Accident Prevention Manual

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• 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
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CHAPTER 23

• METALWORKING MACHINERY

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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

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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

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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.

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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.
  

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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.

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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.

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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.

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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.

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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

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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.

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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.

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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.

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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

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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.

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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

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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.

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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.

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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.

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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

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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

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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

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.