Page 33 - 43260_WMC_PL_TEXT_2020-10-13_HR_Neat

plating and anodizing: POWER SUPPLIES AND RECTIFIERS

Staying Current with Power Supply

Technology Delivers a
Quality Finish

THERE ARE PLATING AND ANODIZING operations that still
run on home-made power systems. For small parts, in low
volumes, this can be a viable approach.
The problems arise when the company gets, or tries to
find, large volume orders, or needs to deliver high-quality
surface finishes. At this point, rectifiers become not just a
desirable accessory, but essential plant equipment. Being
able to maintain a steady DC current is the only way to
ensure quality results in metals coating operations.
Switching a standard AC power supply to DC is not a
difficult process on its own, but it does produce a certain
percentage of ripple voltage. Constantly measuring this
effect in the plant, to be sure it is not becoming a signif-
icant issue, is something modern rectifiers offer as a
standard feature.
The direct current essential for a successful plating
process can come from a low-voltage generator. Origi-
nally, generators were the main source of direct plating
current, but because they could be relatively expensive
to acquire and maintain, rectifiers became the preferred,
and cheaper, alternative.
A standard rectifier is made up of one or multiple diodes
that are responsible for the conversion from AC to DC.
Modern rectifiers use semiconductors to carry out the
A DC power supply from Darrah Electric.
current filtration process, and when AC is removed, direct
current will now flow through. Diodes are one of the
devices used by a rectifier to carry out the conversion. North American Rectifiers (NAR) offers its Real Time
Thyristors offer another form of control for plating rec- Ripple system as its high-end offering in this area. This,
tifiers. The usual term here is SCRs, for silicon-controlled the company says, offers users the ability to obtain the
rectifiers. Although these are also diodes, they require a actual ripple in their process in real time, right at the face
control signal at a “gate” or terminal. of the controls.
The SCR works as a regulator and a rectifier, depending The company has both air- and water-cooled systems in
on if it is used on either the primary or secondary side of its Switch Mode Rectifier range. These have controls
the rectifier transformer. The design of the SCR on any of featuring ethernet/IP, modbus, Profibus, analog/IO, and
these two sides depends on the purpose of the rectifier: various communication platforms. They can provide more
the application, the efficiency of the unit, the cost implica- than 40 diagnostic feedback messages, when used with
tion and the reliability. the standard PE 280 controller.
SCRs do have the issue of producing a direct current The company says its Power Station rectifiers and Power
that is contorted by ripple. Some larger plating rectifiers Pulse-Reverse power supplies, made by Plating Electronic,
can produce ripple that is five percent or below their “are designed precisely to meet the rising demands of elec-
rated capacity. troplating processes. Innovative technologies and impressive
To electroplate precious metals, chromium, alloys or performances, such as the digital switch mode technology
other metals, the process requires a lower ripple rate. How- offer high degree of efficiency, minimum residual ripple
ever, if the ripple is too high, a filter can be necessary to and peak control accuracy.
smooth the rectifier wave. “These features all open up new opportunities, process

www.cfcm.ca CanaDian FiniShing & CoaTingS ManuFaCTuring 33