Hard chrome plating is generally used in those applications where parts will be subjected to a very
high degree of wear and thus a thicker layer of chrome is required. The added thickness induces cracks
and greater porosity on the chrome surface. The cracks will increase with an increase in chrome
thickness. Further machining, such as grinding, polishing or honing, is necessary to improve the hard
chrome plated surface so it can be used in contact with BAL Seals. A coarse surface finish will
substantially decrease the wear resistance of the BAL Seal.
Hard chrome plating is used in approximately 95% of all applications with the remaining uses being
thin dense chrome plating (See chart No. 1 for description). Hard chrome plating is generally applied
to exterior surfaces where subsequent machining is easier.
BAL Seals operate best against a hard chrome plated surface when used with a lubricant, which
promotes a film between the plated surface and the seal surface. The lubricant can be wet, dry or a
combination of both. At low speeds under 500 ft/min (152 meters/min), pressures under 50 psi (3.2
bar), and temperatures under 70°F (21°C), wet lubricants may need to be applied on the chrome plated
surface to fill in the surface irregularities in order to reduce seal abrasion.