Canadian Finishing & Coatings Manufacturing - Sept/Oct '23 - 37

PLATING AND ANODIZING: PRETREATMENT
When thinking about your cleaning stage, there are some elements
that you can control and toggle as needed. The acronym " WATCH "
stands for Water, Action, Time, Chemical, and Heat.
can run at a lower temperature or for less time. If temperature is your limiting factor,
you may need to increase concentration or temperature.
Immersion Cleaning Tank
Cleaning aluminum alloys
prior to plating requires different
pretreatment steps compared to
steel and other alloys. This is due
to aluminum's high affinity for
oxygen. A typical cycle consists of a
non-etch alkaline cleaner, alkaline
or acid etch, deoxidizer and zincate
(immersion zinc plate). Depending
on the alloy of aluminum, the etch
step may be omitted. There are a
range of chemicals and proprietary
blends available for the deoxidizer
which also depend on the alloy
being processed. Often a double
zincate cycle is used where the
first zincate coating is removed in
a nitric acid solution and a second,
thinner zincate coating is applied.
One of the challenges in particular
for job shops that process a wide
variety of aluminum alloys is being
able to alter their process as needed
for proper pretreatment.
cleaning
When thinking about your
there
stage,
are some
elements that you can control and
toggle as needed. The acronym
" WATCH " stands for Water,
Action, Time, Chemical, and Heat.
The lower the conductivity of your
water the better as some of the ions
and contaminants in harder water
can interfere with the cleaning
process. Action refers to how the
chemistry is being applied on parts
i.e. what is the pressure of your
sprays or flow over the parts in
an immersion application. Time,
Chemical, and Heat are all factors
where your change in one area can
affect the parameters needed in
another. If you are short on cycle
times, you may need to increase
the heat or the concentration of
your chemistry. If you are running
a higher concentration, maybe you
Many cleaning chemistries have been used for decades per the old mantra " if
it isn't broke, don't fix it, " but increasing pressures from environmental bodies and
customer preferences seem to be dictating some changes. Sustainability is no longer a
differentiator but is becoming a demand of many platers. Low temperature cleaners
are being developed and trialed to help reduce a plater's footprint and spending.
Nonylphenols that were once a standard of cleaning chemistries are being more
aggressively regulated and their phase out of formulations is being accelerated. Platers
are also experiencing staffing shortages and are requesting fully formulated products
where in the past, they may have wanted to split out some of the commodities as tank
side additives to save cost.
Properly preparing your parts is key for any quality plating operation. Trying to cut
corners or save a few dollars could prove to be very costly in part failures and defects.
Take time to work with your chemical supplier to find a solution that works for your
line, your parts, and you.
Max George is a Senior Product Line Manager at DuBois Chemicals and has over 11
years of experience in the Surface Finishing Industry.
EVERY CHALLENGE
IS DIFFERENT.
And so are our
finishing solutions.
Fabtech, Chicago
September 11-14, Lakeside Center
booth # D 40108
nutroinc.com
For e.g. metal and
rotational parts
venjakob-na.com
September/October 2023
37
http://www.nutroinc.com http://www.venjakob-na.com
Canadian Finishing & Coatings Manufacturing - Sept/Oct '23

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