The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Brightening of aluminium cookware

July 10, 2014

Q. We manufacture aluminium cooking pots, and as part of the process we need to achieve a bright finish of the cookware. Our current "automatic conveyorized washing" line process is based on pressurised spray system for each section, as follows:

WORKING CYCLE (conveyor speed is about 1 meter/min)
1. Manual loading onto the conveyor
2. caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] etch at 65 °C - 3 minutes for 3 meter length of conveyor section
3. Dripping - about 1.4 min for 1.4 meter length of conveyor section
4. 1st Rinsing - about 1 min for 1 meter length of conveyor section
4. Dripping - about 1.2 min for 1.2 meter length of conveyor section
5. Neutralising with nitric acid at room temp (68% concentration) (10 parts nitric acid to 90 parts water) for 1 minute over 1 meter conveyor length.
6. Dripping - about 1.2 min for 1.2 meter length of conveyor section
7. 2nd Rinsing - about 1 min for 1 meter length of conveyor section
8. Dripping - about 1 min for 1 meter length of conveyor section
9. 3rd Rinsing - about 1 min for 1 meter length of conveyor section
10. Dripping - about 1 min for 1 meter length of conveyor section
11. Blower Drying with hot recirculated air - for 4 min to cover 4 meter conveyor length
12. Manual Offloading from conveyor

Despite the above, we are unable to obtain a shiny, bright finish of our cookware, and also the cookware is not anodized due to market requirements. All our pots/pans are come out with a dull, matte finish. The volume of cookware pieces sent thru the washing line can be anywhere between 8,000 to 10,000 pieces per 8 hours of various diameters and heights.

I would be grateful to receive any suggestions to help us improve the surface finish to make it appear shiny, bright. If there are any questions/additional info you require, please let me know.

Thanks you

Timir

TIMIR MAJITHIA
- MOMBASA, COAST, KENYA