Plating baths processess control

Authors consider the algorithms and control systems for the operation of electroplating tanks, allowing to solve the problems of a plating line efficiency, surface properties improvement (metal distribution, microhardness, etc.) and bath components concentrations maintained within the prescribed limits.
Current density at the cathode, temperature of the solution, the position of the sections of a mosaic anode, every section of which can move across the space of the tank, voltage from the independent current sources supplied to every section of the mosaic anode, the shape of the shaped anode, the parameters of the reversed current, or pulse current, the shape and location of the bipolar electrode in respect to the anode and the parts on the racks are used as the control actions.
To calculate the best uniformity of the deposited coating the mathematical models which describe the electric field in the plating tank and the corresponding software for the solution of the system of equations of the mathematical models have been developed. The utilized mathematical models include Laplace's equation with nonlinear boundary conditions of the third order, with the polarisation of the electrode taken into account Ohm's law in the differential form and Faraday's law. The calculation program gives the quantitative solution for any type metal and any type of the bath, including the cases of the nonlinear polarisation curve (as well as N-shape curve, for example for chrome plating in the standard solution).
The software for various geometry of the parts has also been developed. The source information, namely the drawing of a part, is transformed in to the wire-frame model and then in to a three-dimensional polygonal model. After that the coordinates of the surfaces of the part are entered into the electric field calculation program by the user to optimise the current distribution. In addition, the surface area of the part (for the subsequent calculation of the concentration changes of solution components) and the area of the surfaces faced to the anode are computed. 
After entering the geometrical parameters of the part the program solves the problem of obtaining most uniform distribution of the coating. The result is the metal distribution on the surfaces of the component.