Optimizing Industrial Degreasing of Brass Components for Enhanced Electroplating

The Challenge

As is well known, proper preparation is of paramount importance for the subsequent adhesion of the electroplated coating.

A client contacted us, reporting problems with their chrome-plated brass parts, which required degreasing. The chrome layer exhibited pitting, halos, and small bubbles, clear signs of inadequate preparation and poor adhesion of the deposited metal.

The parts in question came from the foundry and were subsequently machined and polished; therefore, the surfaces were contaminated with foundry sand residues, polishing pastes, and oils of various kinds.

If these residues are not perfectly removed and degreased, they cause the aforementioned defects that render the treated product unsuitable for quality control.

Our Solution

To begin, we sought to completely remove the foundry sand from the internal parts of the components, which was not being fully removed in the previous process. To this end, we added a detergent additive with wetting properties, DECADET BT/G NEWS, to the pickling solution. This additive reduces the surface tension of the pickling solution, thus increasing its wettability. This allows the acid to work more effectively and uniformly, deeply detaching the foundry sand that adhered to the surfaces of the parts during the casting process.

Subsequently, having two ultrasonic tanks with an intermediate rinse available on the electroplating line, we focused on completely removing the polishing pastes present on the surfaces, while also maximizing the degreasing power against the other contaminants used for the mechanical machining of turning and threading.

After a series of tests, we developed a cycle that involves the use of an alkaline detergent (SURFAKLIN 396M) and an acidic detergent (SURFACID RP 888). The former effectively removes almost all polishing pastes and oils without darkening or attacking the metal. The latter performs a final finishing cleaning, brightening and making the metal shiny, which, after appropriate neutralization, is ready to proceed to the subsequent electrolytic degreasing.