South Africa has implemented various process-control systems to enhance metallurgical operations, aiming to improve efficiency and reduce costs. A DID model was applied to compare pre- and post-intervention data from selected metallurgical plants, accounting for potential confounders through instrumental variables. The analysis revealed that the implemented process-control systems led to an average cost reduction of $50,000 per month in monitored operations. The DID model provided robust evidence on the financial impact of these systems but acknowledged limitations due to varying operational conditions and data availability. Future studies should consider broader regional impacts and long-term economic outcomes for sustained cost savings. process-control systems, metallurgy, South Africa, difference-in-differences (DID), cost-effectiveness analysis The maintenance outcome was modelled as $Y_{it}=\beta_0+\beta_1X_{it}+u_i+\varepsilon_{it}$, with robustness checked using heteroskedasticity-consistent errors.