Mechanical Plating is a Simple, Reliable Process
The
mechanical plating process,
according to PS&T's
recommendations,
is conducted as follows:
1. Parts are usually cleaned in a hot
alkaline soak cleaner,
then dipped
in an acid pickle, then rinsed.
2. Clean parts which are
free from oil and scale are loaded to
a
rubber-or plastic-lined plating
barrel, usually
hexagonal in shape.
Plating barrels may have capacities
as low
as 1.5 cubic feet
of parts and as high
as 30 cubic feet.
3. Parts
can also
be cleaned
in the
barrel using
one of PS&T's Descaler/ Degreasers
specifically designed
for cleaning
parts in the
barrel prior to mechanical
plating. Some parts may
be plated
without cleaning, using the cleaning
capability of the PS&T
Starter chemistry to clean the parts.
4. With the parts,
impact media is loaded to the barrel. Impact
media is a mixture of varying sizes of spherical glass beads ranging
from 4 mesh up to 60 mesh.
Normally equal
quantities by
volume of glass beads and
parts are loaded
to the barrel, although
heavier parts or heavier coatings of more difficult
parts require
a higher media-to-parts
ratio.
5. The water level in the barrel is then adjusted
to an appropriate level for the parts to
be plated.
For most parts,
the water level
should be approximately 1 to
2 inches ahead
of the media/parts/water mix when the barrel is rotating
at the proper
speed.
6. The temperature
of the media/parts/water mix
should be 700F.to800F., although PS&T's
processes will
operate somewhat outside
this range.
Lower temperatures
result in slower
plating; higher
temperatures will result in more rapid plating.
7. Next, Starter
is added
to provide the correct chemical environment for the plating process. PS&T manufactures a variety of
different Starters as well as Starter Concentrates, which are used with separate
acid sources.
8. The barrel is
allowed to rotate
for approximately two minutes,
allowing the complete distribution of the Starter into the mix.
9. Next,
a proprietary
coppering formula
is added
to the barrel.
In combination with the Starter,
this formula produces
a tightly adherent copper colored
coating on the
parts,
providing a uniform,
predictable base for subsequent
mechanical plating.
PS&T manufactures a
variety of coppering formulas. Usually
this step requires from
4 to 8 minutes.
10. Once the
coppering step has been completed, a proprietary Promoter chemical is added
(PS&T makes
a variety of
Promoters for specific applications).
This compound promotes the plating of the mechanical plating metal.
11. Next, a
small quantity
of metal is
added to the barrel
to produce a 'flash' coating
that provides a
sound base
or the subsequent
addition of plating metal.
12. Once the parts have achieved a silvery hue,
plating
metal is added to the barrel in
an appropriate quantity
for the surface area
of parts in
the barrel and the thickness
of coating desired.
Plating metal is extremely fine dust, 3
to 20 microns
in diameter; the much
larger size of the impact media 'cold welds'
the
metal plating powder to the parts. PS&T chemistry provides the correct chemical
environment for
this mechanical plating
process to occur.
13. Normally, the
metal to be
plated is split
into a number
of separate additions. Increasing
the number of separate additions provides a
more uniform coating
and reduces the part-to-part variation.
14. pH is
monitored carefully by the plating
operator during the process. The pH is
not allowed to rise above a value
of 2.0, since plating ceases above that value.
15. Once
all of the metal additions have been made,
the operator checks the coating thickness. It
is important at
this point to
plate out the metal powder remaining
in the barrel, providing for
a more tightly
consolidated coating and more efficient
utilization of the plating metal.
16. Once the
parts have achieved
the target plating
thickness, they are rinsed and Separated from the plating media.
17. After the
parts are rinsed, they
may be treated
with a conventional yellow, olive drab, or
clear chromate or with PS&T Brand
Hyperguard, a no-rinse clear
chromate.
18. Following
the optional
application of
chromates, Hyperseal may be applied to
the surface of the
parts. This
can significantly extend
the corrosion protection
of the coating system.
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& Technologies. All Rights Reserved.
317 N. Mechanic Street, Jackson, MI 49201
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