Example 5 Plate Thickness Variation in a Workpiece Plated without Use of Conforming Anodes

A cylindrical, cup-shape production part that was plated without the use of conforming anodes is shown in Fig. 6. Thickness of plate varied from a minimum of 6 pm (240 pin.) to a maximum of 25 pm (1000 pin.).

Fig. 6 Variations in plate thickness obtained on a workpiece plated without the use of conforming anodes

Conforming Anodes. Parts of complex shape with stringent dimensional requirements, such as those shown in Fig. 7 and 8, require the use of special techniques, conforming anodes, and shields, in order to obtain the required uniformity of plate thickness.

Fig. 7 Application of shields to obtain shim having a uniform cadmium plating. The 305 mm (12 in.) long and 38 mm (1 in.) wide shim was plated to the required thickness of 13 ± 5 pm (520 ± 200 pin.).

Fig. 7 Application of shields to obtain shim having a uniform cadmium plating. The 305 mm (12 in.) long and 38 mm (1 in.) wide shim was plated to the required thickness of 13 ± 5 pm (520 ± 200 pin.).

Fig. 8 Couplings that were uniformly cadmium plated with the aid of a 6.4 mm (1 in.) diameter anode

centered in the bore during the plating operation. Plating thickness ranges from 8 to 13 pm (320 to 520 pin.). Example 6: Application of Shields to Produce Uniform Cadmium-Plated Shim.

A shim, 305 mm (12 in.) long by 40 mm (14 in.) wide by 2.4 mm (0.095 in.) thick, is shown in Fig. 7. Parallelism of all sides, as well as plate thickness, was extremely critical. When this part was plated in a simple rack, plate thickness varied from 13 ^m (520 ^in.) at the center to 50 to 75 ^m (0.002 to 0.003 ^in.) at the edges and ends.

By using shields that approximated the outline of the shim, it was possible to plate cadmium all over to a depth of 13 ± 5 ^m (520 ± 200 ^in.). The part was gently agitated in a still bath.

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