In recent years, health and environmental regulations have become more stringent regarding the use of hexavalent chrome plating baths. As a result, platers are being forced to convert to tri-valent chrome baths whenever possible. Xinxiang anodes are well suited for the tri-valent plating baths as they have long life and are specifically designed to prevent the destruction of the organic additives in the plating bath chemistries.
■. Lower Metal Concentrations.
Chromium concentrations in trivalent plating baths are typically less that 1 ounce per gallon
(oz/gal). Hexavalent chromium concentrations are 15 to 40 oz/gal. Lower heavy metal concentrations mean less chrome dragout, and thus, lower waste treatment costs and less hazardous sludge generated in trivalent systems. Reducing sludge quantities also saves you money in haulage and disposal fees.
■. No Reduction Step.
By installing a trivalent system, you avoid the need to reduce hexavalent chrome wastes to their trivalent state. Since three pounds of sodium metabisulfite are required to reduce each pound of chromic acid, significant quantities of chemicals, as well as equipment and labor costs, are eliminated by switching to a trivalent system.
■. More Parts Can Be P/aced on a Rack.
Trivalent chrome chemicals produce a high quality plate even when rack densities are increased
15% above those for hexavalent chrome systems.
■. Lower Current Density.
Lighter weight, less expensive racks can be used to carry the lower currents. Simple hooks made
out of hard drawn copper wire have also worked well in trivalent systems. Use of such hooks eliminates the expense of designing and special ordering custom parts racks.
■. Fewer Rejects.
The throwing power of trivalent chrome is excellent. It is almost impossible to burn parts, too, according to satisfied shop owner, even with current densities above 100 amp/sq.ft. Trivalent systems do not experience the white washing problems that hexavalent systems do.
■. Reduced Dragout.
Tri-chrome baths are far less viscous than hexchrome. Less solution clings to the parts that are withdrawn from the bath. This reduces both treatment expenses and material costs for the makeup chemicals.
■. No Fumes.
When you stand next to a trivalent chrome plating tank, you notice an immediate difference.