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How To Ensure The Measurement Accuracy Of The Dynamic Checkweigher?

Jun 18,2022


Overview of Checkweigher

The automatic checkweigher can read the weight of products on the inspection production line at high speed and dynamically, and can continuously detect the products with unqualified weight in the production line, and perform up and down line discrimination or automatic weight classification according to the preset value, especially suitable for packaging products and checking for missing parts. The packaged products are weighed and tested by the checkweigher, and the qualified ones are returned to the original conveyor belt, and the unqualified ones are rejected (or alarmed and stopped), and it has the functions of classifying and counting the products according to the settings.


Several factors affecting the dynamic checkweigher

The accuracy of a dynamic checkweigher can be defined as: a single object is weighed several times on a dynamic checkweigher, and the standard error of its weight value (premise: average error = 0)

The most important evaluation indicators for the accuracy of the dynamic checkweigher are the average value and standard deviation.

Average: The value obtained by dividing the sum of a group of data by the number of this group of data.

Standard deviation: a measure of the degree of dispersion of the data distribution, used to measure the degree of deviation of the data value from the arithmetic mean

Usually, we define the dynamic accuracy of a checkweigher with ±3 times the standard deviation. If for a given product, under certain testing conditions, the smaller the standard deviation value, the higher the dynamic accuracy of the equipment . What needs to be clear is that the dynamic accuracy must be the accuracy under the premise of a given product, a given detection condition and a given precision definition method. Generally speaking, if the detection accuracy is high, the detection speed should be lower. If the detection accuracy is low, the detection speed can be higher.



The main factors affecting the accuracy of the dynamic checkweigher

(1) Product factors

①Product category (such as appearance, solid or bottled liquid, etc.)

②Product weight

③ Throughput (belt speed, weighing time, length of weighing table

④The stability of the product passing (center of gravity, bottom flatness, surface reflectance, etc.).


(2) Environmental factors

①Temperature, humidity, etc.

②Factors such as airflow, ground vibration, and belts scraping each other


(3) Human factors

①Inappropriate use and incorrect settings

②The level of the machine, etc.


Basic methods and requirements to ensure the accuracy of dynamic checkweighers

(1) Ensure accuracy by ensuring the passing status of the product being tested

Due to the diversity of the products to be tested, the state of the weighing part of the tested object passing through the online checkweigher has a great impact on the accuracy of the checkweigher, that is, it is necessary to ensure that there is only one product on the weighing platform at a time. The stability of the tested product on the weighing table is also an important factor affecting accuracy. When the tested product enters the weighing part through the guiding conveyor, a smooth transition must be ensured to prevent possible tilt, jump, etc., which may cause the weighing table to shake and affect the accuracy. In this case, a transition device can be added to the connection of the conveyor, such as a transition slide, a ball transition plate, etc.


(2) Ensure accuracy by improving the equipment operating environment

The dynamic checkweigher is a high-precision re-inspection equipment. Usually the weight value of the test object is very small, and the weighing accuracy will be more sensitive under high-speed operation, and it is affected by many environmental factors, such as the working environment. Temperature, humidity, static induction, radio frequency interference, ground vibration, air circulation, etc. Therefore, the use environment of the dynamic checkweigher is also a key factor to ensure accuracy. First of all, try to put the dynamic checkweigher in a suitable and constant working environment with suitable temperature and humidity to avoid unstable and irregular changes in various indicators.



(3) Ensure accuracy by improving production technology

The working state of the dynamic weight-reducing scale is weighing under high-speed operation, which puts forward higher stability requirements for the conveying equipment participating in the weighing. Therefore, the conveying mechanism of the weighing part must minimize the noise and vibration during operation.



The accuracy and speed of checkweighers under actual conditions need to be comprehensively evaluated based on many factors. Shanghai Shigan Industrial Co,.Ltd is a manufacturer specializing in the production of checkweighers. It has many years of manufacturing experience. If you have any questions, please feel free to contact us, we There are 24 hours professional online to serve you.