Development and Performance Evaluation of a Mix-Kneader for Drying Soap

Soap is a salt of fatty acids obtained worldwide from mainly agricultural products and by-products such as plant (vegetable) oils (Yahaya et al., 2012). Drying neat soap is one of the key steps in the process of manufacturing bar soap. Currently, small and medium-scale local processors in Uganda rely entirely on tarpaulins and buckets to dry neat soap. These methods are labor intensive and take a lot of time (about 24 hours) to dry soap from 29-35% (w.b.) to the required moisture content of 15% – 21% (w.b.). Therefore, the aim of this research was to develop a Mix-kneader for drying soap in order to boost local production of bar soap. First, the different parts of the machine were designed and sized with the help of Solid Edge ST9 mechanical computer-based software. Fabrication of the component parts was done and finally, performance evaluation of the machine was carried out. At ‘No’ load test, the results indicated that the machine can run freely without too much noise and there were no visual breakdowns. At ‘Full’ load test, the Mix-kneader was able to dry 180 kg of neat soap in an average time of 15.5 minutes. The average machine capacity was approximately 560 kg/hr with a drying efficiency of 83.4%. The drying rate of the machine was calculated as 2.13 kg of water per minute. The material wastage was calculated as 1.31% which can be attributed to the fabrication errors. The developed Mix-kneader is affordable to processors and can be fabricated from any workshop within the country since it was developed from locally available materials.