FAQs on milling
I have drawing of Rice Mill RM 150. The drawing seems to come from IRRI, Agricultural Engineering Division, Los Banos, Laguna, Philippines. Could you inform me more about the performance of this type of machine before we begin to fabricate it as a model for our local rice farmer? If you have better one, can we get the drawing?
The Rice Mill RM 150 (micro mill) is indeed an old IRRI design based on the Engleberg principle and adapted from Chinese mills for production by local workshops. The major modification is that the rotor is not made from cast iron but instead it can be assembled from local materials using welding technology only. The design has not been updated since it was released so the drawings you have are the current ones.
The Micro Mill is a single stage mill which means that the de-hulling and the polishing are done by the same rotor. The head rice recovery (based on paddy weight, note that this is different than the info you might have which is based on total white rice weight) is therefore relatively low.
The Micro Mill can be nevertheless useful for farmers groups located in remote areas like the mountains of Tanah Toraja in South Sulawesi, Indonesia. In those mountains, where there is no access to commercial mills and farmers have to walk for hours to get their rice milled or have to use manual milling techniques, the micro mill was well accepted because it was reducing drudgery. In that case the milled rice is used for home consumption and high head rice recovery is not so important. The farmers used the byproducts (bran and small brokens) for feeding their own animals.
However, for rice traded in the markets we think there are better solutions like smaller two stage mills with rubber roller de-husker because it has better head rice recovery and thus lower losses.