Metal Finishing Guide Book

2011-2012 Surface Finishing Guidebook

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Page 346 of 707

Only occasionally is the part heated to approximately 130 oF, and never does the temperature of the part exceed 212 oF. Hence, distortion of the part does not occur. • The process can be used on most metals and alloys. Excellent adhesion is obtained on all of the commonly used metals including steel, cast iron, aluminum, copper, nickel & nickel alloys, stainless steels,zinc, chromium and titanium. • Thickness of the plated deposit can be closely controlled. Frequently, mismachined parts can be plated to size without remachining. • Parts having a wide variety of sizes and shapes can be easily brush plated. Some disadvantages of brush plating compared to other repair processes are: • Brush plated deposits are applied at a rate that is at least 10 times faster than tank plating. However the rate of deposition is considered to be moderate when compared to welding or metal spraying. A fair comparison is not complete unless consideration is given to the quality of a brush plated deposit and the fact that brush plating often eliminates the need for pre or post machining and grinding, which is required with other repair processes. Because parts often can be plated to size, brush plating provides a finished product in a shorter period of time. • In practice, the hardest deposit that can be applied in a high thickness with the brush plating process is 54 Rc. This is not as hard as the hardest deposits produced by some other processes. However, the other processes do not offer the range of hardnesses or deposit types that can be applied with the brush plating process. • Brush plating is usually a superior approach to plating a selected area on a complex part. However, it usually is not suitable for plating an entire part that has a complex shape, such as a coffee pot. QUALITY OF BRUSH PLATED DEPOSITS Brush plated deposits meet the performance requirements of their tank plated counterparts. Manufacturers of brush plating products are continuously improv- ing their solutions and well as developing new solutions, procedures, and equipment to meet today's demanding applications. Some examples include the develop- ment of a Chromium Carbide Metal Matrix Composite Coating for high temperature oxidation protection and special process for preparing titanium alloys to receive adherent brush plated deposits for OEM or salvage applications. The manufacturers of brush plating equipment generally offer a number of plat- ing solutions for each of the more important metals. One reason for this is to offer a choice in properties. For example, one user may want a hard, wear resistant nick- el while another wants an impact resistant, ductile coating. Since the ductility of metals, whether wrought, cast or plated, generally decreases with increasing hard- 345

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