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Mechanical plating was developed by Erith Clayton of The Tainton Co., Baltimore, Maryland, in the late 1940s and early 1950s. The Tainton Co. was involved in producing flaked metals from metal powders. In this process, metal powders were tumbled with steel balls to produce a powder comprised of thin, shiny particles. Clayton noticed that the steel balls used in the process did not rust and hypothesized that this was the result of some of the metal powders being plated onto the steel balls. Clayton felt that modifications of the chemistry could provide a process for depositing metal on metal without the use of electricity.
Clayton started a new corporation, Peen Plate, to develop the chemistry required to deposit commercial thicknesses of plating metals. After numerous experiments, a process was developed in which parts were tumbled with steel shot, zinc dust, and the chemicals that Clayton had developed. The process generally took several hours — and often took over 8 hours — to achieve the thicknesses required. The steel shot required stripping with acid after each run.
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Peen Plate, lacking the resources to achieve commercial development of the process, licensed the mechanical plating process to 3M of St. Paul, Minnesota. 3M made significant improvements in the process, reducing the cycle time to approximately 90 minutes per run. One of the most important improvements made by 3M was John Cutcliffe's development of the use of glass beads as the impact media in place of steel shot, an invention which is at the foundation of mechanical plating today. This was a useful concatenation of 3M's position in mechanical plating and their position as a leading developer of retroreflective glass beads for safety purposes (Scotchlite signs and Centerlite "Road Mix"). Glass beads have a low coefficient of friction, high crush resistance, and low abrasive wear. They are also:
• Chemically Inert
• Inexpensive
• Readily Available
• Available in Many Sizes |
• Non-Toxic
• Non-Absorbent
• Recyclable & Reusable |
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