Multi-Criteria Analysis of Hammer Mill Design Selection for Coal Fertilizer Production

Abstract

The hammer in a hammer mill is a critical component that determines the efficiency of coal crushing in the coal fertilizer production process. The selection of the appropriate hammer design cannot be based solely on structural strength, but must also consider production cost efficiency simultaneously. This study aims to evaluate and rank three alternative hammer mill designs based on a combination of technical performance from Finite Element Analysis (FEA) results and production costs, using secondary data already available in reference theses without new data collection or experiments. The data used include Safety Factor, impact area, maximum displacement, maximum von Mises stress, and production costs for nine samples (three designs x three materials). Because railway track materials do not have a valid selling value according to applicable regulations, six samples with commercially viable materials (alloy steel and manganese iron) were determined as decision alternatives. The Simple Additive Weighting (SAW) method was applied with objective criteria weighting based on the Shannon entropy method to avoid subjectivity in determining the weights. The analysis results show that Design 3 with manganese iron material (Sample 9) obtained the highest SAW score (0.696), followed by Design 3 with alloy steel material (Sample 8, 0.677), while Design 1 with both materials ranked the lowest. Sensitivity analysis through five weighting scenarios and ±20% weight perturbation test showed that Design 3 consistently ranked one of the top two in all scenarios, indicating the robustness of the decision results to changes in decision-maker preferences. This study provides a methodological contribution in the form of an integrated technical-economic decision-making framework that can be replicated for other machine component design selection cases based on existing FEA data and production costs.