Introducing myself

Welcome to Finishing Talk Marc!

Curious to know if your market segment uses AC/DC alternating type of Power Supply in your hardcoating, and what you thoughts on this little known process are.  I learned a little about the Sanford Process a few years back, and have always wondered why this type of power supply is not more common in hardcoat operations.

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I thought the purpose of the AC/DC alternating type of Power Supply was either for brilliant colors in hardcoat, and/or higher operating temps - allowing for less thermal energy and higher production rates.....?

Hello,

I'm commenting on the discussion of AC/DC anodizing. As former president of Sanford Process Corporation I am familiar with the process.  Essentially, the use of AC superimposed over the DC reduces the typical buildup of resistance as the hardcoating builds. As I'm sure many of you know, typically the voltage pushing the DC has to be continuously increased to maintain steady current in the anodize bath. This is not so with AC/DC hardcoat.  Once the target current is reached the rectifier can be left alone. The process runs at low voltages (usually 15 to 18 volts) and produces considerably less heat.  The coatings are very uniform and you can accelerate process time by running at much higher current density and thereby reaching target coulumbs faster.  The rectifiers for this process are large and can cost more than a standard rectifier but they pay for themselves with increased productivity.  Used rectifiers are available in the market.

Bill Corcoran

I just emailed thekid with a response which I should have posted. There are articles and presentations that have been given at AAC and AESF and are still available.  Regarding increase in current density, it depends on load size and rectifier size but we routinely ran at 90 to 100 amps per square foot and lowered run times to 15 to 20 minutes rather than an hour.

Bill