Metal Finishing Guide Book


Issue link:

Contents of this Issue


Page 100 of 843

of surface cleanliness is required. Part configuration, drain vestibules, and adequate time are important considerations in reducing overall water usage. Table II shows typical cleaner dragout that can be expected from various part configurations. Many improvements in rinse stages have been tested and employed to reduce the volumes of effluent to be treated. A common practice is the backflow rinses in a conventional five or more stage pretreatment system. The process is as follows: 1. Clean 2. Rinse 3. Phosphate 4. Rinse 5. Seal Finishing system organizations have introduced unique design improvements to utilize rinsewater more efficiently and to assist in maintaining rinse cleanliness. Counterflow rinsing provides the cleanest possible water as the last contact with the part, and allows for multiple use rinse effectiveness. The major control mechanisms for rinse tanks remain the control of pH and total dissolved solids (TDS). These tools have been automatically incorporated into washers, which allow sensing devices to either increase the overflow rate or reduce or drop TDS by automatic draining, thus maintaining consistency in water quality without regard to part shape, drag-in or drag-out. 97

Articles in this issue

view archives of Metal Finishing Guide Book - 2013