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PLATING AND ANODIZING: HEATING AND CHILLING

Metal finishing tanks with old-style gas-filled capillary assemblies solution. Although this method is less costly to install, it has some
for temperature control lack the accuracy (+/- 5 deg. F) and safety drawbacks when compared to a standard anodizing cooling system
(they can fail in closed position) now required. that operates with an external heat exchange, and thermoregula-
The temperature controller receives inputs from a temperature tion is less precisely controlled.
sensor or an RTD. The display of the digital temperature controller Cooling coils may leak, introducing refrigerant into the anodiz-
can be up to 100 ft away from the metal finishing tank, so if the con- ing vessel causing contamination and disrupting the oxidation
troller is connected to a RS-485 communication system, operators process. There is, the company says, a risk of electrolytic chemical
can control, monitor and record the temperature settings from a corrosion of immersed cooling which will drive up operating costs.
remote location. Baker Technology Associates, which specializes in rack and
Safe operation of a plating or rinse tank necessitates the instal- barrel plating systems, is another supplier that makes energy-
lation of a liquid level control. Integrating this safety device into the conserving designs its specialty. State-of-the-art controls are
digital temperature control terminal box is, Titan explains, eco- ntegral to this, the company says.
nomical as well as improving operational safety. This additional “By minimizing losses from heated tanks, and dramatically
safety device can also have an impact on insurance costs. reducing exhaust cubic feet per minute – often by more than 80
per cent – we deliver significant savings in recurring heated
make-up air and energy consumption, especially in northern US
and Canada,” Baker states. “Integral to the system’s success is
The most effective way of regulating state-of-the-art controls. For more than 20 years, we have exclu-
anodizing temperature is by using an sively utilized AUCOS control systems.”
All its control systems offer production scheduling, advanced
anodizing cooling system. Most real-time simulation, verification of layout and capacities, and op-
oxidation plants use either a water- timized concurrent processing of widely varying process recipes
and dwell times. Additionally, unlike some scheduling systems,
cooled chiller with a cooling tower or there is no need for part or fixture storage, or a queue. The controls
are available in UNIX, LINUX and Windows platforms.
an air-cooled chiller to achieve an Baker Technology Associates Inc. has its patented Platexpress
optimal anodizing temperature. System. This, the company says, provides a more consistent finish
with lower operating costs. It also offers a separate hybrid system
that uses many of the Platexpress features, but with a traditional
barrel/hoist orientation.
Cold Shot Chillers anodizing cooling systems include air-cooled The main Platexpress systems features lowered electrical
and water-cooled chillers. In explaining its technologies, the com- power consumption and thus reduced energy heating costs. It also
pany points out that “A significant amount of heat is generated dur- features lower solution drag-out.
ing an anodizing session. Generated heat must be properly dissi- “Water consumption and floorspace requirements are reduced
pated from the anodizing process to ensure even oxidization. by up to 50 percent,” Baker states. “It also reduces maintenance
“The most effective way of regulating anodizing temperature is costs, and lowers both exhaust emissions and the recurring cost of
by using an anodizing cooling system. Most oxidation plants use make-up air.
either a water-cooled chiller with a cooling tower or an air-cooled Baker additionally offers in-barrel drying. Unlike conventional,
chiller to achieve an optimal anodizing temperature.” centrifugal drying, the company states, the more delicate parts need
Cold Shot’s air-cooled and water-cooled chiller systems can be not be dumped into spin baskets for placement inside the dryers.
installed alongside the vessels containing the electrolytic fluid. A Following a final online rinse, the barrel is conveyed to semi-
fluid refrigerant is circulated through a metal finishing chiller, vacuum dryer stations featuring special, minimal rotational cycles.
which then circulates through a heat exchanger to cool the anod- Baker adds that the barrel dryers are available with automatic
ization process solution. The warmed refrigerant is sent back to the covers, to minimize energy losses.
chiller to repeat the loop. In most instances, industrial temperature control systems use
“Temperature changes within the anodizing vessel are detected well-tried methods that have been around for decades. However, as
by a thermal regulatory device installed inside it,” Cold Shot ex- the need for precision grows in today’s markets, reinforced by some
plains. “When there is an increase in the amount of heat being gen- customers’ requests for process data to ensure compliance with
erated by the anodizing process, regulatory valves in the chiller sys- specifications, demands placed on systems’ accuracy are going up.
tem are opened either automatically or manually to allow coolant In other words, off-the-shelf equipment can be used for run-
flow through the heat exchanger and cool the vessel. These valves of-the-mill manufacturing. But to remain competitive in the
are shut off when optimal temperature ranges have been restored future, a plating or anodizing firm needs to invest in up-to-date
to avoid overcooling the electrolytic process.” control systems, and perhaps also a qualified assessment of what
An alternative method of regulating anodizing temperature is its needs are likely to be in the foreseeable future. n
using cooling coils that are immersed directly into the anodizing
56 CANADIAN FINISHING & COATINGS MANUFACTURING JANUARY/FEBRUARY 2021