creates a hazard, like a pinch point

Machine Guards

• Barriers that block entry into a hazard area
• Intended to minimize injury risks to operators from hazardous parts, materials being processed, or scrap

Requirements for Machine Guards

• Prevent employee contact with hazardous moving parts
• Secured and durable
• Prevent materials from falling into moving parts
• Create no new hazards
• Not to 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
  • Adjustable guards
    • Manually Adjustable
    • Self-Adjusting
• Preventing Dangerous Motion
  • Photoelectric light curtains/Presence sensing device
  • Two hand controls
  • Pullback devices
  • Restraint device

Preventing Access

Fixed Enclosing Guards

• Attached to a fixed surface
• Encloses a hazard to prevent anyone from going over, around, under, or through it
• Always prevents hazard access

Movable Guards with Interlocking Switches

• Prevents machine motion until the guard is in place
• Effective interlocking guards must:
  • Enclose the point of operation before operation
  • Maintain enclosure until hazardous motion ceases
  • Prevent machine operation if the interlock fails

Adjustable Guards

• Positioned for various operations
• Provides adequate protection from hazards
• Only adjust during setup

Self-Adjusting Guard

• Barrier moves according to stock size

Preventing Dangerous Motion

Safety Device

• Any mechanical or electrical devices designed to protect a worker's hands or other body parts coming into contact with a hazardous motion of a machine

Presence Sensing Device

• A safety device designed, constructed, and arranged to create a sensing field, area, or plane that will detect the presence of an opaque object in its field

Photo Electric Light Curtain

• Emits a "curtain" of harmless infrared light beams
• When beams are broken, the control circuit sends a stop signal

Two-Hand Controls

• Operator controls that require the operator to hold both controls down during the hazardous portion of the machine’s stroke

Restraint devices

• Uses cables or straps attached to the operator’s hands and a fixed point
• It should be adjusted to allow operators' hands to travel within a predetermined safe area

Pullback devices

• Holdout and restraint devices are cable and wristlet systems
• Attached to an operator’s hands to the machine’s moving slide or ram, or to a fixed object away from the point of operation
• Used on machines having reciprocating motions

Other Methods

• Emergency Stops
  • Emergency stop buttons
  • Grabwire switches
• Protective Shields
  • Protection from flying particles, splashing cutting oils or coolants
• Holder, Jigs, Push Sticks
  • Used to keep hands away from the point of operation

Hierarchy of Control Measures

• Engineering Controls
  • Fixed enclosing guards
  • Movable (interlocked) guards or protection devices
  • Protection appliances/other safety devices
• Administrative Controls
  • Training and supervision
  • Lockout/Tagout Program
  • Signs
• Personal Protective Equipment

Control of Energy Sources

Main Causes of Maintenance Injuries

• Failure to stop equipment
• Failure to disconnect from power source
• Failure to neutralize residual energy
• Accidental restarting of equipment
• Failure to clear work areas before restarting

Sources of Hazardous Energy

• Electrical: uncontrolled current and voltage
• Mechanical: crushing or cutting parts
• Thermal: steam or chemical reactions
• Potential: stored energy from gravity, hydraulics, pneumatics, vacuum or springs

Isolation of Hazardous Energy

• Each worker exposed to unexpected energization is protected by a personal isolation device

Lock-Out/Tag-Out System (LOTO)

• Standard for hazardous energy control
• Covers machine maintenance to prevent unexpected start-ups or energy release that could cause injury

Lockout Device

• A device such as a lock used for holding an energy-isolating device in a safe position to prevent equipment energization
• Included are blank flanges

Tagout Device

• A warning device like a tag securely fastened to an energy-isolating device
• Indicates the equipment cannot be operated until the tag is removed

Types of Lock-Out Devices

• Plug Locks
• Ball Valve Lock-out
• Gate Valve Lock-out
• Group Lock-out or Hasp
• Circuit Breaker Lockout
• Blanks for Hydraulic, pneumatic and other pressurized systems

Personnel Involved in LOTO

• Authorized Employee
  • Locks or tags machines for maintenance
• Affected Employee
  • Operates or works around servicing under Lockout/Tagout

Typical LOTO Procedure

• Notify affected employees of required servicing and shutdown
• Identify type, sources, and magnitude of energy
• Shut down equipment using normal procedures
• Isolate energy by de-activating isolating devices
• Lock out energy isolating devices with assigned locks
• Place a tag-out
• Dissipate or restrain stored energy
• Verify isolation by testing controls to confirm equipment will not operate

Application of the Lock-Out

• Use one padlock for each safety disconnect device on multiple energy sources
• One padlock per person per equipment
• Only authorized personnel can remove another's padlock who is on site

Summary

• Machine safety is preventing access to dangerous motions or preventing dangerous motions to access
• Machine safeguarding is generally accomplished by the use of machine guards and safety devices
• Use of the Lockout/Tagout system is an effective safety program when performing maintenance