Machine Safety and Workplace Hazards PDF

# Machine Safety - Department of Labor and Employment - Occupational Safety and Health Center ## Objectives 1. Identify causes and effects of machine related accidents 2. Enumerate ways of machine safeguarding 3. Explain the LOTO system ## What is a Machine? - An assemblage of parts that transmit...

# Machine Safety - Department of Labor and Employment - Occupational Safety and Health Center ## Objectives 1. Identify causes and effects of machine related accidents 2. Enumerate ways of machine safeguarding 3. Explain the LOTO system ## What is a Machine? - An assemblage of parts that transmit forces, motion and energy in a predetermined manner. - Can be simple or compound. ## Machine Safety Safeguarding any machine part that may cause injury. It is the prevention of accidents when working with machines. ## Importance of Machine Safety Prevents: - Loss of life - Severe accidents or serious injury - Loss of production - Equipment damage and repairs - Possible litigation - Having time spent on accident investigation and other statutory requirements. ## Causes of Machine Related Accidents 1. An individual making unwanted contact with a moving part of a machine 2. Something flying from the machine 3. A machine malfunction, including mechanical and electrical energy sources failure. 4. Workpiece movement during a forming or cutting process ## Effects of Machine Related Accidents - Can result to severe injuries. - Loss of trained and skilled employee - Loss in productivity - Damaged equipment. ## Where Mechanical Hazards Occur - **Power Transmission Apparatus**: - All components of the mechanical system that transmit energy to the part of the machine performing the work. - These components include flywheels, pulleys, belts, connecting rods, couplings, cams, spindles, chains, sprockets, cranks, and gears. - **The Point of Operation**: - That point where work is performed on the material, such as cutting, shaping, boring, or forming. - **Other Moving Parts**: - All parts of the machine which move while the machine is working. ## Hazardous Mechanical Motions - **Rotating**: Turning around on an axis or center. - **Reciprocating**: The 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 - Rotating coupling with projecting bolt. - Rotating shaft and pulley with projecting key and set screw. - Rotating pulley with spokes and projecting burr. ## 3 Types of In-Running Nip Points - **Parallel Axes**: Parts can rotate in opposite directions while their axes are parallel to each other. - **Tangential**: Nip points are also created between rotating and tangentially moving parts such as belt and pulley and chains and sprocket. - **Rotating and Fixed Part**: Such as screw conveyor, flywheels, abrasive (grinding) wheel. ## Pinch point/Nip Point Hazards (Examples) - Rotating parts in opposite direction - Between rotating part and tangentially moving part. - Between a rotating parts and fixed parts. ## Hazards Associated with Rotating Motions Other Hazards from Rotating Parts - "Caught by" - Flying particles - Sparks ## Hazardous Mechanical Motions ### Reciprocating Motions - **Punching**: The danger of this type of action occurs at the point of operation where stock is inserted, held and withdrawn by hand. ### Shearing - Involves applying power to a slide or knife in order to trim or shear metal or other materials. ### Bending - Bending action results when power is applied to a slide in order to draw stamp metal or materials. ## Hazards of Reciprocating Parts of Machines - A diagram depicting a worker near a reciprocating machine illustrates the risks associated with this type of motion. ## Hazardous Motions - **Transverse Motion**: This refers to movement in a straight and continuous line. This type of motion creates a hazard because a worker may be struck or caught in a pinch or shear point by the moving part. An excellent example of a transverse motion would be a conveyor belt or belt sander. ## Hazardous Mechanical Motions ### Cutting - May involve rotating, reciprocating, or transverse motions, such as milling and lathe machines. ## Machine Guards - Guards are barriers that prevent entry of an individual's hands or other body parts into a hazard area. - Installed to minimize the risk of injury to machine operators or other persons from hazardous machine parts, materials being processed, or scrap. ## Requirements for Machine Guards - Prevent employee contact with hazardous moving parts. - Secured and durable. - Prevent falling materials into moving parts. - Create no new hazards. - Must not interfere with worker productivity. - Should allow for proper and safe maintenance and lubrication. ## Category 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 - This type of guard is attached to a fixed surface and encloses the hazard. - When in place, it prevents anyone from going over, around, under or through it to the hazard. - The principal advantage of the fixed enclosing guard is that it always prevents access to the hazard area. ### Movable Guards with Interlocking Switches - Prevents machine motion until the guard is moved into place. - The interlocking method may be mechanical, electrical, pneumatic, or a combination of these. - To be effective, interlocking guards must: 1. Enclose the point of operation before the machine can be operated. 2. Keep the point of operation enclosed before the hazardous part of the machine motion ceases. 3. Prevent operation of the machine if the interlock fails. ### Adjustable Guards - This type of guard can be positioned to accommodate a variety of operations or work. - When properly adjusted it provides adequate protection from the hazard at the point of operation. - Adjustment of the guard should only be performed during setup. ### Self-Adjusting Guard: - Provides a barrier which moves according to the size of the stock entering the danger area. ## Preventing Dangerous Motion ### Safety Device - Any mechanical or electrical devices designed to protect a worker's hands or other body parts from coming into contact with a hazardous motion of a machine. ### Presence Sensing Device - A safety device which is designed, constructed, and arranged to create a sensing field, area, or plane that will detect in its field the presence of an opaque object. ### Photoelectric Light Curtain - These devices emit a "curtain" of harmless infrared light beams in front of the hazard area. - When any of the beams are blocked the light curtain control circuit sends a stop signal to the guarded machine. ## Preventing Dangerous Motion - An illustration showcasing a worker near a machine protected by a photoelectric light curtain. ## Preventing Dangerous Motion - Pressure sensitive safety mats. - Pressure sensitive edges. ## Preventing Dangerous Motion ### Two-Hand Controls - Two-hand controls are operator controls that require an operator to hold both controls down during the hazardous portion of the machine's stroke. ## Preventing Dangerous Motion ### Restraint Devices - Uses cables or straps attached to the operator's hands and a fixed point. - Must be adjusted to let the operator's hands travel within a predetermined safe area. ## Preventing Dangerous Motion ### Pullback Devices - Holdout and restraint devices are cable and wristlet systems that attach to an operator's hands and to the machine's moving slide or ram, or to a fixed object away from the point of operation. - They are usually used on machines having reciprocating motions. ## Emergency Stops - Emergency stop buttons. - Grabwire switches ## Protective Shields - Provides same protection from flying particles, splashing cutting oils or coolants. ## Holder, Jigs, Push Sticks - A diagram of various tools for holding, guiding, and pushing materials during machine operation, illustrating their role in machine safety. ## The Hierarchy of Control Measures - **Engineering Controls**: - Fixed enclosing guards. - Movable (interlocked) guards or protection devices. - Protection appliances/other safety devices. - **Administrative Controls**: - Provision of information, procedure, instruction, training & supervision. - Lockout/Tagout Procedure. - Signs. - **Personal Protective Equipment** ## Control of All Energy Sources Through Lockout/Tagout System - A dedicated section emphasizing 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 power source. - Failure to dissipate (bleed, neutralize) residual energy. - Accidental restarting of equipment. - Failure to clear work areas before restarting. ## Source of Hazardous Energy - **Electrical**: The uncontrolled current and voltage in electrical circuits. - **Mechanical**: Exposed crushing or cutting parts of equipment or loose parts. - **Thermal**: Such as steam or due to chemical reaction. - **Potential**: Stored energy that may be 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 of equipment, or release of stored energy is protected by an isolation device which is under his personal control. ## Lock-Out/Tag-Out System (LOTO) - The standard for the control of hazardous energy sources which covers maintenance of machines in which the unexpected start up of machines or release of stored energy could cause injury to employees. ## Lock-Out Devices - Lockout device: - Device that utilizes a positive means such as a lock to hold an energy isolating device in the safe position and prevents the energizing of an equipment. - Included are blank flanges. - An image showcasing a lock-out device commonly employed in machine safety. ## 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. - Several lock-out devices, ranging from plug locks to valve lock-outs, illustrating the variety of methods used to isolate energy sources. ## Tag-Out Devices - Tagout device: - A warning device, such as a tag and a means of attachment. - Can be securely fastened to an energy isolating device in accordance with an established procedure to indicate that the energy isolating device and the equipment being controlled can not be operated until the tag is removed. - Different types of tag-out devices, highlighting their use in machine safety procedures. ## Who are Involved 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 him/her to operate or work in an area where servicing is being performed under Lockout/Tagout. ## Typical LOTO Procedure 1. **NOTIFY**: Notify all affected employees that servicing or maintenance is required on an equipment and that it must be shut down and locked out. 2. **IDENTIFY**: The authorized employee shall identify the type, sources and magnitude of the energy that the equipment utilizes, shall understand the hazards of the energy, and shall know the methods to control the energy. 3. **SHUT-DOWN**: If the equipment is operating, shut it down by the normal stopping procedure. 4. **ISOLATE**: De-activate the energy isolating device(s) so that the equipment is isolated from the energy source(s). 5. **LOCK-OUT**: Lock out the energy isolating device(s) with assigned individual lock(s). Place a tag-out. 6. **VERIFY**: Stored or residual energy (such as that in capacitors, springs, elevated machine members, rotating flywheels, hydraulic systems, and air, gas, steam, or water pressure, etc.) must be dissipated or restrained. Verify the isolation of the equipment by operating the push button or other normal operating control(s) or by testing to make certain the equipment will not operate. ## Application of the Lock-Out - For multiple energy sources, apply one padlock for each safety disconnect device. - One padlock per person per equipment. No one is authorized to remove another's padlock while the person who owns the padlock is on site. - A visualization illustrating the principle of using a padlock to isolate a machine's power source during maintenance. ## Conclusion - 0% energy, 100% safety. - A twist of the key could keep you accident free. - Play it safe from head to toe; Off for fixing, on for go. - A machine will bite with all its might. So put a lock on its appetite. - Thank you for listening! ## Machine safety Program - An effective machine safety program must have the following: - Equipment/Machine inspection and maintenance program. - Installation of safety devices (guards, relief valves, provision for LOTO, interlocks, limit switches, etc) - Compliance to regulatory requirements and standards (e.g. mechanical permits, OSHS, etc) - Implementation of LOTO system. - Having a machine operation and safety procedures. - Machine alarm and warning signal system. - Equipment/machine safety signages. - Application of Job hazard Analysis. ## 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. - The lockout/tagout system is an effective safety program when performing maintenance activity. # Thank You for Listening! - Department of Labor and Employment - Occupational Safety and Health Center - Basic Occupational Safety and Health Training