Wheat Flour Milling, Second Edition
Pages 397-418
DOI: https://doi.org/10.1094/1891127403.013
ISBN: 1-891127-40-3
Abstract
The miller is responsible for two major categories that affect profit: the manufacturing cost to produce a unit of flour and the total monetary recovery from a certain quantity of wheat. To address these responsibilities, the miller must have the means to simultaneously control the whole operating system and make the right technical, economic, and management decisions. Optimum extraction rate is the major objective of the miller's efforts, in addition to the quality of the finished products and the capacity of the mill. The emphasis on these three objectives continuously changes, and an optimal economic balance among them must be found.
The mill's process control is related mainly to the technical aspects of the milling operation. Although the operation of the equipment and the monitoring of mill flow are largely automatic, with the help of sophisticated electronics, close specialized supervision of the milling process is necessary for an efficient and economical system. The wheat must be selected and mixed based on defined parameters and then cleaned and conditioned properly for milling. In the mill, the wheat is fed to the rolls and ground in ways that create the proper distribution of intermediate quantities and qualities to keep the mill in balance. Mill control requires the miller to set specific methods and guidelines for routine upkeep of an efficient operation. However, a control computer augments human capabilities by applying preplanned intelligence to the over-all economic operation of the process, which can result in 1) increased production and better utilization of equipment, 2) improved quality control and uniformity, and 3) reduced operating costs through better use of raw materials and reduction of losses and human errors. The most common functions of the computer that controls a flour mill were stated by Kuphal (1964):
- Controlling actuators and set points to guide the process,
- Scanning the process variables,
- Data logging, either on a demand or trend basis,
- Providing alarm signals when process variables reach their outside limits,
- Recording sequences of events,
- Calculating and reporting performance indexes,
- Providing information on operator demand,
- Start-up, shut-down, and control sequencing of processing and material handling equipment,
- Taking emergency action when required,
- Making multivariable control calculations and optimizing such calculations.
Goslak (2002) suggested an integrated system for a flour mill in which the production automation system is linked to the business and information systems over one common communication network. With such an integrated system, information can be shared among production, accounting and invoicing, quality control, production scheduling, and maintenance.
In addition, many indirect methods are used to control the mill, and these require the miller's skill and judgment. The miller tests and evaluates the wheat and the resulting flour, germ, and bran to determine mill adjustments that obtain the best performance. The relative amounts of products are expressed as functions of quantity and quality. To control the intermediate processes, i.e., the grinding stages in the mill, the miller uses the ash curve, distribution table, and sieve analysis, from which the granulation curve is generated. Such means give the miller a total picture of the mill's technical performance and permits evaluation of changes in raw materials, product quality, and mill efficiency.
