Miller Magazine Issue: 113 May 2019

49 COVER STORY MAY 2019 coarser than semolina and are not as pure as semolina. 4. Reduction System: The reduction system also consists of a series of rollers and sifting machines after each roller. However, the surface of the reduction rollers is not corruga- ted as the breaking rolls, but it is smooth. The duty of redu- ction system is to refine pure endosperm particles coming from the sifting of the sizing system and the purification system and turn into flour at desirable fineness. In the redu- ction system, it is essential that the material is refined while controlling the damage of starch granules and the minimum abrasive of bran particles. This process is done again gradu- ally, at the end of each stage a part of the flour is separated, and the larger material is sent to the next stage. MILL ADJUSTMENT It is wrong to think that “The flow diagram will be kept constant during operation of the mill once it is designed in the mill design.” On the contrary, the current flow sheet should be reviewed from time to time according to condi- tions such as wheat characteristics, climate conditions, and flour quality and the required adjustment should be carried out. But, it should not be changed too often. An experien- ced person should know the overall diagram of the mill and must work on it first when it is necessary to make a chan- ge. In order to determine whether a change in the flow sheet is necessary, the products and the mid products are checked regularly after being visually analyzed. Generally, it is necessary to try to change the proportions of conditio- ning, breaking release , and purifier material before making changes in the flow diagram. The objectives of changing flow diagram: a. To obtain the highest flour yield from the mill. b. To produce flour with the least possible ash. c. To ensure that the characteristics of the flour are ap- propriate to the market requirements and purpose. The flow sheet is regarded as the most important tool for miller, mill engineer, and even production and quality team to engage close communication. After the new mill is installed and in the process of operation or in the case of the approp- riate use of the flow sheet of the previous mill, the flow sheet plays a critical role in the mill performance. In other words, the correct diagram is the key to success in grinding. In the suc- cess of mill design and diagram, it is crucial how equipment is in line with the objective and to use the equipment with the optimal setting. Mill diagram is one of the factors affecting the profit of the enterprise. Production costs play a role in the profit of enterprise, and mill performance is influential in production costs. Mill performance is evaluated with different parameters. However, the measurements used to determine mill performance, in general, can be listed as follows. a. Total flour yield or extraction rate for specific ash con- tent from milled wheat. The flour yield is the first parame- ter that defines the production cost of products. b. The ratio of acquired high quality (first clear flour) in contrast to low-quality flour (second clear flour) from the mill. c. The flexibility to mill many types of wheat. In some cases, it is required to grind hard, soft and even durum wheat. In this case, the flow sheet should be appropriate, and there should not be many problems in the transition from one wheat to another. d. Flexibility to produce different products. The type of flour required from the mill may vary according to market requirements. It requires the flow diagram to be flexible. Although the flow diagram is as simple as possible, it beco- mes more complex to provide flexibility. e. Energy efficiency. It is the amount of energy required to produce unit flour. This is directly related to the flow sheet. f. Production stability. For high-capacity enterprises, flour with stability properties is very important. The flow diag- ram is of great importance for obtaining stable flour. MILL BALANCE As long as materials in the mill work according to calcu- lated flow amount at design, it is said that mill is in balan- ce. Even if the mill is well-designed and suitable machines are selected, the mill’s performance is reduced and good results are not achieved if it is not precisely adjusted by an experienced person. In order to maintain the balan- ce or even have a good balance, all the milling machines must be adjusted. To achieve optimum efficiency in the operation of all machines, all machines must be operated at the optimum setting, and all tools of the mill should be fed with the correct quality, size, and appropriate amount of material. The deviation in a machine affects the per- formance of subsequent tools because the balance of the material coming there is disturbed. For good adjustment of the machine, it is necessary to analyze the properties of the material well and to know where and how to adjust accordingly. To reach the balance of the mill, the adjustment should be carried out by testing periodically when raw material or mid products are changed. For this, ash curve, granulation curve, and distribution table are found out. These provide useful information to the miller about the total performan- ce of the mill, the quality of the raw material, and the effi- ciency of the mill.