Summary for anodising tank overheating Discussion
Anodising tank overheating is the main problem in this thread. Suprabhat Tambe says his 20-litre lead-lined tank heats up after about 10 minutes when anodising 1.5 square feet at a time, forcing him to use ice bottles and limiting runs to 15–20 minutes. He asks what tank size is needed for 15 square feet per day, how long anodising should take, and how to chill the bath more conveniently. James Watts replies that the first step is to use a power supply that can deliver 18 or 24 volts, because 12 volts is only slightly above the rate at which the solution is dissolving the coating. He says shorter anodising time means less heat, and that the rising temperature is producing a soft anodize. For cooling, he suggests a poor-man’s system: a cheap modified freezer holding a water tank, with water pumped through 1/4-inch polyethylene tubing coiled in the anodising tank, controlled by a valve. He says additives will not solve the heat problem enough.
Q. Dear Sir,
I have an anodising tank of approximate 20 litres with lead lining. If I anodise a lot of 1.5 square feet at a time the temperature of bath rises after 10 minutes and I have to chill the solution by immersing ice bottles. This process is very difficult as I cannot control the process. Maximum time of anodising is 15-20 minutes I cannot increase this time due to heat generation.
My question to you is what is minimum tank size required for me if I am to anodise 15 square feet of job per day? Moreover how much time should be given to anodising for good results? For supply I have a DC unit which gives 12 V, 60 Amps. Max with adjustment from 6 Volts onwards with 6 Steps.
Moreover how do I chill the solution. Now I use plastic bottles but this is not convenient. Can I use Aluminium pipe used for antennas of TV. I need your help in this regard as I have come to know that you people are very helpful and you can guide me.
Thanks
Suprabhat Tambe
– Raipur, Chhattisgarh, India
September 4, 2012
A. Step one is to get a power supply that will put out 18 or 24 volts. Your anodize process at 12 volts is only a bit higher than the rate that the solution is eating the coating. Shorter anodize time = less heat.
With the temperature rising, you are getting a soft anodize. Additives will not help enough to make that practical.
A poor man’s cooling system is to get a used CHEAP freezer, modify it so it shuts off at 1 °C. Put a large metal tank in the freezer, fill it with water and pump this water thru a 1/4″ polyethylene tubing that is in the anodize tank with the return flow to the freezer tank. You need quite a bit of tubing in the tank. I would use a PVC pipe frame to keep it organized. It will take a day or two for the water to get to 1°C. The tank temps will rise.
Put a valve in the water line to control the volume of cold water and open it up more as the anodize tank temp rises.
It is a very inefficient process, but a lot better than bottles of ice water.
James Watts
– Navarre, Florida
September 10, 2012