Performance evaluation of a hammer mill during grinding of maize grains

Robert Mugabi, Yusuf B. Byaruhanga, Kent M. Eskridge, Curtis L. Weller

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


The performance of a hammer mill fabricated in Uganda was evaluated and the optimal performance conditions were determined. The evaluation was done with screen hole diameters (S) of 1.5, 2.0, and 3.0 mm, hammer tip speeds (H) of 68.12, 81.81, 102.17 m s-1 and hammer thicknesses (T) of 4.0, 5.0, and 6.0 mm for determination of energy consumption and geometric mean diameter (GMD) using a modified central composite design (CCD) split-plot experimental design. Screen hole diameter and hammer thickness had significant effects on energy consumption (p<0.05). S and H had a significant effect on GMD but T did not have a significant effect on GMD. S and H had significant effects on both GMD and energy consumption. Quadratic effect of T, interaction effects of TH and HS also had significant effects on energy consumption. The hammer mill was most efficient with a hammer thickness of 5 mm, hammer tip speed of 83.57 m s-1 and screen hole diameter of 2.16 mm, both for energy consumption and flour GMD. The achieved impact energy calculated per unit mass, were 2.93 MJ t-1, 4.23 MJ t-1 and 6.60 MJ t-1 for tip speed settings of 68.12, 81.81, and 102.17 m s-1 respectively. Impact energy supplied did not have an effect on GMD. Hammer mill settings obtained should be tested on other grains.

Original languageEnglish (US)
Pages (from-to)170-179
Number of pages10
JournalAgricultural Engineering International: CIGR Journal
Issue number2
StatePublished - Jul 2019


  • Hammer mill
  • Impact energy
  • Particle size
  • Split-plot design

ASJC Scopus subject areas

  • Automotive Engineering
  • Agronomy and Crop Science
  • Energy (miscellaneous)
  • Industrial and Manufacturing Engineering


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