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Improving Performance of Locally Fabricated Hammer Mills Used in Uganda

Robert Mugabi, University of Nebraska - Lincoln


The hammer mill introduced to Uganda 60 years ago is still the main equipment used in milling most of the cereals such as maize and sorghum. Hammer mills are very important in Uganda and neighboring countries as a time-and cost-effective means of milling grains. These are mostly manufactured by in-country artisans and often of low efficiency. Some concerns with locally fabricated hammer mills include: long milling time, contamination of flour with steel filings due to the low quality of the steel alloy used to produce the hammers and excessive wear and tear, as well as low time and energy efficiency. The goal of the study was to improve the performance of the locally fabricated hammer mills in Uganda. The protocol generated for testing the performance of hammer mills was integrated with the local commonly practiced testing methods used by fabricators. This improved protocol was then applied to test performance of a commonly used hammer mill. This was in turn assumed to improve the operations of the millers and result into consistent and safe products. First, the test protocol can be used by small scale fabricators given their constraints of available equipment and resources. The protocol evaluated the performance of locally fabricated hammer mills in Uganda by measuring the final particle size, power/energy consumption and milling rate. Subsequently, an informal survey was conducted in Mpigi, Mukono, and Wakiso districts in Uganda. The challenges and opportunities of local fabrication of agro-processing machinery in Uganda were studied with a review of secondary data sources and policies. The survey was complemented with key informants’ interviews, on-spot inspection and assessment, and photographic documentation. During the survey, samples of hammers were collected and a rate of wear and hardness study was also carried out. Iron fillings concentration of ~6.48 ppm was observed. Performance evaluation of a locally fabricated hammer mill was also done. Best operating settings with maximum energy efficiency and most uniform particle size were determined and found at hammer thickness of 5 mm, hammer tip speed of 83.57 m s-1 and screen hole diameter of 2.16 mm.

Subject Area

Food Science

Recommended Citation

Mugabi, Robert, "Improving Performance of Locally Fabricated Hammer Mills Used in Uganda" (2017). ETD collection for University of Nebraska - Lincoln. AAI10271333.