Page 23 - CFCM Nov-Dec-2020 Final_Neat

reducing environmental impact. It is
suitable for multi-metal conversion Powder Coating Pretreatment Tips
(steel, zinc, aluminum) and can be The pretreatment process requires three steps: cleaning, rinsing, and chemical conversion
applied using dip and spray methods. of the surface.
The range includes a phosphate- Cleaning removes soils, oils, oxides, smut, and contaminants. Factors to consider
include accurate levels to improve soil removal, decrease the cleaning time and provide an
free, liquid pre-treatment based on
optimum surface for the phosphate layer. Titration readings measure the total alkalinity or
trivalent chromium and zirconium for
acidity levels. Increased temperatures will improve the action of the detergent and allow for
the treatment of steel, galvanized steel
less time in the cleaning process. Sludge or soil build up in tanks should be monitored as it
and aluminum surfaces; and an inno-
will reduce the cleaning activity even with good titration readings.
vative liquid cleaner / coater designed Rinsing removes any remaining contaminated solutions from the surface while diluting
for ferrous material, aluminum, zinc the chemicals to stop their action. It also adjusts the pH for the next step.
and alloys, which creates a strongly Chemical Conversion of the surface commonly includes iron phosphate for ferrous
adhering, zirconium-based conversion metals, zinc phosphate for ferrous metals, chromate conversion for aluminum, or
layer for various types of paint. manganese phosphate.
The process is fast and can be done Conversion coatings are a complete film which changes the physical and chemical
at room temperature, Bonderite says. nature of the metal surface. These coatings deposition weights are measured in milligrams
and are grey to blue iridescence or blue to gold iridescence. A clean surface is required for
No matter how you slice it, clean
the reaction.
workpieces are essential to the success
Seal with a neutralizer to stabilize the conversion coating. The temperature of the rinse
of downstream processes such as paint
increases the solubility of the residues and improves dry time. Proper flow patterns and rinse
or powder coating, and form the foun-
volume promote a more thorough rinse. Overflows and screens are used for the removal of
dation for high-quality coating. An the soils, oils, and other contaminants.
optimal process can be achieved by
adjusting a few parameters individual TCI Powder
to each business. n

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