

Subtractive scales are production metering equipment for the formulation, feeding and discharging of liquid and powdery materials, all controlled by computer, weighing and measuring, and continuous transportation. According to the pre-determined mass ratio, the balanced weighing of several substances in the weighed material for dosage and measurement. In addition to the hopper, there are dynamic weighing modules, precision amplifiers, analog/digital converters, micro-computers, monitors, printers and execution systems. The computerized control system is capable of controlling several dosage and agitators, as well as controlling the time of dry and wet mixing for weighing and flow control, thus realizing precise metering and dosage.

The reduction scale adjusts the speed of the discharge screw machine according to the rate of weight reduction. When the weight of the weighing meter is less than the lower limit of weighing, the speed of the discharge screw is fixed to start the rapid loading equipment, and the loading stops when the material is loaded to the upper limit of weighing. According to the rate of reduction of the weight of the material in the hopper scale to control the speed of the discharge screw machine, in order to achieve the purpose of quantitative feeding, when the material in the hopper scale reaches the lower limit of the position of the weighing, the discharge screw machine is in accordance with the rotational speed of the fixed amount of material at that time, at the same time the material in the silo quickly down to the hopper scale, so shortening the feeding time, but also to improve the accuracy of the weighing and the control of the precision.
The subtractive scale weighs the sample and the weighing bottle first, then removes the required amount of specimen, weighs the remaining sample and the weighing bottle again, and the difference between the two weighings is the weight of the required specimen. The material is rapidly discharged from the silo to the hopper scale, and the speed of the discharge screw machine is controlled to adjust the discharging rate to achieve the purpose of quantitative feeding. By controlling the speed of the discharge screw machine to control the rate of discharging, so as to realize the accurate control of the weight of the material. The design principle of the reduction scale focuses on the fast discharging of the weighing bin, the precise control of the discharging screw machine and the setting of the lower and upper weighing limits to ensure that the material can be discharged at the set rate and to improve the accuracy and control precision of weighing.
The reduction scale can be divided into weighing and counting. Firstly, the item to be weighed is placed on the reduction scale, then the scale is turned on and the weight of the item will be measured by the sensor. During this process, the reduction scale will count the measurement results at fixed time intervals and display the results on the scale. Finally, depending on the desired level of accuracy, the weighing results are rounded up or down to get the final accurate weight data. The inside of a reduction scale usually consists of an Electronic scale and a series of controllers, sensors, etc. that work together to perform measurement and calculation tasks.