Transcript Document

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
CHAPTER 25
HOT WORKING OF METALS
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:
1) Cleaning to remove deposits
2) Control at the point of origin to prevent further dispersion and
accumulation
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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.
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
Hazardous Materials (Cont.)
• Other hazardous materials that are found in various
stages and locations of hot metal operations include:
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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
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.
Medical Program
• Baseline physical examinations, including chest x-rays,
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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
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.
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.
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.
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.
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.
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
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.
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.
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.
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.
Work Environment in Foundries (Cont.)
• Facility structures
• Entrances and exits—all 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.
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.
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.
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
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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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Cupola (Cont.)
• Suggested method of raising the bottom doors of the
cupola by mechanical means.
• Only careful and experienced workers should repair a
cupola’s lining.
• A screen placed over the charging door prevents falling
objects from dropping on workers repairing cupola
linings.
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.
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 8–10 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.
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.
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.
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.
Oven Ventilation
• Where fumes, gases, and smoke are emitted from drying
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ovens, install ducts and exhaust fans near the ovens
door’s 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.
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.
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.
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.
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.
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.
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.
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.
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.
Core-Blowing Machines
• To prevent sand blows, maintain parting lines in good
condition.
• Figure 25–7 of a core box shows a rubber dike seal, which
prevents sand blows and abrasion of the box.
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.
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 dusttight.
• Shake-out machines: Present the danger of hands and
feet being crushed or arms and legs being broken. Steeltoed boots are recommended.
Cleaning and Finishing
Foundry Products
• Have qualified personnel mount and change abrasive
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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.
Magnesium Grinding
• Dust-collection systems should eliminate the possibilities
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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.
Magnesium Grinding
Dust Collection System
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.
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, fireretardant 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.
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.
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.
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.
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.
Open-Frame Hammers
• Constructed so the anvil’s 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.
Gravity-Drop Hammers
• Drop forgings in closed-impression dies are produced on
these hammers.
• The impact of the free falling hammer’s 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.
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.
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
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.
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.
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
Steam and Air Hammer Guarding
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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 head’s and safety head’s 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.
Key-Driving Rams
• A pneumatic key-driving ram is superior to a manually
operated one and offers a far greater margin of safety.
Scale Guards
• Scale guards confine pieces of flying scale, install them
as standard equipment on the back of every hammer.
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.
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 operator’s working position.
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.
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.
Die Keys
• Never use mushroomed keys; keys should be tapered for
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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.
Design of Dies
• Usually made of chrome, nickel, of molybdenum stellite
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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.
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.
Setup and Removal of Dies (Cont.)
Setup
1. Prop the ram securely and shut off and lockout the power.
2. Drive die dowels into the dowel holes in the die shank.
3. 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.
4. 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.)
5. Remove the safety prop between the ram and sow block.
6. Let the ram descend slowly until it engages the die.
Setup and Removal of Dies (Cont.)
• Removing dies
• Clear the area around the hammer.
• Shutoff and lock out the hammer’s 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.
Setup and Removal of Dies (Cont.)
• Adjustable knockout key
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.
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.
Nondestructive Testing (Cont.)
• The types of testing most commonly used for forged and
cast metals are the following:
1.
2.
3.
4.
5.
6.
magnetic particle inspection
penetrant inspection
ultrasonic methods
triboelectric method
electromagnetic tests
radiography