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 25

• HOT WORKING OF METALS

3
Hazardous Materials

• Dusts, solvents, and other materials present a
  health hazard in foundries.
• Dust is generated in many foundry processes and
  presents a twofold problem
• Cleaning to remove deposits
• Control at the point of origin to prevent further
  dispersion and accumulation
• Vacuum cleaning is the best way to remove dust in
  foundries.
• Once dust has been removed, prevent further
  accumulation by using local exhaust systems (LEV)
  that remove it at the point of origin.

4
Hazardous Materials (Cont.)

• Solvents evaluate each solvent on the basis of
  its chemical ingredients
• Proper labeling, substituting less hazardous for
  more hazardous chemicals, limiting the quantities
  in use, and using other methods of control can
  help minimize the toxic and flammable hazards
  involved in using solvents.
• Other materials many metal resins, and other
  substances present safety and health hazards

5
Hazardous Materials (Cont.)

• Other hazardous materials that are found in
  various stages and locations of hot metal
  operations include
• acrolein
• beryllium
• carbon as sea coal
• carbon monoxide (CO)
• chromium
• fluorides
• lead
• magnesium dust or chips
• manganese
• phosphorus
• resins and resin dusts
• silica
• sulfur dioxide

6
Hazardous Materials (Cont.)

• Iron-oxide fumes and dusts are created during
  melting, burning, pouring, grinding, welding, and
  machining of ferrous castings
• Use LEV to vent these fumes.

7
Medical Program

• Baseline physical examinations, including chest
  x-rays, audiometric tests, and pulmonary function
  tests
• Periodic physical examinations to detect
  incipient disease and to help reclassify workers
  as needed
• Adequate first aid facilities and employee
  training in first aid
• Observe regulatory requirements if respirators
  must be worn
• Industrial hygiene monitoring where needed

8
Medical Program (Cont.)

• Industrial hygiene equipment, such as a hand-held
  meter that detects minerals in solution, are
  extremely helpful in identifying metal
  contaminants of industrial effluents and water
  quality.
• It can measure a wide concentration range,
  meeting various international and regulatory
  standards.

9
Medical Program (Cont.)

• Ensure employees are aware of specific hazards to
  which they may be exposed and the proper control
  or emergency responses to those hazards.
• Make Safety Data Sheets (SDSs) available to all
  employees.

10
Personnel Facilities

• Encourage frequent washing with soap and water,
  and install adequate facilities.
• Coreroom workers whose hands and arms may be
  exposed to sand and core oil mixtures are
  candidates for dermatitis.
• Prolonged contact with oil, grease, acids,
  alkalis, and dirt can produce dermatitis.
• Reference industrial sanitation standards.
• Sanitary food preparation and service is
  especially important in nonferrous foundries.
• Prohibit eating in work areas.

11
Work Environment in Foundries

• Good housekeeping, ventilation, and light help
  maintain a safe and healthy work environment.
• Proper inspections, maintenance, and fire
  protection increase workers safety in foundries.
• Housekeeping
• Clean machines and equipment after each shift,
  and keep them reasonably clean during the shift.
• Place all trash in the proper trash bins.
• Keep the floors and aisles in the work area
  unobstructed.
• Properly stack and store materials.

12
Work Environment in Foundries (Cont.)

• Floor loading
• Many buildings are used for purposes for which
  they were not designed.
• Deadweight of platforms and lift trucks introduce
  floor load problems.
• Overhead cranes and hoists from wood ceiling
  joists severely taxes roof and floor members.
• Insurance engineers or local building inspectors
  can help determine safe floor load limits.

13
Work Environment in Foundries (Cont.)

• Ventilation
• Control of air contaminants is the primary
  purpose of ventilation in foundries.
• The need for ventilation may be determined by one
  of more of the following
• Federal, state, and local regulations or
  standards
• Comparison with similar operations in a like
  environment
• Collection and analysis of representative air
  samples taken by qualified personnel in the
  breathing zone of workers

14
Work Environment in Foundries (Cont.)

• Noise control
• Controlling excessive levels of noise, more than
  85dBA, may sometimes be difficult.
• Engineering is not always possible because of a
  lack of technology or is impractical.
• Develop a hearing conservation program that
  provides approved hearing protection for each
  worker.
• Minimize exposure to identified high-noise-level
  hazards.

15
Work Environment in Foundries (Cont.)

• Lighting
• Good lighting is difficult to achieve.
• Where craneways are used, light fixtures must be
  placed high and at considerable distances from
  work areas.
• Nevertheless provide good lighting for each work
  area.

16
Work Environment in Foundries (Cont.)

• Inspection and maintenance
• Follow standard inspection and maintenance
  procedures in foundries.
• Carefully select maintenance personnel.
• Train them in safe practices, especially in
  procedures for locking out controls and isolating
  other energy sources.

17
Work Environment in Foundries (Cont.)

• Fire protection
• Make periodic fire inspections.
• Perform emergency fire fighting drills.
• If a fire brigade is present, it will aid the
  safety program by keeping its members, as well as
  other employees in the foundry, safety conscious.

18
Work Environment in Foundries (Cont.)

• Facility structures
• Entrances and exitsall doors should have an
  eye-level window opening.
• Stairways provide handrails, standard
  guardrails, and toeboards for stairs having four
  or more risers.
• Floors and pits install special types of
  flooring where explosion hazards exists keep
  clean and dry.
• Galleries provide galleries with solid,
  leak-proof floors.
• Gangways and aisles should be firm enough to
  withstand daily traffic.

19
Work Environment in Foundries (Cont.)

• Compressed air hoses
• Do not use air hoses to clean clothes.
• Improper use and horseplay have caused severe
  injuries to internal organs and eardrums.
• Reduce air to less than 30 psig.
• Install whip checks at all joints.
• Prohibit blowing and brushing sand from new
  castings without regard for dust clouds produced.
• Substitute vacuum methods when possible.
• Train workers on the safe use of air hoses.

20
Materials Handling in Foundries

• General safe working recommendations
• Instruct workers in the safe methods of manual
  and mechanical materials handling.
• Provide PPE such as eye protection, safety hats,
  face shields, and gloves.
• Plan the sequence and method of handling
  materials to eliminate unnecessary handling.
• Safeguard mechanical devices and set up
  inspection procedures to ensure proper
  maintenance.
• Keep good order at storage piles and bins, and
  pile materials properly.
• Keep ground and floor surfaces level.
• Install side stakes or sideboards on tramway or
  railroad cars to prevent materials from falling
  off.
• Chock railroad cars and flag tracks.

21
Materials Handling in Foundries (Cont.)

• Sand, coal, and coke
• Prevent falls through hoppers while unloading
  bottom-dump railroad cars with fall protection.
• Be sure observers are on the scene and prepared
  to summon help in emergencies.
• Use safety ratchet wrenches for hopper doors to
  keep the doors from swinging and striking
  workers.
• Prevent hand and foot injuries by using safety
  car movers instead of ordinary pinch bars to spot
  cars by hand.
• To reduce cave-ins of loose material, prohibit
  the undermining of piles and avoid overhangs.
• Prevent electric shock by grounding portable
  belt-conveyor loaders.
• To keep dump cars under repair from being moved,
  use locking switches and car chocks.

22
Materials Handling in Foundries (Cont.)

• Ladles
• Provide a manually operated safety lock and
  suitable covers for portable ladles.
• Thoroughly dry out and heat ladles before use.
• Provide LEV to control vapors and fumes.
• Ensure that the ladle is suited for its intended
  operation and make necessary adjustments.

23
Materials Handling in Foundries (Cont.)

• Hoists and cranes
• Require preventive maintenance program.
• Gear the program to ensure that the operation is
  much safer than simply to comply with minimal
  regulations.
• Conduct inspections on a weekly basis by trained
  specialists.
• Nondestructive testing (ultrasonic) may be
  required to locate cracks and other issues.

24
Materials Handling in Foundries (Cont.)

• Conveyors
• Conveyors are used to carry sand to and from the
  mixing room.
• An endless conveyor is used to handle molds.
• When installing a system, guard shear points,
  crush points, and moving parts.
• Where conveyor systems run over passageways and
  working areas, protect employees beneath them
  with screens, grating, or guards.
• Guarding should be strong enough to resist the
  impact of the heaviest piece handled.

25
Materials Handling in Foundries (Cont.)

• Storage
• Store materials and equipment not in regular use
  in a safe, orderly manner on level and firm
  foundations.
• When removing equipment and materials from floor
  level or from storage piles, do not undermine
  piles and cause cave-ins.
• Cover bottom feeding hopper bins.
• Use racks and shelves to store patterns and
  provide keepers.
• Store flammable liquids in accordance with NFPA
  30.
• Ensure good lighting and floor conditions in
  storage areas.

26
Materials Handling in Foundries (Cont.)

• Slag disposal
• Design furnaces and pits with removable
  receptacles into which slag and kish (separated
  graphite) may flow or be dumped.
• Unless disposed of in the molten state, provide
  enough receptacles so slag can solidify before
  dumping.
• Use slag or cinder pots to decrease slag pit
  accumulation.
• The pots can be set aside for cooling and
  eliminate explosion dangers.
• Dump where there is absolutely no water or
  dampness.
• Water might cause an explosion if some slag is
  still molten.
• Before breaking up slag allow it to stand for
  several hours.

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Cupolas

• Definition Vertical cylindrical furnaces used to
  melt iron
• Charging
• Dangers are principally confined to handling
  material.
• Never unevenly load or overload barrows or
  buggies.
• Break open scrap cylinders, tanks, and drums
  before charging to prevent an explosion.
• Install railings or other safeguards underneath
  the elevators, machines, hoists, and cranes.

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Cupolas (Cont.)

• Charging floor
• Use bolted, heavy steal plates.
• Install brick flooring near the furnace to avoid
  extremely hot steel flooring.
• Observe good housekeeping.
• Construct railings from angle iron at 42 in.
  high, and 4-in. toeboards around all floor
  openings.
• Place guardrails across the charging opening.

29
Cupolas (Cont.)

• Carbon monoxide (CO)
• Is generated during some cycles in the operation.
• CO is an explosion hazard if it gets into the
  wind boxes and blast pipes.
• Supply adequate ventilation in the back of the
  cupola, and open two or more tuyeres after the
  blowers are shut down.
• Locate CO indicators around the cupola that light
  and give a loud sound.
• If CO concentration is continually above 200 ppm,
  an engineering assessment should be considered.
• OSHA 8-hour TWA is 35 ppm and the ceiling limit
  is 200ppm.

30
Cupolas (Cont.)

• Blast gates
• Blast Gates and explosion doors are successfully
  used to prevent damage from gas explosions.
• Often placed in front of tuyeres so fresh air can
  enter when the blowers are down.
• Never close them until the blast has entered the
  wind box and driven out all gas.
• Equip positive-pressure blowers with safety
  valves.
• Every cupola should have at least one safety
  tuyere, with a small channel.

31
Cupolas (Cont.)

• Tapping out
• Operators should not thrust the bott directly
  into the stream of metal.
• Dropping the cupolas bottom doors
• Place temporary supports under the bottom doors.
• One of the best methods for doing this is to use
  a block and tackle with a wire rope and chain
  leader attached to the props that support the
  doors.
• Carefully inspect beneath the cupola for water.
• Have one worker check the danger zone and warn
  nearby employees with a horn or other signal.

32
Cupola (Cont.)

• Suggested method of raising the bottom doors of
  the cupola by mechanical means.
• Only careful and experienced workers should
  repair a cupolas lining.
• A screen placed over the charging door prevents
  falling objects from dropping on workers
  repairing cupola linings.

33
Crucibles

• The principal danger in handling refractory clay
  crucibles is that one may break when full of
  molten metal.
• Have a trained inspector check all new crucibles
  for cracks, thin spots, and other flaws.
• Return to the manufacturer those showing signs of
  dampness.
• Examine the packages and the car in which they
  were shipped to find out whether or not they were
  exposed to moisture in transit.

34
Crucibles (Cont.)

• Storing
• Store in a warm dry place. Generally best in an
  oven on top of a core oven, or some other point
  where waste heat can be used
• Annealing process
• Crucibles are heated over 810 hours before use.
• Do not allow crucibles to cool before they have a
  charge.
• Moisture in walls of crucibles is quickly
  converted into steam and could become a crack or
  pinhole.

35
Crucibles (Cont.)

• Charging
• Proper care of crucibles is good economy as well
  as good safety.
• To protect the crucibles lining and structure,
  establish a process for cleaning.
• Charge them carefully, do not throw in ingots
  with such force that they bend the bottom walls
  of the crucible out of shape.
• At white heat, they are soft and easily forced
  out of shape handle with great care.

36
Crucibles (Cont.)

• Handling
• Select tongs of the proper size and shape.
• Never drive tong rings down tight with a skimmer.
• Avoid ramming the fuel bed around a crucible.
• Where possible, use a mechanical device to remove
  heavy crucibles, those exceeding 100 lbs.
• Observe safe operating practices of hoists when
  using air or electric hoists to move large
  crucibles.

37
Ovens

• Principal hazards in the construction and
  operation of core ovens and mold-drying ovens are
  excessive smoke, gas, and fumes.
• Other unsafe conditions are unprotected firing
  pits unguarded vertical sling doors or their
  counterweights, which may drop on workers and
  flashbacks from fireboxes.
• Guard firing pits.
• Install safe vertical sliding doors, wire ropes
  and chains, sturdy fastenings.
• Thoroughly inspect all sliding doors at frequent
  intervals.

38
Oven Ventilation

• Where fumes, gases, and smoke are emitted from
  drying ovens, install ducts and exhaust fans near
  the ovens doors hoods and Install the proper
  size flues to prevent flashbacks.
• Equip core ovens with explosion vents.
• Lightweight panels may be installed on top of the
  oven, or the oven may have hinged doors with
  explosion latches.
• Larger ovens should have forced-draft
  ventilation.
• Interlock the ventilation system with the gas
  supply through a time relay that allows for three
  changes of air in the oven before burners are lit.

39
Oven Inspection

• Before core ovens are lit, they must be
  thoroughly inspected.
• Only trained and qualified personnel should do
  this work.
• Establish an inspection and preventive
  maintenance program for core ovens.
• The first step of an inspection should always be
  to shut off the main valve that controls the fuel
  supply and check the pilot lights before entering
  to make sure they are off.

40
Foundry Production Equipment

• On production-line equipment, fully guard moving
  parts and other common machine hazards in
  accordance with standard practices.
• Ground electrical equipment to eliminate shock
  hazards.
• Allow repairs only on equipment that is locked in
  the OFF position and after all other sources of
  energy have been eliminated.
• Observe LOTO procedures for operations that
  require an employee to enter for cleaning or
  repairs.

41
Foundry Production Equipment (Cont.)

• Sand mills and dough mixers
• Principal danger exists when operators reach in
  for samples of sand or attempt to shovel out sand
  while the mill is running.
• In doing so, they may be caught and pulled into
  the mill.
• Guard them so that entry into either device is
  limited.
• Train employees in safe operation of both
  machines.

42
Foundry Production Equipment (Cont.)

• Sand cutters
• Throw sand and pieces of metal with bullet-like
  force.
• Guard so that efficiency of the operation is not
  reduced or give operators proper PPE if guarding
  is not feasible.
• Sifters
• Guard with enclosures or angle iron pipe
  railings.
• Place controls within reach of operators.
• Anchor portable sifters.

43
Foundry Production Equipment (Cont.)

• Molds and cores
• The principal hazards in hand molding and core
  making include letting flasks down on feet,
  pinching fingers between flasks, dropping heavy
  core boxes on feet, cutting hands on nails and
  other sharp pieces of metal in the sand, and
  stepping on nails.
• Minimize hand and foot injuries by training
  workers to handle flasks and core boxes properly
  and to wear foot protection with stout soles.
• Screening or magnetic separation to remove nails
  and other sharp metal from the sand is also
  essential.

44
Foundry Production Equipment (Cont.)

• Molds and cores
• In general molding and core making, gagger rods
  and core wires are cut, straightened, and bent
  using hammers and cutting sets, which can create
  flying pieces of metal and dirt.
• Brace heavy cores in large molds to keep the core
  from toppling over.
• Prohibit work underneath molds suspended from
  cranes.
• Vent molds properly to avoid explosions during
  pouring.

45
Foundry Production Equipment (Cont.)

• Molding machines
• Three types of molding machines are used in
  foundries straight, semi-auto, and auto.
• Equip all molding machines with two-hand controls
  for each operator.
• On automatic molding machines, install shields or
  apron-type metal guards.
• The carry-out person should stand clear of the
  squeeze at the back of the machine.
• Operators should never touch the frame while it
  is moving.

46
Foundry Production Equipment (Cont.)

• Core-blowing machines
• Straight, semiautomatic, and automatic
  core-blowing machines are used in foundries
• On semi-auto and auto machines, guard core-box
  push cylinders, counterweight cable pulleys,
  wheel guide, and table-adjusting footpads.
• Install an automatic barrier guard between the
  operator and machine.
• Equip auto and semi-auto machines with
  double-solenoid valves, and maintain the slide
  valve well.

47
Core-Blowing Machines

• To prevent sand blows, maintain parting lines in
  good condition.
• Figure 257 of a core box shows a rubber dike
  seal, which prevents sand blows and abrasion of
  the box.

48
Flasks

• Iron or steel are preferable to wood.
• Discard defective flasks immediately.
• Have competent inspectors inspect flasks at
  frequent intervals.
• Flask trunnions should have end flanges at least
  twice the diameter of the trunnions to minimize
  the danger of hooks slipping or jumping.
• Large flasks should have loop handles.
• Design trunnions and handles with a safety factor
  of at least 10.

49
Foundry Production Equipment

• Sandblast rooms Should be dust-tight and workers
  should wear air supplied respirators when working
  in them.
• Tumbling barrels Need frequent care to be kept
  dust-tight.
• Shake-out machines Present the danger of hands
  and feet being crushed or arms and legs being
  broken. Steel-toed boots are recommended.

50
Cleaning and Finishing Foundry Products

• Have qualified personnel mount and change
  abrasive grinding wheels.
• Keep required wheel guarding intact.
• Speed-test new wheels before allowing them to be
  used on the job.
• Require operators to wear full PPE for eyes,
  face, hands, and feet.
• Dust generated by abrasive wheels is a potential
  health hazard.
• Keep the space around the machines dry, clean,
  and as free as possible of castings and other
  obstructions.

51
Magnesium Grinding

• Dust-collection systems should eliminate the
  possibilities of fire and explosion.
• The dust should be wet down by a heavy spray of
  water and immediately washed into a sludge pit,
  where the dust is collected under water to reduce
  the fire hazard.
• Keep sludge pits well ventilated.
• Do not let wet magnesium dust stand and become
  partially dried.
• The collection system must have no filters or
  obstructions that allow the dust to accumulated.
• Minimize bending and turning of pipes, and clean
  them often.

52
Magnesium Grinding Dust Collection System
53
Magnesium Grinding

• General housekeeping
• Essential for the safe handling of magnesium
• Prevents accumulations of magnesium dusts on
  benches, floors, window ledges, overhead beams
  and pipes, and other equipment
• Do not use vacuums to collect the dusts, have it
  swept up and placed in a covered, plainly
  labeled, iron containers.
• Do not mix magnesium dust with regular floor
  sweepings.
• If it is not recycled back into the process,
  dispose of dust according to local, state, and
  federal regulations.

54
Magnesium Grinding (Cont.)

• Injury and fire prevention
• Start and run the grinder and exhaust system for
  a few minutes before beginning the grinding
  operation.
• Have operators of grinding equipment wear leather
  or smooth, fire-retardant clothing, not
  coarse-textured or fuzzy clothing. Brush clothing
  frequently.
• Have operators wear goggles or a full-brim helmet
  with a face shield, and gloves.
• Keep machine tools sharp and properly grounded
  for magnesium, or friction sparks may cause
  fires.
• Use neutral mineral oils and greases for cooling
  and lubrication. Animal or vegetable oils,
  acid-containing mineral oils, or oil-water
  emulsions are potentially hazardous.

55
Cleaning and Finishing Foundry Products

• Chipping
• Where castings are cleaned or chipped, provide
  tables, benches, and jigs specifically designed
  and shaped to hold the particular casting
• Install screens or partitions to protect other
  employees from flying chips.
• Install hoods and exhaust system in these areas
  to remove dust.
• Require workers to wear eye and face protection
  when cleaning or chipping castings.

56
Cleaning and Finishing Foundry Products (Cont.)

• Welding
• Considerable welding is done when cleaning or
  reclaiming castings.
• To prevent fires in welding areas, spread sand on
  the floor as it is a noncombustible and plentiful
  material, but it is also a health hazard.
• Powder washing is a method of cleaning castings
  in which a stream of powdered iron oxide is
  introduced into a gas flame to intensify the heat
  produced.
• When powder washing is used to clean or cut
  sprues, gates, and risers from alloyed castings,
  use exhaust ventilation.

57
Cleaning and Finishing Foundry Products (Cont.)

• Power presses
• Used widely in finishing departments of foundries
• Provide sufficient aisle space, good
  housekeeping, and effective lighting.
• Properly guard and maintain machines in good
  working order.
• Carefully select and train operators.
• Use mechanical feed and ejection equipment
  whenever possible.

58
Forging Hammers

• There are several types of forging hammers
• open-frame
• gravity-drop
• steam hammer
• air hammer
• Each require special safeguarding and work
  practices despite having similar hazards.

59
Open-Frame Hammers

• Constructed so the anvils assembly is separate
  from the foundation of the frame and operating
  mechanism of the hammer.
• They may be single or double frames.
• Generally use flat dies, and the work done allows
  for more machining of material.
• Open-frame hammers are used when
• the quantity of forgings to be run is too small
  to warrant the expense of impression dies.
• the forgings are too large or too irregular to be
  contained in the usual impression dies.

60
Gravity-Drop Hammers

• Drop forgings in closed-impression dies are
  produced on these hammers.
• The impact of the free falling hammers blow
  shapes the forging through one or more states to
  the finished shape.
• Forgings on gravity-drop hammers may range in
  weight from less than 1 oz to 100 lb and be made
  of any type of malleable metal.

61
Steam Hammers and Air Hammers

• Also classified as drop hammers.
• Steam or air pressure goes through a piston and
  cylinder to raise the ram and die to assist in
  striking the impact blow.
• They strike a heavier blow than a gravity-drop
  hammer using an equivalent falling weight.
• The falling weight of the ram assembly and upper
  die of double-acting steam hammers ranges from
  1,000 to approximately 50,00 lb.
• These hammers are made with many built-in safety
  features.

62
Hazards of Forging Hammers

• For the most part, all types of hammers have
  identical hazards.
• Frequent causes of injury include
• being struck by flying drift and key fragments or
  by flash or slugs
• using feeler gauges to check the guides, wear, or
  the matching of dies
• using material-handling equipment improperly,
  such as tong lifts
• having fingers, hands, or arms crushed between
  dies
• having fingers crushed between tong reins
• receiving kickbacks from tongs
• using swabs or scale-blowing pipes with short
  handles
• being burned by hot scale
• dropping stock on the feet
• noise-induced hearing loss
• foreign objects in the eye

63
Guarding

• Maintenance personnel are exposed to the
  potential danger of crushing injuries when they
  remove and install parts on the opt of the hammer
  and when they remove sow blocks, anvils, and
  columns.
• To avoid these injuries, provide and use means
  for locking out power.
• Provide safe footing for personnel by installing
  catwalks and guardrails on hammers.

64
Gravity-Drop Hammer Guarding

• Use a hand lever rather than a treadle for cold
  restrike operations.
• Provide two-hand tripping controls if
• the material being forged is not held by the
  hands or by hand tools
• a safety stop or tripping lever cannot be
  installed.
• On board-drop hammers, provide a substantial
  guard around the boards above the rolls.
• This prevents the boards form falling should they
  break or come loose.

65
Gravity-Drop Hammer Guarding (Cont.)

1. Sheet steel board guard box
2. Screen platform made from No. 9 metal
3. Steel ram safety stop that swivels on the left
   column
4. Safety chain to restrain tie bold and nut
5. Catwalk and belt catcher

66
Steam and Air Hammer Guarding

• Should have a stop valve or quick-opening and
  quick-closing valve.
• Provide a safety head in the form of a steam or
  air cushion to prevent the piston from striking
  the top of its cylinder.
• Connect the cylinder heads and safety heads
  bolts to an anchored wire rope.
• If the hammer has no self-draining arrangement,
  install a drain cock.
• If air or steam is used to remove scale, provide
  a quick shutoff valve so that the pressure can be
  regulated.

67
Key-Driving Rams

• A pneumatic key-driving ram is superior to a
  manually operated one and offers a far greater
  margin of safety.

68
Scale Guards

• Scale guards confine pieces of flying scale,
  install them as standard equipment on the back of
  every hammer.

69
Guarding

• Treadles and pedals
• Provide treadles and pedals with ample clearance.
• Guard them to prevent them from being
  unintentionally tripped by a falling object.
• Guard any portion at the rear of the hammer so
  scrap material cannot interfere.
• Use interlocks on treadles.

70
Guarding (Cont.)

• Flywheels and pulleys
• Enclose with a guard that is strong enough to
  prevent the pulley from falling to the floor
  should the shaft break.
• In some instances, the guard enclosure is
  supported from the floor by an I-beam.
• Restrain all cylinder bolts, gland bolts, and
  guide bolts and liners, as well as the head
  assembly over the operators working position.

71
Guarding (Cont.)

• Safety ropes keep the cylinder head, tie plate
  bolts, and gland bolts from falling if they
  break.
• The tie plate bolts and gland bolts are secured
  to the master rope.
• The gland bolt safety rope should be tight enough
  to prevent a broken gland bolt from swinging down
  and striking the ram.

72
Safety Props

• Provide safety props equipped with handles at the
  middle.
• Require workers to use them when repairing,
  adjusting, or changing dies.
• The props should be held in place while power is
  released this permits the weight of the upper
  die and the ram to rest on the props.
• Operators should never place their hands on top
  of a prop.
• Ram props should be made of steel, magnesium, or
  aluminum.

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Die Keys

• Never use mushroomed keys keys should be tapered
  for clearance.
• Keys must be the correct length.
• If keys project farther, they become a hazard to
  the operator working in front.
• They may also break off while the hammer is
  operating and fall between the dies in back.
• Stock an adequate supply of die keys so drifts
  will be needed only when the end of a key becomes
  distorted and must be cut off before the key can
  be driven out.

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Design of Dies

• Usually made of chrome, nickel, of molybdenum
  stellite due to high heat, shock, and abrasion
  resistance.
• Selection of the proper die steel in the correct
  range of hardness is important in controlling
  checking and breakage.
• Size, amount of striking surface, and height are
  other factors in the safe design of dies.
• The dies must be made so they meet in precise
  alignment.
• Frequent inspection is necessary.
• Avoid welding to correct defects or to maintain
  specifications.

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Setup and Removal of Dies

• When forge dies are set up or removed, the hammer
  operator should act as leader of the group.
• The operator should see that all efforts are
  coordinated and that all safety rules are
  observed.
• Pre-setup activities
• Clean around the hammer.
• Do not perform maintenance work on the equipment
  when setting up a die.
• Ensure good lighting and flooring.

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Setup and Removal of Dies (Cont.)

• Setup
• Prop the ram securely and shut off and lockout
  the power.
• Drive die dowels into the dowel holes in the die
  shank.
• After the bottom die of a steam hammer has been
  set in place, drive the bottom key to help line
  up the die and partially tighten it.
• Invert the top die and set it in position so the
  dies are face to face with the match lines
  aligned. (Reverse this procedure for a
  gravity-drop hammer set and key the top die
  first.)
• Remove the safety prop between the ram and sow
  block.
• Let the ram descend slowly until it engages the
  die.

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Setup and Removal of Dies (Cont.)

• Removing dies
• Clear the area around the hammer.
• Shutoff and lock out the hammers energy sources.
• Use a special type of adjustable knockout that is
  held in position mechanically rather than
  manually.
• After die keys have been driven out, raise the
  ram and prop it at once.
• After removing the dies from the hammer, extract
  the dowels.
• Load the removed dies onto low, steel pallets and
  take them from the area as soon as possible.

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Setup and Removal of Dies (Cont.)

• Adjustable knockout key

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Forging Upsetters

• This is a horizontal machine that forges hot bar
  stock, usually round, into many forms via
  squeezing action.
• Enclose the machine as much as possible, except
  for the feed area.
• For safe operating conditions, keep the area
  around the machine clean and clear of
  obstructions and litter.
• Use lockout procedures before attempting to make
  any changes to dies, heading tools, stock gauges,
  or backstops.

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Nondestructive Testing

• Visual observation cannot locate all small,
  below-the-surface defects in casts and forged
  metals without damaging the parts being tested.
• Proper nondestructive testing reveals defects
  inherent in metals and other solid materials or
  those that result from processing or in-service
  use.

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Nondestructive Testing (Cont.)

• The types of testing most commonly used for
  forged and cast metals are the following
• magnetic particle inspection
• penetrant inspection
• ultrasonic methods
• triboelectric method
• electromagnetic tests
• radiography