The key to Metal Finishing is all in the Pre – Treatment! I know it is an Industry cliché, but you give yourself the best chance at producing good parts if you have a good (maintained) pre – treatment cycle, that fits your needs specifically.
Every shop, every process, is different in their own way. These differences are determined by location (water quality, atmospheric conditions), types of parts (base metal, configuration, manufacturing), equipment, and their industrial applications. Your Pre – Treatment Cycle should be designed and based on these differences.
That being said, once these variables have been addressed, you must stay on top of the maintenance of the Pre – Treatment process to insure that your parts are clean and ready for their final finish. Maintain the recommended concentrations at all times. Keep your temperatures 5 – 10 degrees above the suggested setting for your cleaners (large loads will drop the temperature upon entry) Be sure that your current in your electro – cleaner (if you are using) is ample enough for the part your finishing. A good rule of thumb is 2 - 3 x the asf for the plating bath. Make sure your emmersion times are adequate so your cleaners can do their jobs. Dump the solutions when you see that they are spent. If you have oil floating on the surface, that usually is a good indicator that the cleaners are saturated and need to be dumped and made up fresh. (unless the cleaners are designed to float oil)
The acid pickles need to be fresh and strong, so check them regularly. If you see little reaction with the base metal upon entry, they could be spent, even if the concentration indicates otherwise. So, consider all factors when doing your analysis.
Lastly, make sure the rinsing is maintained in the Pre – Treatment Cycle. Keep them clean so you do not neutralize the pHs or contaminate the tanks down line with oil drag out.
My philosophy is keep it simple. When in doubt, dump it, make it strong, and keep it hot! If you do these things, you give yourself a good start to a good part!
Please feel free to contact me if you need some help. Have a great 2013 and make sure it is bright and leveled!