Purpose Of Plating
Chrome plating is the process by which chromium ions dissolved in water are electrochemically transformed into chromium metal atoms and deposited uniformly across a conductive metal surface. There are two general types of chrome plating: hard and decorative. Hard chrome plating applies a thicker, dull layer of chromium metal on top of industrial parts such as hydraulic cylinders, gun bores and rollers. These parts are made of hardened steel which, despite its strength, is poor at oil retention and other wear-resistant properties. Adding a layer of oil-retaining chromium solves these problems.
Decorative chrome plating is the type consumers are probably more familiar with: brilliant, smooth and highly-reflective
Why Hard Chrome Plating ?
Chromium is a hard metal with a fine grain structure. This makes it ideal for protecting the engraved copper deposits applied to metals During press runs of any length hard chromium protects the metals from wear caused by paper and grit abrasion and, under normal conditions, enables the metals to print in clearer, sharper lines for the entire run.
Chromium plated metals also have greater corrosion resistance which protects the metal during storage and permits it to be put back into service quickly with minimum of preparation. Without the abrasion protection of hard chromium, metals wear quickly and the printing soon becomes distorted. Properly applied chromium deposits protect the engraving and extend its reproduction fidelity through several press runs.
This is possible because the normally poor micro throwing power of chromium plating baths enables them to reproduce the copper substrate surface exactly. Thus the engraving lines and patterns remain sharp and clear. This differs from plating solutions with good micro throwing power, such as bright nickel, which would tend to fill in the engraved lines. For this reason, special care must be taken to polish metals before hard chromium plating since the chromium bath will also reproduce any undesirable surface imperfections in the copper plating such as nicks and scratches.
