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ANALYSIS OF METAL FINISHING BATHS
A key to Quality, Productivity, Cost-Savings and a Cleaner Environment
Browse the
resources listed on the left to see how important Analysis is in maintaining
high quality and maximising profitability in Metal Finishing operations.
WHY ANALYSE ?
Metal Finishing process baths, including electroplating solutions, electroless plating baths, conversion coating solutions, anodising baths, cleaners and degreasing solutions, not forgetting rinse baths - all perform optimally only when their chemical composition lies within set limits. Too concentrated, too dilute, incorrect pH, too high a concentration of impurities - these are just some of the parameters which must be maintained at the correct level, if the performance of a plating plant is to be optimised. If they get out of line, a Finisher could be in for an expensive ride.
IF THE BATH
IS "WRONG", THE WORK WILL PROBABLY
ALSO BE DEFECTIVE
The composition of process baths, including pretreatment and post-treatment baths, should fall within a compositional range, often specified by the process or bath Supplier. Here are some of the reasons why we should always try to maintain these baths within ‘spec.
1. Bath too concentrated
If the bath contains excessive concentrations of acids, alkalis, buffers, the main reagents (metal ions, cations), organic or inorganic additives, the consequences could be:
Defective
work. Too many rejects increase production costs. (see below)
Needless chemicals costs. The greater the concentration, the greater the rate
at which organic compounds will break down, in solution or at the anode or
cathode. Also the greater the bath concentrations, the more chemicals will
be contained in the dragged-out solution, and so lost.
Needless additional load on the effluent treatment plant, incl. chemicals used
to treat these effluents, and in some cases, payments to the Water Authority.
2. Bath too dilute
If the bath is too dilute in some or all of reagents, the possible consequences could include:
defective
work (if bath is outside supplier specification) (see below)
wasted energy. If the electrical conductivity is too low, cell voltage will
be needlessly high. Electrical energy wasted, and maybe problems with excessive
bath heating.
3. Bath contains impurities
Impurities can build up in process baths in many different ways, e.g by being carried in by the work, or liquids adhering to the work. For a fuller discussion of this, see "Defects in Metal Finishing" by David Luke and others.
The presence of impurities, anions, metallic cations, inorganic or organic species above a certain concentration, will certainly result in defective work. Sometimes these defects will be immediately obvious to the naked eye. Reworking such defective components is expensive. Other times, they won’t show up till much later – perhaps when the customer has already incorporated them in their products. Reworking these comes very expensive indeed! And often times is a good customer and a good reputation in the industry lost. It takes years to rebuild a bad reputation.
REGULAR BATH ANALYSIS IS ONE OF THE BEST INVESTMENTS A FINISHER CAN MAKE!