The advance amount refers to the advance stop amount of the feeding process, which is an important working parameter of the electronic quantitative packaging scale. Generally, the quantitative packaging control instrument provides three-stage feeding control: fast feeding, medium feeding, and slow feeding (also called: large feeding, medium feeding, and small feeding). The corresponding advance stop amounts are: fast feeding advance stop amount, medium feeding advance stop amount, and slow feeding advance stop amount. Basically, any quantitative packaging scale will use these three parameters.

In the process of feeding the packaging scale, there is a certain drop between the material from the feeder outlet to the metering device, which may be high or low but feels to exist. The material suspended in the air caused by this drop is called the air drop amount L. In the feeding process, once the weight of the metering device reaches the target value M and the feeder is immediately closed, the actual weight at this time is equal to the target weight M plus the air drop amount L, that is, the actual weight = M+L. This is because the air drop amount always exists and cannot be discarded.

In order to facilitate the control of the feeding accuracy of the electronic quantitative packaging scale, the lead parameter is set in the program. Just like the example mentioned above, if we have the lead parameter, we can set its size equal to the air drop. In this way, when the target weight M-L is about to be reached (there is still air drop), the feeding mechanism will be stopped in advance. After stopping the feeder, the material L with air drop will then enter the metering device, so that the correct weight M can be obtained.

In practical applications, quantitative packaging scales generally have three-stage feeding, for example: three-speed spiral feeder feeding, we can set the spiral to 100 rpm when fast adding, 50 rpm when medium adding, 10 rpm when slow adding, the target quantity is 25KG, and then the fast adding lead is set to 6KG, the medium adding lead is set to 3KG, and the slow adding lead is set to 0.1 kg. Then the working range of fast adding is 0-19, medium adding is 19-22, and slow adding is 22-24.9. Is this correct? The answer is of course not, because there is still the difference in weight that has not been considered. For example, the fast feed stops when it reaches 19 kg, but with the difference in weight in the air of the fast feed, the actual weight may have reached about 20-21 kg when it is transferred to the medium feed. Similarly, after the weight of the medium feed reaches 22 kg, it is transferred to the slow feed. When the slow feed starts, the actual weight may have reached about 23-24 kg. In the end, the actual weight left for the slow feed is about 1 kg.

In actual work, the setting of the advance amount of fast feed, medium feed, and slow feed is used to make the electronic quantitative packaging scale complete the feeding process in the shortest time, and the accuracy is not greatly affected when there is a lot of material or a little material. This is the purpose of adjusting these three advance amounts. Therefore, when adjusting these three parameters in actual work, it is necessary to adjust them in combination with the feeder. For example, if the spiral speed set before is changed, the block feed, medium feed, and slow feed also need to be adjusted to achieve the best packaging speed and accuracy.