The Secret of Precise Filling Materials in Powder Packaging Machines

From the perspective of quantitative principles, powder packaging machines mainly have two methods: volumetric and weighing.

(1) Fill by volume

Volume based quantitative filling is achieved by controlling the volume of the filled material. The screw based quantitative filling machine belongs to the category of volume based quantitative filling. Its advantages are simple structure, no need for weighing devices, low cost, and high filling efficiency. The disadvantage of screw type quantitative powder filling machine is that the filling accuracy varies greatly depending on the different materials being filled, mainly relying on the stability of the apparent density of the filled materials, the uniformity of material particle size, as well as the moisture absorption and looseness of the materials. Therefore, volumetric filling is mainly suitable for material particles with uniform particle size, stable bulk density, and good self flow properties.

Volume based quantitative filling packaging can be divided into two forms according to the different measurement methods of materials:

1. Control the flow rate or time of the filled material to control the filling volume, for example, by controlling the number or time of rotation of the screw in the screw filling machine to control the volume of the filled material, and by controlling the vibration time of the vibrating feeder to control the volume of the material.
2. Using the same measuring container to measure materials for quantitative filling, such as using a measuring cylinder, measuring cup, or plunger type quantitative filling machine.

Regardless of which volumetric quantitative filling method is used, there is a common problem, which is to ensure the stability of the bulk density of the filled material as much as possible. To achieve this requirement, methods such as vibration, stirring, nitrogen filling, or vacuum pumping are often used. If high filling accuracy is required, it is necessary to use an automatic detection device to continuously detect the changes in the apparent density of the filled material, and then continuously adjust it to ensure the accuracy of the filling volume.

(2) Fill by weight

The metering filling system mainly consists of a driving motor, a storage device, a screw, a screw installation sleeve, and so on. The rotation feeding of the screw is provided by a servo motor, and the power is transmitted synchronously between the two, which can control the number of screw rotations and improve the accuracy of feeding. The servo driver drives the servo motor to rotate the corresponding number of turns based on the input signal of the PLC, and drives the screw to rotate through the synchronous belt to complete each filling and feeding process.This can precisely control the precision of each filling material in the automatic powder packing machine