Effect of current distribution on angle position and current operation time in electroplating bolts

A popular solution to prevent metal structure rusting is to add a protective layer using electroplating. One of the design problems involving the electroplating process is the selection of structural geometry. It is crucial to determine current density, distribution and thickness of the resulting coating. The aim of this study was to investigate the effect of current distribution on the cobalt alloy coating of bolts. The current distribution was varied by changing the angle of the substrate (bolt) hanging on the cathode at 45 degrees and 90 degrees angles to the anode (platinum), respectively. The effect of prolonged current operation was also investigated from 30 minutes to 90 minutes. The product was then tested for its coating quality, surface roughness and hardness. Positioning the bolt angle at 45 degrees improved the coating and hardness especially on the uneven threaded part of the bolt. The surface roughness was higher on the coated bolt at 45 degrees and 90 minutes. A multi-layered coating formed in certain areas was prone to excessive current distribution and prolonged current operating time. The results obtained are useful as guidelines on the coating process for joining products.