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Machine Guarding

Machine Guarding

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Machine Guarding

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  1. Machine Guarding Ringling College of Art & Design Department of Environmental Health and Safety

  2. Introduction • This online training course provides general information on machine guarding. All machine operators must complete this training and the quiz. • Specific information on machine hazards are provided by each department. • The course introduces the different methods of machine guarding, hazardous motions and actions, requirements for guards, and examples of guarding.

  3. Introduction • Machine guarding prevents body parts and objects from coming into contact with dangerous parts of machinery. • Crushed hands and arms, severed fingers, blindness - the list of possible machinery-related injuries is as long as it is horrifying. Safeguards are essential for protecting workers from needless and preventable injuries and deaths. • A good rule to remember is: Any machine part, function, or process which may cause injury must be safeguarded.

  4. Introduction • Machine guards differ for every machine due to the varying physical characteristics of machinery. • Machine guarding is required by OSHA (29 CFR 1910.212) for any machine that has the potential of causing an injury.

  5. General requirements • Machines have four main general requirements: • Electrical power and controls • Each machine must be equipped with a master switch that can be locked and/or tagged during repair or maintenance operations. • Power controls and operating controls must be located within easy reach of the operator. • A trip device must be provided on machinery where injury might result if motors were to restart after power failures. This prevents the machine from operating when electric service is restored. • Main "kill" switches should be centrally installed, easily identified and accessible to operators or shop supervisors / co-workers for use in interrupting power in emergency situations.

  6. General requirements • Guarding • Appropriate guards must be provided to protect the operator and others in the area from hazards. • No employee or student shall operate and/or cause to be operated, any machinery without proper protective devices in place. • Combs (feather boards) or suitable jigs must be provided for use when a standard guard cannot be used. • The operator should never perform layout, assembly or set-up work on the table/work area when the machine is running.

  7. General requirements • Personal Protective Equipment • Personal protective equipment may still be required; closed toed shoes, eye and hearing protection are frequently necessary. • Heavy aprons are encouraged when operating machinery that may produce kickbacks of stock. • Loose fitting clothing must not be worn. • Gloves, rings, neck chains and other jewelry must not be worn on moving machinery. • Long hair must be restrained.

  8. General requirements • Housekeeping • Metal slivers, sawdust and other debris should be cleaned from the machine using a brush or rag. Never use bare hands for the task. NEVER clean a machine while it is in motion. • If available, the dust collection system should be used at all times. Do not combine wood dust and metal filings. • To reduce the airborne dust levels, compressed air may be used for minor cleaning purposes only after the majority of the dust has been cleaned up manually and where the pressure is reduced to less than 30 P.S.I. (pounds per square inch) Eye protection must be worn while using compressed air to clean equipment.

  9. General requirements • Housekeeping (cont.) • Oily rags, waste, and other materials saturated with combustible substances must be disposed of in approved metal containers equipped with self-closing lids. • Local exhausts should be installed on machines where large amounts of dust are produced, such as sanders and planers. • Safety zones surrounding machines should be established and marked. Machines should be spaced to allow for the establishment of safety zones.

  10. Causes of machine accidents • Familiarity with machine – operator believes that they are skilled enough to use machine without the guard. • Reaching in to “clear” equipment. • Unauthorized person using machine. • Not using lock-out / tag-out – during maintenance. • Lack of concentration.

  11. Components of machines • A machine consists of three basic mechanical components: • Point of operation • Power transmission device • Other moving parts • NOTE: Even though machines have three basic components, the guarding requirements will differ on machinery.

  12. Components of machines • Point of Operation • Where the work is performed on the material (i.e. cut / shear). • Must be guarded. Point of Operation

  13. Components of machines • Power transmission device • This is the mechanical component that transmits energy to the part of the machine that performs the work (i.e. belt / pulley / flywheel). Power Transmission Device

  14. Components of machines • Other moving parts • Other moving parts (spindle and chuck on a drill press) of the machine that move while the machine is operating. Other Moving Parts

  15. Hazardous motions & actions • Machine guards must protect from hazardous motions and hazardous actions. • Hazardous motions include: • Rotating motion • Reciprocating motion • Transverse motion • In-running nip points (pinch points)

  16. Hazardous motions & actions • Rotating motion - circular motion • Rotating parts can “grab” clothing, hair or a body part and force it into a dangerous area. • Examples include flywheels, rotating shaft end and meshing gears.

  17. Hazardous motions & actions • Reciprocating motion • A back and forth motion or up and down motion that can strike or pin someone between a moving part and a fixed object. Forming machine

  18. Hazardous motions & actions • Transverse motion • A movement in a straight and continuous line. • Examples include conveyor belt and belt sander.

  19. Hazardous motions & actions • In-running nip points – 3 types • Parts can rotate in opposite directions, while their axes are parallel to each other. • A rotating part and a tangentially moving part. • Rotating part and fixed part which can create a shearing, crushing or abrading action. Rotating cylinder Chain and sprocket Abrasive wheel & work rest

  20. Hazardous motions & actions • Hazardous actions include: • Cutting action • Punching action • Shearing action • Bending action

  21. Hazardous motions & actions • Cutting action – hazards exist at the point of operation and also from flying chips or ejected materials. Drill press Router

  22. Hazardous motions & actions • Punching action – power is applied to a slide (ram) for the purpose of blanking, drawing or stamping materials. Power press

  23. Hazardous motions & actions • Shearing action – power is applied to a slide or knife used to trim or shear materials. Guard Shear Metal shear with guard Shearing action

  24. Hazardous motions & actions • Bending action – power is applied to a slide to draw, turn or stamp materials. Tube bender Bend sheet metal

  25. Safeguarding requirements • Machine guards must meet or exceed the following 6 OSHA requirements: • Prevent contact • Be secure • Protect from falling objects • Does NOT create a new hazard • Does NOT create an interference • Allows for safe lubrication

  26. Safeguarding requirements • Prevent contact • Prevent workers body or clothing from contacting the hazardous moving parts. • Be secure • Firmly secured to the machine. • Not easily removed from machine. • Made of durable material that will withstand the conditions of normal use. • A safeguard that can easily be made ineffective is no safeguard at all.

  27. Safeguarding requirements • Protect from falling objects • Ensure that no objects can fall into moving parts. • A small tool dropped into a machine could become a projectile causing an injury. • Does NOT create a new hazard • Must not have shear points, jagged edges or unfinished surfaces. • Edges of guards must not have sharp edges.

  28. Safeguarding requirements • Does NOT create an interference • Must not prevent worker from performing the job quickly and comfortably. A safeguard that impedes a workers performance may be overridden or disregarded. • Proper safeguarding can enhance efficiency, since it relieves apprehension about injury. • Allows for safe lubrication • If possible, be able to lubricate the machine without removing the safeguards. • Locating oil reservoirs outside the guards with lines leading to the lubrication point will reduce requirement to enter hazardous area.

  29. Methods of safeguarding • Machine guarding decisions should be made in the following order (hierarchy): • Design out or eliminate the hazard • Physically “engineer out” the exposure to the hazard • Guard the hazard — personal protective equipment may also be required • Use warning devices, or make the danger clearing apparent • Use warning signs • Use safe working practices and procedures

  30. Methods of safeguarding • We will review the following types of safeguarding: • Guards • Devices • Location / Distance • Feeding and ejection methods • Miscellaneous aids

  31. Safeguarding - Guards • There are four main types of guards: 1Fixed guard • Provides a barrier • A permanent part of the machine • Preferable to all other types of guards; best protection for guarding.

  32. Safeguarding - Guards 2Interlocked guard • When the guard is opened or removed, the tripping mechanism and or power automatically shuts off or disengages. • The machine cannot cycle or be started until the guard is back in place. Interlocking guard on revolving drum

  33. Safeguarding - Guards 3Adjustable guard • Provides a barrier which may be adjusted to facilitate a variety of production operations. • Subject to human error. Bandsaw blade adjustable guard

  34. Safeguarding - Guards 4Self adjusting guard • Provides a barrier which moves according to the size of the stock entering the danger area. • Avoids the potential for human error. Self adjusting guard on table saw

  35. Safeguarding - Devices • Devices prevent the operator from making contact with the point of operation. • This can be achieved with a pullback or restraint device that allows the operator’s hands to travel within a predetermined safe area.

  36. Safeguarding - Devices • Other devices include tripwire cables located around the perimeter of or near the danger area. • A two-hand control requires constant concurrent pressure to activate the machine.

  37. Safeguarding - Location • Locate the machine or its dangerous moving parts so that they are not accessible or do not present a hazard to a operator. • Maintain a safe distance from the danger area.

  38. Safeguarding – Feeding • Feeding and ejection methods include automatic and / or semi-automatic feed and ejection techniques. Material is fed into the machine eliminating the need for the operators involvement. • Other guards are required for operators protection. Transparent enclosure guard Stock feed roll

  39. Safeguarding – Misc. Aids • 3 miscellaneous aids will be discussed: 1Protective shields These do NOT give complete protection from machine hazards, but do provide some protection from flying particles, splashing cutting oils or coolants.

  40. Safeguarding – Misc. Aids 2Hand feeding tools • For placing and removing materials to prevent the operator placing a hand in the danger zone. • These must be used in conjunction with other required machine guard/s. Example, a push stick used in conjunction with a self adjusting guard on a table saw. Push block Fingerboard Push stick

  41. Safeguarding – Misc. Aids 3Awareness barriers • Serves as a reminder to a person that they are approaching the danger area. The barrier does NOT prevent the person from entering the danger area, but calls their attention to it. • Should NEVER be the only method of “guarding” an area as it is not considered an adequate means of prevention. Example, a high visibility tape.

  42. Construction - machine guarding • Most machine guards are provided with the equipment or can be purchased from the manufacturer. • Advantages: The guard conforms to the design and function of the machine and it can strengthen the machine through its design or serve an additional function. Chop saw Paper cutter

  43. Construction - machine guarding • When a guard cannot be purchased from the manufacturer, one may be user built providing: • It is fabricated to function effectively and • It meets the specifications for guarding of the specific machine. • NOTE Just because a guard is not specifically made for a machine, this does NOT mean that a guard does not have to be in place. Machine guarding is required on ALL machinery where a risk of an injury exists. Before and After

  44. Machine maintenance & repair • During servicing or maintenance the following 6 steps must be followed: • Notify all affected employees (usually machine or equipment operators or users) that the machine or equipment must be shut down to perform some maintenance or servicing; • Stop the machine; • Isolate the machine or piece of equipment from its energy source;

  45. Machine maintenance & repair • During servicing or maintenance the following 6 steps must be followed: (cont.) • Lock out and / or tag out the energy source; • Relieve any stored or residual energy; and • Verify that the machine or equipment is isolated from the energy source.

  46. Machine maintenance & repair • Although the 6 steps are a general rule, there are exceptions when the servicing or maintenance is: • not hazardous for an employee, • when the servicing which is conducted is minor in nature, • done as an integral part of production, and the employer utilizes alternative safeguards which provide effective protection as is required by 29 CFR 1910.212 or other specific standards.

  47. Machine maintenance & repair • When the servicing or maintenance is completed, there are specific steps which must be taken to return the machine or piece of equipment to service. These steps include: • Inspection of the machine or equipment to ensure that all guards and other safety devices are in place and functional, • Checking the area to ensure that energization and start up of the machine or equipment will not endanger employees,

  48. Machine maintenance & repair • When the servicing or maintenance is completed, there are specific steps which must be taken to return the machine or piece of equipment to service. These steps include: (cont.) • Removal of the lockout devices, • Reenergization of the machine or equipment, and • Notification of affected employees that the machine or equipment may be returned to service.

  49. Machine maintenance & repair • If it is necessary to oil machine parts while the machine is running, special safeguarding equipment may be needed solely to protect the oiler from exposure to hazardous moving parts. • Maintenance personnel must know which machines can be serviced while running and which can not. • The danger of accident or injury is greatly reduced by shutting off and locking out all sources of energy.

  50. Lock out / Tag out • Lock out / Tag out (control of hazardous energy) is an integral part of workplace safety. When machine guarding must be removed for maintenance, specific procedures must be followed. • Lock out / Tag out is a separate training program. If training is required contact the EHS department. • NOTE: See the Colleges Lock out / Tag out procedure and training information on the EHS website.