Almost all cast, forged, extruded or wrought aluminum alloys can be treated. Alloys that contain less than 5% copper and 7% silicon and do not contain lead are most suitable for the application of an HCR coating. The degree of hardness, penetration and color varies with each alloy, with the processing temperature, and with the coating thickness.
NASA tests¹ of Shuttle parts indicate that parts coated to a thickness of 51 microns (2.0 mils) "should provide superior corrosion protection for a prolonged period of time."
MAGNAPLATE HCR-F is compliant for use in "food contact involving repeated use, such as food processing equipment." ²No other surface enhancement coating can give aluminum parts 10,000 hours of salt spray corrosion resistance in food contact applications.
General Magnaplate HCR's coating thickness is consistently uniform and ranges from 0.001-0.0025" per side. Precise control of coating thickness (+-10%) permits use on close-tolerance parts such as prebalanced impellers and threaded members. By undersizing the outside diameter by two times and pitch diameter by four times (for 60 degree thread forms) of the desired coating thickness, the original thread size can be maintained after coating. for machining allowances, note that overall final thickness of the coating is influenced by two factors; A Penetration B. Growth.
The finish of the surface after MAGNAPLATE HCR application will be equal to or slightly rougher than the original surface. While not recommended, slight burnishing, lapping, or honing can be performed on a coated part, if necessary. However, removal of the surface material should be no more than 0.0002". For machining allowances, note that overall final thickness of the coating is influenced by two factors: A. Penetration B. Surface Growth
Enhanced aluminum exhibits rapid heat and cold transfer. By converting an original single flat aluminum crystal into millions of surface facets, MAGNAPLATE HCR permits heat distribution within the encapsulated outer surface that surpasses that of untreated aluminum. The proprietary polymers used in the impregnation process have a heat conductivity of 1.7 ± .03 Btu/hr/sq. ft/deg. F/in and a heat capacity of 0.25 Btu/lb/deg. F.
¹ NASA Technical Memorandum by M.D. Danford, Marshall Space Flight Center, April 1991
² FDA letter to General Magnaplate, May 22, 1987 |