Bright Nickel plating has been used in nearly every area of manufacturing. Whether it is plumbing, automotive, food service, military, machine and equipment components, or fasteners bright nickel provides an aesthetic finish with good corrosion resistance. Bright nickel electroplating processes may be in coil / sheet lines, reel to reel, barrel or rack processes. For this discussion we will consider the rack and barrel processes. Bright nickel typically serves as a bright finish to provide a cosmetically pleasing finish over steel, brass, or copper. Usually it is a decorative under layer for “bright gold”, “bright silver”, and bright chrome. Bright nickel provides depth of finish therefore enhancing the cosmetic appeal.
Just as there are different, end use, applications there are also different proprietary processes to achieve the desired results. When looking at the processes available it is important that this is not a “one size fits all” scenario. You as the finisher have to know your process inside and out as well as what the finish requirements are.
Proprietary bright nickel processes are basically divided into two systems, one is a “leveler” system and the other is an “index” system. Leveler systems are typically based on pyridine or pyridine type additives whereas index systems are based on a sodium allyl sulfonate chemistries. Other additives are used to enhance the brightness characteristics and ductility but that is the basic distinction.
Index Systems have been around forever and have continued to evolve as new organic additives are made available that work in conjunction with the SAS products. They produce very good bright work and have broad range application for both barrel and rack. The deposit stress, when ran correctly, is lower tensile stress. It provides very good post process receptivity especially with chromium. Current densities are typically limited to 45 ASF or lower to produce a bright, level, low stress deposit. The flexibility of the index process makes it a true workhorse and is widely accepted in industry sectors where deposit stress is of greater concern.
Leveler systems, the pyridine family of processes has also evolved. Early movement into this process type produced problems for some due to the high level of brightness and deposit stress. Later generations of Leveler processes have used newer organics in concert with the system to greatly improve the use and performance of the products overall. Leveler systems provide a very high level of deposit brightness over a broad range of current densities but the best use in current densities ranging from 30 ASF and higher lower current densities may show lack of leveling or uneven brightness sometimes making it more challenging to use in barrel plating applications. Often times to overcome uneven or dull low current deposits, additional brightener is added but flaking may result. Other additives are available that will enhance this LCD without flaking.
Both processes Index and Leveler are good. Make sure to know the parameters and requirements of the product to be plated. Know the operating ranges of your system prior to installing or converting. The chemical supplier should be able to recommend the right process for the right application and help tailor the process to meet the application needs.