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Accident Prevention Manual

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Title: Accident Prevention Manual


1
  • Accident Prevention Manual
  • for Business Industry
  • Engineering Technology
  • 13th edition
  • National Safety Council

Compiled by Dr. S.D. Allen Iske, Associate
Professor University of Central Missouri
2
CHAPTER 23
  • METALWORKING MACHINERY

3
Metalworking Machinery
  • Power-driven machines not movable by hand
  • Metalworking machinery is used to shape or form
    metal by cutting, impact, pressure, electrical
    techniques, chemicals techniques, or a
    combination of these processes.
  • Association for Manufacturing Technology (AMT)
    has classified 200 types of machines into five
    groups
  • Turning
  • Boring
  • Milling
  • Planing
  • Grinding
  • Other electrodischarge, electrochemical, laser,
    machining tools

4
Metalworking Machinery (Cont.)
  • Injuries
  • caused by unsafe working practices or incorrect
    procedures
  • insufficient training
  • inadequate supervision
  • injuries due to machine mechanical failures or
    operation after unsafe conditions develop are
    rare
  • Prevention of injuries
  • only qualified competent personnel should operate
  • properly maintaining and operating equipment
  • effective guarding devices
  • good housekeeping
  • good work habits

5
General Safety Rules
  • Emphasize safely operating metalworking
    machinery.
  • Establish written policy.
  • Restrict operation, adjustment, and repair of
    machine tool to authorized, experienced, and
    trained personnel.
  • Ensure proper power lockout/tagout.
  • Closely supervise all personnel during training.
  • Establish and maintain safe work procedures.
  • Prohibit shortcuts and chance taking.

6
General Safety Rules (Cont.)
  • When purchasing new equipment, make sure the
    specifications are applicable to all standards,
    codes, and regulations concerning guarding,
    electrical safety, and other safeguards
  • Inspect any modified equipment and make safety
    innovations before allowing operators to use the
    equipment.
  • Devote full-time attention to the work in
    progress.
  • Make supervisors responsible for the strict
    enforcement of this policy.
  • ANSI/NFPA 70 and ANSI C2 should govern
    installation of electrical circuits and switches.

7
General Safety Rules (Cont.)
  • Electrical controls on machine tools
  • Disconnect switch can be locked in OFF position
    to isolate the machine from power source.
  • Do not permit maintenance or repair on any
    machine until the disconnect switch serving the
    equipment has been shut off, padlocked in the OFF
    position, and tagged.

8
General Safety Rules (Cont.)
  • Rules for safely operating machine tools
  • Never leave machine tools running unintended,
    unless the machine has been designated to do so.
  • Never wear jewelry or loose-fitting clothing.
  • Keep long hair covered.
  • Wear eye protection.
  • Do not contaminate metal removal fluid.
  • Do not manually adjust and gauge work while
    machine is running.
  • Use brushes, vacuum equipment or special tools
    for removing chips. Do not use hands.
  • Use the proper hand tool for each job.
  • Know health and fire hazard of working with
    metals.

9
General Safety Rules (Cont.)
  • Safely removing chips, shavings, and cuttings
  • A major cause of accidents is use of
    high-pressure compressed air to blow chips,
    cuttings, or shavings from machines or workers
    clothing.
  • In cases where neither a brush or a vacuum is
    practical, it may be necessary to use air.
  • Isolate the machine tool operation so that nearby
    employees are not endangered.
  • Place chip guards around the machine to shield
    the operator.
  • Employees should wear PPE safety goggles, face
    shield, body clothing
  • Prohibit employees from using high-pressure
    compressed air to blow dust or dirt from clothing
    and hair.
  • One company has eliminated injuries caused by
    removing chips, shavings, or cuttings.
  • Employees wear leather palmed gloves and use a
    3-ft-long rod to pull shavings and cutting from
    the machines.

10
General Safety Rules (Cont.)
  • Personal protection
  • The operators safety depends on following safe
    working procedures and wearing proper protective
    clothing and equipment.
  • Wearing close-fitting clothing is important.
  • Many serious injuries and fatalities have
    resulted when neckties, loose shirtsleeves,
    gloves or other clothing have gotten caught in a
    belt and sheave, between gears, in a revolving
    shaft or revolving work piece held in the chuck.
  • Operators should not wear jewelry that might get
    caught in machinery.
  • Every operator should wear protective footwear.
  • Operators with long hair should wear caps,
    snoods, or hairnets.
  • Use splash guards, shields, PPE to minimize
    exposure to irritating cutting oils and mineral
    spirits used to clean parts.
  • Provide barrier creams and encourage personal
    hygiene measures.

11
Turning Machines
  • Shaping a rotating piece with a cutting tool,
    usually to give a circular cross section is known
    as turning. Engine lathes, turret lathes,
    chuckers, automatic screw machines.
  • Engine lathes
  • Only qualified personnel to operate
  • The following activities/situations are likely to
    result in injuries
  • Having contact with projections on work or stock
    faceplates, chucks, or lathe dogs
  • Being hit by flying metal chips
  • Hand braking the machine
  • Calipering and gauging the job while machine is
    running
  • Failing to keep the center holes of taper work
    clean and true and the lathes center true and
    sharp
  • Leaving the machine running unattended
  • Handling chips by hand
  • Attempting to remove the chips while the machine
    is running
  • Leaving the chuck wrench in the chuck
  • Catching rings, loose clothing, gloves, or rags
    for wiping or revolving parts

12
Turning Machines (Cont.)
  • Engine lathe preventive measures
  • Use faceplates and chucks without projections
    whenever possible.
  • Install a shield formed to the contour of the
    chuck or plate and hinged at the back.
  • Substitute safety-type lathe dogs for projective
    setscrews.
  • Chip shields help control flying chips.
  • These shields do not eliminate the need for
    protective eye equipment.

13
Turret Lathes and Screw Machines
  • Hazards associated with turret lathes and screw
    machines are similar to those listed for other
    lathes.
  • Additional hazards are caused by operators not
    moving the turret back as far as possible when
    changing or gauging work or using machine power
    to start the faceplate or chuck onto the spindle.
  • Operators fail to keep their hands clear of the
    turrets slide or permitting a hand, arm, or
    elbow to strike the cutter while adjusting or
    setting up.
  • Install splash shield, especially for automatic
    machines.
  • Enclosure shield over the chuck to confine hot
    metal chips and oil splashes.
  • Install chip breakers to protect against hand and
    arm injuries.

14
Spinning Lathes
  • A spinning lathe is a forming tool rather that a
    cutting tool.
  • Usually requires a skilled and qualified
    operator.
  • Unsafe practices
  • Inserting blanks and removing the processed part
    without first stopping the machine.
  • Failing to fully tighten the tailstock handle and
    risking that the blank will work loose or ruin
    the stock or tool.
  • Allowing the swarf (cutting, turnings, particles)
    to build up into a long coil when trimming copper
    and certain grades of steel.
  • Accidents (severed hands and severely cut arms)
  • Coil became snarled in an operators neck.
  • Operators should remove the tool when necessary
    to allow the swarf to break off.
  • Spinning lathes reach speeds from 500 to 2,000
    rpm.
  • Prevention of injuries lies in frequent
    inspection and maintenance of chucks. Inspect for
    cracks in tools or handles.

15
Boring Machines
  • Boring consists of cutting a round hole using a
    drill, boring cutter, or reamer.
  • Drilling machines are equipped with rotating
    spindles, handles, and chucks that carry pointed
    or fluted cutting tools.
  • Operations performed with drilling machines
    include
  • countersinking
  • reaming
  • tapping
  • facing
  • spot facing
  • routing

16
Drills
  • Drill press accidents are more likely to occur
    during unusual jobs because special jibs or vises
    for holding the work are not usually provided.
  • Radial drill accidents are frequently caused by
    incorrect manipulation.
  • Common hazards
  • Contacting the rotating spindle or the tool
  • Being struck by a broken drill
  • Using dull drills
  • Being struck by insecurely clamped work
  • Catching hair, clothing, or gloves in revolving
    parts
  • Sweeping chips, or trying to remove long spiral
    chips by hand
  • Leaving the key or the drift in the chuck
  • Being struck by a flying metal chip
  • Failing to replace the guard over the
    speed-change pulley or gears
  • When necessary guard the tool with a telescoping
    guard to cover the end of the tool.
  • A drill smaller that 1/8 in. in diameter will
    often break and cause injury.
  • A frozen tool may cause unclamped or insecurely
    clamped work to spin and injure the operator.
  • If chips are allowed to pile up, the drill might
    jam, with results similar to that of a frozen
    tool.

17
Boring Mills
  • Common causes of injuries in boring mill
    operations
  • being struck by insecurely clamped work or by
    tools left on or near the revolving table
  • catching clothing or rags for wiping in revolving
    parts
  • falling against revolving parts
  • calipering or checking work while the machine is
    in motion
  • allowing turnings to build up on the table
  • removing turnings by hand

18
Horizontal Boring Mills
  • Horizontal boring mills
  • The same accident prevention activities are
    effective on both table and floor types of
    horizontal boring mills.
  • While the machine is in motion, the operator
    should never attempt to make measures near the
    tool, reach across the table or adjust the
    machine or the work.
  • Frequently inspect clamps and blocking to make
    certain the clamping is positive. Always avoid
    makeshift setups.
  • Properly adjust by raising or lowering the boring
    mills head to avoid damage to the machine or
    injury to the operator.

19
Vertical Boring Mills
  • Vertical boring mills
  • Each mills table, particularly those tables 100
    in. or less in diameter, should have the rim
    enclosed in a metal band guard to protect the
    operator from being struck by the revolving table
    or projecting work.
  • If the table is flush with the floor, install a
    portable fence.
  • While the machine is in operation, the operator
    should never attempt to tighten the work, the
    tool, the caliper, nor measure the work, feel the
    edges of the cutting tool, or oil the mill.
  • The operator should never ride the table while it
    is in motion, except if necessary by procedure to
    observe the works progress.

20
Milling Machines
  • Machining a piece of metal by bringing it into
    contact with a rotating multi-edged cutter is
    milling.
  • This procedure is done by horizontal and vertical
    milling machines, by gear hobbers, profiling
    machines, circular and band saws and a number of
    other types of related machines.

21
Milling Machines (Cont.)
  • Causes of injuries
  • Failure to draw the job back to a safe distance
    when loading or unloading
  • Using a jig or vise that prevents close
    adjustment of the guard
  • Placing the jig or vise-locking arrangement in
    such a position that force must be exerted toward
    the cutter
  • Leaving the cutter exposed after the job has been
    withdrawn
  • Leaving hand tools on the workable
  • Failing to securely clamp the work
  • Reaching around the cutter or hob to remove chips
    while the machine is in motion
  • Removing swarf cuttings by hand instead of with a
    brush
  • Calipering or measuring the work while the
    machine is working
  • Using a rag to clean excess oil while the cutter
    is turning
  • Incorrectly storing cutters
  • Cleaning the machine while in motion
  • Misjudging clearances between the arbor or other
    parts
  • Wearing improper clothing or jewelry around
    milling machine

22
Basic Milling Machines
  • To guard the cutter, mount hand-adjusting wheels,
    for quick or automatic transverse on some models,
    on the shaft by either clutches or ratchet
    devices. In this way, the wheels do not revolve
    when the automatic feed is used.
  • The horizontal milling machine should have a
    splash guard and pans for catching ejected
    metalworking fluids or lubricants running from
    the tools.
  • When possible, make all cuts into the travel of
    the table rather than away from the direction of
    travel.

23
Metal Saws
  • Circular saws
  • They should have a hood guard at least as deep as
    the roots of the teeth.
  • The guard should automatically adjust itself to
    the thickness of the stock being cut.
  • Use a sliding stock guard when tube or bar stock
    is cut.
  • Guard the portion of the saw under the table with
    a complete enclosure that provides for disposal
    of the scrap metal.
  • Do not consider a guard as a substitute for eye
    protection.

24
Metal Saws (Cont.)
  • Swing saws
  • Adjust the length of the stroke so the blade will
    not pass the table at its most forward point.
  • Locate the control so the saw can be operated
    with the left hand when fed from the left or with
    the right hand if fed from the right.
  • Operator positioned to the side away from the
    moving table.
  • Band saws
  • Completely enclose the upper and lower wheels of
    metal-cutting band saws with sheet metal or a
    heavy, small-mesh screen mounted on angle-iron
    frames.
  • Provide access doors equipped with latches.
  • The length of the blade exposed should not be
    more than the thickness of the stock plus 3/16
    in.
  • On a hand-fed operation, take care at the end of
    a cut.
  • Use a push block not hands.

25
Gear Cutters
  • Gear cutters
  • When operating cutters and hobbers, both the tool
    and workpiece move.
  • Keep the point of operation guards simple and
    easily adjustable.
  • On operations where the workpiece is moved to the
    tool, a simple barrier guard, formed to cover the
    point of operation and sized to fit the workpiece
    is satisfactory.
  • Locate all controls for protection of the
    operator and ease of function.
  • Electrical discharge machinery (EDM)
  • This process is designed to perform a variety of
    machining operations.
  • This process makes simple or complex machining
    possible through hole boring or cavity sinking in
    any electrically conductive work material.

26
Electrical Discharge Machining
  • Discharge gases hazard
  • Operators and maintenance personnel should
    completely understand all the precautions before
    operating, setting up, running, or performing
    maintenance on EDM machines.
  • Failure to comply with instructions may result in
    serious or fatal injury.
  • The operator should be aware of the possibility
    of discharge gases igniting.
  • Turn off the electrical power to stop additional
    gas or hot metal particles from forming to
    extinguish a flame.
  • All discharge gases are flammable keep them away
    from sparks or flame.

27
Planing Machines
  • Planers machine metal surfaces.
  • The cutting tool is held stationary while the
    workpiece is moved back and forth underneath it.
  • With shapers classified as planing machines, the
    process is reversed.
  • The workpiece is held stationary while the
    cutting tool is moved back and forth.
  • Other machine tools classified as planing
    machines are slotters and broaches.

28
Planers
  • Accidents result from unsafe practices by
    inadequate training and supervision such as the
    following
  • placing hands or fingers between the tool and the
    workpiece
  • running the bare hand over sharp metal edges
  • measuring the job while the machine is running
  • failing to clamp the workpiece or tool securely
    before starting the cut
  • riding the job
  • having insufficient clearance for the workpiece
  • coming in contact with reversing feed dogs
  • failing to make sure the current is turned on
    before starting the machine.
  • unsafely adjusting the tool holder on the cross
    head
  • To avoid these accidents, install guards in
    planers. Cover the feed dogs on planers.

29
Shapers
  • Accidents with shapers are essentially the same
    as planers.
  • In addition, injuries from contact with
    projections on the workpiece or with projecting
    bolts or brackets.
  • Shaper operators should make sure the tool is
    set.
  • Remove the handle of the stroke-change screw
    before starting the shaper.
  • To prevent injury to the operator and workers
    nearby from flying chips, install guards.

30
Planers and Shapers
  • Slotters
  • Most serious accident is catching the fingers
    between the tool and the workpiece.
  • Fingers can be caught between the ram and the
    table when the ram is at the end of the
    downstroke.
  • Broaches
  • Rated capacity should be equal to or greater than
    the force required for the job.
  • Two-hand controls and install Emergency Stop.

31
Grinding Machines
  • Grinding machines shape material by bringing it
    into contact with a rotating abrasive wheel or
    disk.
  • Grinding includes
  • surface, internal, external cylindrical, and
    centerless operations, as well as polishing,
    buffing, honing, and wire brushing
  • Reference ANSI Standards B7.1 Use, Care and
    Protection of Abrasive Wheels and B11.9 Safety
    Requirements for the Construction, Care and Use
    of Grinding Machines

32
Grinding Machines (Cont.)
  • Hazards
  • Failure to use eye protection and eye shield
    mounted on grinder
  • Incorrectly holding the work
  • Incorrectly adjusting the work rest
  • Using the wrong type of wheel or disk
  • Grinding on the side of the wheel not designed
    for grinding
  • Taking too heavy a cut
  • Applying work too quickly to a cold wheel or disk
  • Grinding too high above the wheels center
  • Vibration and excessive speed that lead to
    bursting a wheel or disk
  • Contacting unguarded moving parts
  • Incorrect wheel dressing
  • Contacting unguarded moving parts
  • Using controls that are out of the operators
    normal reach
  • Using an untested, broken, or cracked grinding
    wheel
  • Using an abrasive blade instead of a grinder disk

33
Abrasive Disks and Wheels
  • An abrasive disk is made of bonded abrasive, with
    inserted nuts or washers, projecting studs, or
    tapped plate holes on one side of the disk. The
    side is mounted on the faceplate of a grinding
    machine.
  • Only the exposed flat side is designed for
    grinding.
  • Inspecting abrasive disks and wheels
  • When unpacking abrasive disks, inspect for damage
    from shipment, and have a qualified person give
    them the ring test.
  • Conduct daily inspection of grinding machines.
    Thoroughly investigate grinding wheel and disk
    failures.

34
Abrasive Disks and Wheels (Cont.)
  • Handling abrasive disks and wheels
  • These disks require careful handling.
  • Do not drop or bump them.
  • Do not roll large disks and wheels on the floor.
  • Transport disks and wheels too large or heavy to
    be manually carried by hand truck or other means
    that provide support.
  • Storing abrasive disks and wheels
  • Store them in a dry area not subject to extreme
    temperature changes, especially below-freezing
    temperatures.
  • Breakage can occur.
  • Store them in racks in a central storage area
    under the control of a specially trained person
  • The storage area should be as close as possible
    to the grinding operations to minimize handling
    and transportation.
  • Follow manufacturer recommendations for storage
    length.

35
Abrasive Disks and Wheels (Cont.)
  • Mounting Wheels
  • Mount all abrasive wheels between flanges.
  • Schedule flange inspections frequently.
  • An incorrectly mounted abrasive wheel is the
    cause of much wheel breakage.
  • Before the wheel is mounted, give it the same
    inspection and ring test as it was given when
    originally received and stored.
  • Check the bushings, particularly on wheels that
    have been rebushed by the user for shifting or
    looseness.
  • Immediately after mounting the wheel and before
    turning on the power, the operator should turn
    the wheel by hand for a few revolutions. Check to
    make sure the wheel clears the hood guard and
    machine elements.

36
Abrasive Disks and Wheels (Cont.)
  • Operating a grinding machine
  • When starting a grinding machine, stand on one
    side away from the grinding wheel.
  • Allow at least 1 minute of warm-up before truing
    and grinding with the wheel.
  • Always use coolant when truing the wheel or
    during normal grinding.
  • While the machine is running, never remove a
    guard fastener or guard.
  • Do not touch any moving part of the machine or
    the rotating grinding wheel.
  • Do not attempt to manually operate a machine that
    is automatic.

37
Abrasive Disks and Wheels (Cont.)
  • Adjusting safety guards
  • The guard should enclose the wheel as completely
    as the nature of the work will permit.
  • Adjust the peripheral guard to the constantly
    decreasing diameter of the wheel with an
    adjustable tongue or similar device.
  • On machines used for cutting, grooving, slotting
    or coping stone or other materials, the safety
    guard or hood seldom offers adequate protection.
  • Safe speeds
  • Do not operate at speeds exceeding those
    recommended by the manufacturer .
  • Unmarked wheels of unusual shape, such as deep
    cuts with thin walls or backs with long drums,
    follow the manufacturers recommendations.

38
Abrasive Disks and Wheels (Cont.)
  • Work rests
  • The work rest should be substantially constructed
    and securely clamped not more than 1/8 in. from
    the wheel.
  • Check work rests position frequently .
  • Never adjust the work rest while the wheel is in
    motion.
  • Dressing abrasive wheels
  • Abrasive wheels that are not true or not in
    balance will produce poor work.
  • They can damage the machine and injure the
    operator.
  • Keep wheels in good condition.
  • Equip wheel-dressing tools with hood guards over
    the tops of the cutters.

39
Surface Grinders and Internal Grinders
  • Surface grinders and internal grinders
  • Operating requirements for surface grinders and
    internal grinders differ from those of other
    types of wheels.
  • Insecurely clamped work pieces and un-energized
    magnetic chucks are common sources of injury to
    operators.
  • If the operator takes too deep a cut or too
    quickly traverses the table or wheel too quickly,
    the wheel can overheat at the rim and crack.
  • Train operators and supervise operators to clamp
    work tightly.
  • Must control the works speed and depth.
  • Provide for some provision of exhausting the
    grinder dust.

40
Grindstones
  • Grindstones
  • When using grindstones, follow the manufacturers
    suggested running speeds and operating
    procedures.
  • Never run stones of unknown composition or
    manufacturer at more than 2,000 sfmp.
  • The size and weight of grindstones requires a
    stand that is rigidly constructed and heavy
    enough to hold the stone securely and mounted on
    a solid foundation to withstand vibration.
  • Since grindstones are run wet, take all possible
    precautions to prevent slipping accidents.
  • Carefully inspect grindstones for cracks and
    other defects.
  • Many grindstone failures result from faulty
    handling and incorrect mounting.
  • Do not leave grindstones partially submerged in
    water.
  • This causes the stone to unbalance and can break
    when used.
  • Provide an adequate exhaust system.

41
Polishing Wheels and Buffing Wheels
  • Polishing wheels and buffing wheels
  • Polishing wheels are either wood faced with
    leather or made of stitched-together disks of
    canvas or similar material.
  • Buffing wheels are made of disks of felt, linen,
    or canvas. The periphery is given a coat of
    rouge, tripoli or other mild abrasive.
  • The softness of the wheel, build up of linen,
    canvas, felt or leather, is determined by the
    size of the flanges used.
  • Do not place the wheel on the spindle with a file
    or other object held against it. This file could
    catch in the wheel and be thrown with such force
    that nearby workers are injured.

42
Polishing Wheels and Buffing Wheels
  • Mounting
  • Mount these wheels in rigid and substantially
    constructed stands that are heavy enough for the
    wheels used.
  • Speed
  • Speed range is from 3,000 to 7,000 sfpm with
    4,000 sfpm in general use for most purposes.
  • Safeguards
  • Hood guards should be designed to prevent
    operators hands or clothing from catching on
    protruding nuts or ends of spindles.
  • Exhaust hoods should be designed to capture
    particles thrown off by the wheels.
  • Never substitute a prick punch and hammer for a
    spanner wrench.
  • Operators of polishing wheels and buffing wheels
    should not wear gloves.
  • Operators should not attempt to hold small pieces
    against the wheel with bare hands.

43
Wire Brush Wheels
  • Wire brush wheels
  • Are scratch wheels used to remove burrs, scale,
    sand, and other materials.
  • These wheels are made of different protruding
    wires with different thicknesses.
  • Do not exceed the recommended speed.
  • The hood on scratch wheels should enclose the
    wheel as completely as the nature of the work
    allows.
  • PPE is especially important because the wires
    tend to break off.
  • Make it mandatory for the operators to wear
    aprons made of leather, heavy canvas, leather
    gloves, face shields, and goggles.
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