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Sheet Basics / Hot
Dipped Process
Hot-Dip Coating Process
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Hot-
Dip Coating Line
This is a view of the entry end of a hot-dip
galvanized/GALVALUME® line.
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The line is big and about a quarter
of a mile long |
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The cold-rolled coils are staged
ahead of the line |
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These cold-rolled coils are welded
end to end and proceed through various processing
steps, all determined by the customers'
specifications. On the other end of the line, the
galvanized or GALVALUME® Coated Sheet is recoiled, tested,
packaged and shipped. |
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Cold-Rolled
Coil
This is a close-up of a cold-rolled coil being charged
into the hot-dip coating line.
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Cleaning
Section
The cold-rolled or hot-rolled and pickled strip
(depending on ordered thickness) enters the coating line,
and all rolling solutions, lubricants and other surface
contaminates must be removed to ensure metallic coating
adherence and proper surface quality. The strip moves
through a series of heated caustic solutions and is
rinsed prior to entry into the continuous annealing
furnace. |
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Annealing
Furnace
This is the horizontal annealing furnace, where the strip
cleaning process is completed and the strip is
continuously heat treated to achieve the specified
mechanical properties. The extent to which the fast-
moving strip is heated depends upon the ordered
specification and end-use processing requirements.
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Air
Knives
The air knives control the thickness of the metallic coating through a closed loop
process between a coating thickness measuring instrument, a process computer and
the air knives. The measuring instrument determines the metallic coating thickness. The
process computer compares that to the order specification and adjusts the airflow
through the air knives in relationship to the specification and the speed of the
strip through the knives. The high-velocity air flow strips the excess zinc or
aluminum/zinc from the strip to achieve the desired coating thickness. |
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Temper
Mill/Tension Leveler
Depending upon the ordered specification and application, the temper mill may be used
to smooth the metallic coating surface. Prepainted galvanized or GALVALUME® Coated Sheet generally
undergoes temper mill rolling.
The tension leveler stretches the strip beyond its yield point in order to improve the
strip's flatness. This can be beneficial to many product applications.
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Roll
Coater
The roll coater applies a very thin coating of acrylic to both sides of the metallic-
coated strip in the production of ACRYLUME® Coated Sheet and ACRYZINC® Coated Sheet. This process is
carefully controlled to achieve uniform acrylic coating coverage and thickness.
Following the acrylic application, the strip passes through a drying furnace to
achieve proper curing of the acrylic coating.
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Coating
Line Exit End
At this point, the finished galvanized or GALVALUME® Coated Sheet
is recoiled, tested, packaged and prepared for
shipment to our customer or outside processor for a
variety of processes which might include painting,
slitting, cutting to length and much more.
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