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Measuring the etching time in HF HNO3 prior to Anodising

Hi

I work for a titanium fastener manufacturer, we have an automated anodising line and would like to control the etching time to 5-20 secs after gassing has commenced as called for in ISO8080. The problem is that travel time from exiting the etching tank to complete immersion in the rinse tank takes 39 secs (that includes 15 secs draining). At what point is etching time measured, am I correct that it starts from exiting the etching tank to complete immersion in the rinse tank, or, is it from start to finish exiting the etch tank. I would be grateful for further tips on controlling the etching times on an automated line.

Many thanks

Mark Mat
Fastener Manufacturer - Midlands , UK
October 22, 2009

adv.