6. Power-Supply Setup, Surface Area, and Current Density

Current density

Current density expresses current per unit of plated surface area.

Current Density = Current / Surface Area

Current = Surface Area × Target Current Density

Common units are amperes per square foot (A/ft²) or amperes per square decimeter (A/dm²).

A broad nickel electroplating working region may be roughly 10–50 A/ft², but the correct range comes from the commercial chemistry supplier.

Surface-area calculations

Flat plate, both large faces only

Area ≈ 2 × Length × Width

Add edge area when thickness is significant.

Rectangular block, all faces

Area = 2(LW + LH + WH)

Cylinder

Side area:

Area = π × Diameter × Length

Add end areas if exposed.

Example

A rectangular part is 12 in × 6 in × 0.25 in and all faces are plated.

Area = 2[(12×6) + (12×0.25) + (6×0.25)] Area = 153 in²

Convert to square feet:

153 / 144 = 1.063 ft²

At a specified 25 A/ft²:

1.063 × 25 = 26.6 A

Rectifier setup

1. Calculate exposed area.
2. Select current density from the product specification.
3. Calculate required amperage.
4. Make all electrical contacts before energizing.
5. Ramp or apply current according to the process specification.
6. Verify actual amperage.
7. Watch high-current areas for burning.

Voltage

Do not chase a particular voltage unless the process explicitly requires it. In most nickel electroplating work, amperage/current density is the primary electrical control variable.

Parallel parts

Add the exposed area of every part on the rack, then calculate total current from total area.