Forging
Steel bar is forged into cups,
cones, wear rings, and automotive rings in hot forging. Steel bar is fed through an induction
heater system until it reaches a temperature near melting. This temperature offers maximum formability
for hot forging. The
heated bar is sheared into slugs once it reaches the forging
press. Then the slug is upset, partially formed, and pierced. The
main forging press produces about 8 parts per minute. Smaller
forgings are rolled into larger rings in open die ring
rolling where the part is worked between a king wheel and
mandrel. Ring rolling imparts directionality
to the grain structure that goes with the shape of the part. This increases the application strength
and fatigue life of the part.
After ring
rolling, the part is further sized on diameter to bring it
closer to near net shape. The forging then is placed on the draw
line which offers several options for cooling: air, controlled
temperature, etc.
Cold Forming
Multi-station transfer presses are used to form seal cases and cages from sheet
steel . This press produces over 600 parts per minute for seal cages and
over 850 parts per hour for seal cases. The as stamped seal cases are phosphated
and chemlocked in preparation for molding. Cages
are wheelabrated and then phosphated.
Cage components are subjected
to a deburring
process to remove sharp edges and loose material as well
as to relieve surface tension. The
wheelabrator shown uses peas-sized shot to bombard the surface
of the component. After deburring the cages are phosphated,
then closed as part of a unitized assembly with the cone
and rollers.
Roller pre-forms are drawn and
stamped from steel coil using a cold header. A draw line straightens and reduces the
coil before it is fed into the header. The
header shears a length of the bar and forces it into a tapered
die forming the head and body. One
cold header can produce 3,000 rollers per hour.
Seal Production
Unique rubber compounds are produced at Brenco for seal production. The
rubber is compression molded onto the seal cases using vacuum presses. The rubber compound is mixed
until compound is completely dispersed, then it’s rolled into a "pig" and
loaded into a hydraulic extruder. The
extruder forms the rubber compound into a pre-form of specific size and weight. In
the vulcanizing or molding operation. The
seal casing and the compound pre-form are mated together in the mold cavities
during the vulcanization process. Vacuum
presses control hydraulic pressure, platen position, and platen pressure to
control seal curing. A vacuum storage reservoir is required to evacuate the
press cavities during the vulcanizing process. Using
a vacuum allows for a more consistent, defect free operation. After the molding operation, the outside
diameter of the seal casing is coated with an adhesive gasket material. This ensures a good seal between
the seal casing and the cup counterbore. The seal is pre-lubricated with grease
between the Dust Lip and Fluid lip.
Machining
As forged components (cups, cones,
wear rings), tubing (spacer, wear rings), and castings (backing
rings, end caps) are all machined on multi-spindle chuckers,
single spindle CNC lathes, and unique CNC equipment. Near
net forging of raceways components (cups, cones) allows for
little machining work. Component
dimensions are consistent (often within 0.002”) for
future heat treatment. Critical dimensions are measured and
charted using an SPC process.
Heat Treat
All cups, cones, rollers, and wear rings are heat treated prior to grinding
to provide the proper wear and fatigue resistance. The parts are carburized in pits by heating
them and soaking them in a carbon gas solution. Gas flow, furnace temperature,
and process time are regulated to
assure accuracy, consistency and maximum efficiency of the operation. After case carburizing, the parts are
cooled to room temperature, heated in a rotary furnace, oil quenched and
drawn to provide a case-hardened part with controlled dimensions. The Metallurgy lab verifies heat treat
case depth, hardness, carbon content and grain structure and retained austenite. Rotary tray furnaces were installed
to heat treat high volume components as part of project renewal. Pusher
tray furnaces offer consistent environments for carburization, cool down,
reheat, quench, and tempering of a continual product flow. The
system has proven to be more capable, more consistent, and cost less than
the pit furnaces used at Brenco for the past 40 years. Two furnace lines are capable of handling
the high volume demands of a peak market, as the first component of a new,
lean manufacturing process.
Grinding
Finish
grinding establishes the final geometry, dimensions, and
surface finishes of the critical contact components. Face
grinding, outside diameter grinding and inside diameter grinding
are operations performed on all cups, cones and wear rings.
(Cincinnati) Roundness,
concentricity, profile and bore sizes are critical features
that are measured at the machine using statistical process
control and off-line using computerized, automatic gauges
or satellite gage labs containing measuring equipment and
knowledgeable personnel. Critical
dimensions are tracked by the ten thousandth of the inch. Rollers
are ground as part of a continuous in-line processing designed
around consistent size control from roller to roller. After grinding, rollers are visually
inspected for imperfections on the End and O.D. using computerized
automatic camera inspection systems. Eddy
Current tests are run to verify roller hardness and an ultrasonic
inspection system searches for external and internal defects
such as seams and pipe defects. At the end of
the roller lines, a fully automated machine sequentially
assembles the rollers with the cage and the cone, then transfers
the assembly to the closing press where the bars of the cage
are closed in around the rollers in order to maintain spacing. Roller
diameter variation is less than 0.0005” in each completed
cone assembly.
Inspection
Cups, cones, and wear rings receive
a calcium modified, zinc
phosphate. The
coating identifies grinding burns on raceways, services to
protect the raceways during assembly, and enhances the performance
of the raceways in service. Backing rings, cages, and seal
cases will receive rough zinc-phosphate coating to protect
from oxidation during assembly and the give the end product
a cleaner look.
Metallurgy labs are located in
each plant and service production with SPC, end of run/ start
of run verifications, as well as master certification. Brenco’s
quality team has acquired a number of certifications and
awards as a result of careful and diligent oversight of the
manufacturing process.
Assembly
Semi-automatic assembly line
is used to assemble and package the bearing according to
customer orders. An automatic, electronic, power lateral
machine measures the lateral movement of the cones and optimizes
the bearing’s bench lateral by changing the spacer
stack length. The lateraled bearing core is mated with
the requested grease seals, wear rings, backing ring and
end cap assembly prior to packaging.
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