Which anodes are used for hard chrome plating
The traditional anode used for hard chrome plating consists of lead alloys. The solution attacks pure lead anodes, causing excessive amounts of lead-chromate sludge to form.
Lead-tin is a typical alloy. Anodes made of lead antimony are used when the weight and length of the anode pose a problem. Anodes made of tin-lead are more durable and have a better conductivity, while anodes made of antimony-lead are stiffer. Antimony-lead anodes will not last as long and produce a lot of corrosion products. Tin-lead anodes are recommended for high-fluoride baths. When using tank anodes in high-fluoride baths they should not be hollow or ribbed, but instead solid and smooth.
Iron anodes are sometimes used in place of lead alloy anodes, especially when greater rigidity and strength is required. Iron and chromium accumulate in the bath if they are used continuously. It is best to use lead-coated iron anodes whenever possible. For special applications, such as plating very small openings with platinum wire, they can be used. However, the bath will also form chromium. Anodes for chrome plating should not contain copper, nickel or stainless steel.
In recent years, the use of niobium and titanium anodes, which are plated, has increased in hard chrome plating baths that do not contain fluoride. They have replaced the usual lead and lead alloyed anodes. This anode is made of platinized Titanium and can increase throughput by reducing plating time. Anode geometries remain constant for optimal plating results. It has a long operating life and very low maintenance.
Anodes and cathodes are typically shorter in most plating situations. This reduces the amount of excess current flowing to the work on the bottom rack. Each anode's bottom should be 6" or more above the bottom surface of the plating tank. If the part has sharp, narrow recesses such as grooves then reducing the distance between the anode and the part can help increase the thickness of deposit on the bottom of these grooves. Some parts, such as those with bosses and grooves that have sharp corners, cannot be covered uniformly unless they are coated using conforming anodes or auxiliary anos.
