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Applying Xylan - Application Techniques
Applying
Xylan - Application Techniques
The
techniques used for applying Xylan depend on the shape of the
part, the number of parts, the desired transfer efficiency, the
application rate and the type of carrier used in the Xylan formulation.
Here is a brief guide:
Spraying: By
far the most versatile and widely used technique to apply Xylan
is spraying. There are five basic types: conventional (also
known as siphon or gravity), HVLP, airless, pressure pot and
electrostatic.
-
Conventional: The
choice for small numbers of parts, where considerable manual
work is required. Almost any Xylan formulation can be applied
by this technique.
-
HVLP (High Volume, Low Pressure): A variation
that reduces air pressure and increases liquid volume. Its
greater efficiency reduces the number of Volatile Organic
Compounds released. It may not provide all the aesthetics
of conventional spraying.
-
Airless: Similar to the siphon system but
uses hydraulic pressure to move and atomize the liquid instead
of air.
-
Pressure pot: Similar to conventional spraying,
except the coating is under positive pressure. This technique
exerts more pressure than a conventional system and is recommended
for larger production runs. Almost any Xylan formulation can
be applied by this system.
-
Electrostatic: The recommended process for
very high production conditions or when an electrostatic "wrap"
is needed to coat complex shapes efficiently. Rods, wires,
outdoor furniture and other parts that require a 360-degree
coating are examples. Not all formulations lend themselves
to electrostatic spraying with conventional equipment. Some
may require isolated electrostatic systems.
Bulk techniques: These
are the most economical methods of applying coatings to small
and intricate parts such as fasteners, clips and other irregularly
shaped pieces. Transfer efficiency is exceptionally high: as
much as 95 percent of the coating is applied to parts. Bulk
coating techniques operate in two basic ways:
-
Dip/spin system: This is just what the name
implies. A basket filled with parts is immersed in a reservoir
half-filled with coating, then raised out of the coating but
still within the reservoir and spun to carry off excess fluid
by centrifugal force. Following that, the parts are cured.
Because parts are in contact with each other, which can prevent
complete coverage of the coating, at least two passes through
this process are required to ensure total coverage.
-
Barrel/tumble coating: This technique involves
tumbling parts and spraying them while hot air passes over
them. This method is preferred for extremely lightweight or
flat parts (such as washers or small O-rings) which tend to
"nest" together.
High-volume techniques:
Two are:
- Coil
coating:
Coil coating employs high speed rollers to apply precise film
thicknesses to wide, continuous sheets of metal, particularly
those that will be subsequently drawn or stamped. This process
is used very successfully for high-volume coating of cookware,
bakeware and small appliances.
-
Curtain coating: This is a high-volume application
technique in which parts are passed through a falling curtain
of the fluid material. Whitford has pioneered the development
of special coating materials that perform well under the unique
and demanding conditions of the process. With these new coatings,
curtain coating has become the fastest, most efficient, least
expensive way to coat blanks for postforming. Another advantage:
it's environmentally friendly. For more information on this
recent development, contact your Whitford representative.
Note:
Definitions of any technical terms used on this page
can be found in our
glossary.
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