- Email: [email protected]
Aluminum anodes for hardcoat anodizing?
I had a small polypropylene tank that I'lined with aluminum strips and used them as the cathode system. I also used a pulse rectifier and I loved the results. A very even coating. Kelly Day, Micron Tech Inc., [email protected] The use of aluminum cathodes in anodizing (Type II or Type Ill) has been proven and documented for years. Generally, use 6063-T6 or -T5, never T-52![! All welds should be made with 5356 alloy, welding rod. Anode to cathode ratio should be approximately 3:1. Charles A. Grubbs, Metalast International Inc., [email protected]
ANODE TO CATHODE DISTANCE We are using a bright nickel bath and I have a question about the setup. It is a 26-gal tank and the distance between the anodes and the cathode is 3 in. on each side. That is the way we bought the system, but someone told me the distance should be about 6 to 7 in. I cannot find any documentation on this. Please help if you have an opinion. Brian Hunt, Elliot Barry Co., [email protected] The first issue is that Ohm's Law pertains: the solution has resistance, and the farther the parts are from the anodes, the higher the required voltage will be--it's nearly a linear relationship. I have seen cases where 24 V wasn't enough. The second issue is obvious: you don't want the parts to
accidentally touch the anodes and cause a dead short. The third issue is current distribution and, consequently, thickness distribution. You would like for the distance from all points on the anode to the cathode to be the same. You haven't yet described the parts and all the fine details; but the fact is, in most cases it really isn't going to matter a whole lot whether the anodes are 3 in. away or 6 to 7 in. Ted Mooney, Finishing Technology, Kinnelon, N.J., [email protected] If it works, don't change it. If you are trying to run very irregular parts with sharp edges, further back would probably work better. Whatever the anode can "see" will plate heavier than what it cannot "see." The further back you move, the more it will tend to wrap around. The higher the current density (A/ft 2) is, the more it will tend to plate the edges. I normally use 4 in. as a minimum, but that is just a personal opinion. James Watts, James Watts Inc., [email protected] The distance is more important for baths with poor throwing power, like bright nickel, and less important for baths like zinc cyanide. Tom Pullizzi, Team*Faraday, Brighton Beach, N.J., pullizzi@ vitinc.com Ted Mooney is an independent consulting engineer based in Kinnelon, N.J. MF
)N'T LET
YOUR ROFITS GO TO
WASTE! N A P C O ' s formed Barrels are available in both PRODUCTION AND PORTABLE Styles. The ribless construction combined with the tighter perforation patterns provide much more open area allowing you to increase quantity, improve quality and greatly reduce drag out which will lessen the demand on your WASTE TREATMENT SYSTEM.
NAPCO
T h e P R O D U C T I O N B A R R E L is a v a i l a b l e with N A P C O ' s exclusive Polyglass and the Plastisol Coated Hangers in standard and fully submerged depth, PRODUCTION AND PORTABLE BARRELS can be ordered with either Titanium, Titanium Coated or Steel Coated Clamps. Call our Sales Representative at 203-589-7800 for further information.
16 North Harwinton Avenue, Terryville, CT 06786 Phone: 203-589-7800 ° Fax: 203-589-7304 Circle 061 on readerinformation card
68
METAL FINISHING . March 1997
ANODE TO CATHODE DISTANCE We are using a bright nickel bath and I have a question about the setup. It is a 26-gal tank and the distance between the anodes and the cathode is 3 in. on each side. That is the way we bought the system, but someone told me the distance should be about 6 to 7 in. I cannot find any documentation on this. Please help if you have an opinion. Brian Hunt, Elliot Barry Co., [email protected] The first issue is that Ohm's Law pertains: the solution has resistance, and the farther the parts are from the anodes, the higher the required voltage will be--it's nearly a linear relationship. I have seen cases where 24 V wasn't enough. The second issue is obvious: you don't want the parts to
accidentally touch the anodes and cause a dead short. The third issue is current distribution and, consequently, thickness distribution. You would like for the distance from all points on the anode to the cathode to be the same. You haven't yet described the parts and all the fine details; but the fact is, in most cases it really isn't going to matter a whole lot whether the anodes are 3 in. away or 6 to 7 in. Ted Mooney, Finishing Technology, Kinnelon, N.J., [email protected] If it works, don't change it. If you are trying to run very irregular parts with sharp edges, further back would probably work better. Whatever the anode can "see" will plate heavier than what it cannot "see." The further back you move, the more it will tend to wrap around. The higher the current density (A/ft 2) is, the more it will tend to plate the edges. I normally use 4 in. as a minimum, but that is just a personal opinion. James Watts, James Watts Inc., [email protected] The distance is more important for baths with poor throwing power, like bright nickel, and less important for baths like zinc cyanide. Tom Pullizzi, Team*Faraday, Brighton Beach, N.J., pullizzi@ vitinc.com Ted Mooney is an independent consulting engineer based in Kinnelon, N.J. MF
)N'T LET
YOUR ROFITS GO TO
WASTE! N A P C O ' s formed Barrels are available in both PRODUCTION AND PORTABLE Styles. The ribless construction combined with the tighter perforation patterns provide much more open area allowing you to increase quantity, improve quality and greatly reduce drag out which will lessen the demand on your WASTE TREATMENT SYSTEM.
NAPCO
T h e P R O D U C T I O N B A R R E L is a v a i l a b l e with N A P C O ' s exclusive Polyglass and the Plastisol Coated Hangers in standard and fully submerged depth, PRODUCTION AND PORTABLE BARRELS can be ordered with either Titanium, Titanium Coated or Steel Coated Clamps. Call our Sales Representative at 203-589-7800 for further information.
16 North Harwinton Avenue, Terryville, CT 06786 Phone: 203-589-7800 ° Fax: 203-589-7304 Circle 061 on readerinformation card
68
METAL FINISHING . March 1997