Another way to look at maintenance is to divide it into two concepts: maintenance related to general operational equipment and maintenance related to the ability of the equipment to efficiently perform milling technology functions.
General maintenance includes upkeep of electronics, mechanical parts such as bearings and other components, and electrical motors, just to name a few areas. Specific technical maintenance includes maintaining roll surface condition, bolting screens, and filter stockings. The general maintenance program is scheduled, as in other processing plants, but technical maintenance is scheduled after careful consideration of production, market demand, equipment, manpower, and labor costs. For example, many mills schedule maintenance on Monday rather then the weekend to avoid paying premium time for labor, to avoid having pack and load weekend production in storage, and to have the full management and supervisory staff available if needed.
Bucket Elevators and Conveyors
The best way to inspect the grain transport equipment is visually, when it is not in operation. This activity must be planned on downtime, usually on premium time; therefore, it should be well organized. Records of the inspection of and complete specifications for the buckets, belts, and conveyors should be maintained. The elevator belt should be turned slowly, and the condition of the belt and buckets observed as they pass the inspection opening. If the belt looks worn, the complete belt and buckets should be made ready and replaced during a scheduled downtime. An old, worn, or damaged bucket can be replaced during the inspection. It is important to tighten and align the belt so that the buckets do not strike the leg housing. The discharge from the bucket elevator should be checked to prevent backlegging (material falling into the down side of the leg). The bucket elevator leg is one of the largest producers of dust in the mill and accordingly is the most dangerous place for concentration of dust. In the process of inspection and maintenance, it is important to adhere to national regulations, such as to those of the U.S. Occupational Safety and Health Administration (OSHA). OSHA regulations require that bucket elevators use static conductive belts with an inspection port and have externally mounted bearings, motion devices, and belt alignment devices . The screw conveyor drives, couplings, bearings, and flights need periodic replacement. Wear can be observed when the conveyor is not in operation. The alignment of the conveyor is very important and must be done properly to ensure the conveyor’s long life.