METAL FINISHING EQUIPMENT

CHEMICAL SOLUTIONS

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Acid Pickle  

The primary function of an acid pickle is to remove surface oxides such as rust and carbon scale, such as heat treat scale and weld scale. Once the metal surface is free of all oxides, the acid activates the metal surface to make it receptive to subsequent operations; plating, black oxide, etc.  All oil must be removed from the surface of the parts prior to entering the acid pickle. If oil remains on the parts or if it is drug in from previous process baths, it will float on the surface of the acid solution and redeposit on the parts as they are removed from the pickle. In many process lines, an acid additive can be used to help emulsify residual oils, assist in the carbon scale removal and provide inhibition which reduces the acidic attack on the metallic surface.  If steel is removed from an acid pickle and exposed to the air for an extended period of time, it will begin to flash rust.  If parts begin to oxidize or rust prior to entering a plating or chemical finishing process bath, the deposit characteristics will be compromised and the parts will likely be rejected.  

Acid pickling can be accomplished using a variety of acids or combinations of acids,as well as a blend of acid salts.  There are numerous formulations of acid salts and each are formulated to address and the surface condition and base metal being processed.  Care must always be taken to select the acid formulation that best suits the substrate, the process line and the operating facility.   

For many applications, including zinc plating of springs and other critical automotive components, an inhibitor is used in the acid to prevent over pickling and to minimize the infusion of hydrogen into the metal.  Some acid inhibitors  will improve carbon scale removal, emulsify oils and extend the life of the acid pickle process bath.    

A JSA Technical Sales & Service Representative can audit yourprocess and recommend the best options to improve your production.  Please contact JSA for ways to improve the performance and extend the life of your acid pickle.  

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