Is your checkweigher accurate?

Is your checkweigher accurate?


Durable dynamic checkweigher use in industry.

Checkweigher use in industry
In order to comply with regulatory requirements and achieve accurate operation, the accuracy of the checkweigher needs to be tested. In this article, we try to use the simplest language to explain how the user of the checkweigher should accurately measure and determine the accuracy of the checkweigher.

         In any weighing equipment, there are two kinds of errors that can have a significant impact on the accuracy of the equipment. One is repeatability, and the other is accuracy, which is the accuracy of the weighing result compared to a known weight (such as a weight). These two parameters are also the only two comparable parameters for dynamic checkweighing (online automatic checkweighing) and static weighing (static scale). In some documents, you may read some other parameters, such as environmental conditions, temperature, measurement uncertainty, product properties, tare weight, air buoyancy, and so on. Forget all these parameters, we will use the products that need to be checked in the environment for testing.
There are two small tests that can help you use your dynamic checkweigher with peace of mind, but before introducing these two small tests, we must first point you to two wrong practices.

        The biggest misunderstanding of online checkweigher testing is to use the method of calibrating a static scale to test the checkweigher. Stop the conveyor belt, place an object on the weighing belt, read the weight, and see if the weight you know matches. This approach is completely wrong. When the conveyor belt is turned on, the checkweigher will vibrate more and run in a moving state, which will bring more errors and cannot be directly compared with the test results in a static state. This is why the sensor of the dynamic checkweigher needs to be specially designed to meet the specific accuracy requirements. In fact, the value obtained by placing the object in a static state is only used by the service engineer as a starting reference point for determining the dynamic weight. For example, when an automatic checkweigher is at rest, the weight of an item is 500g, and when the checkweigher is moved, it weighs the same object, and the weight obtained becomes 502g. At this time, the checkweigher needs to be calibrated, minus 2g. Generally speaking, the current checkweighers can place static reference objects, then compare and automatically adjust this value.

        Another wrong approach is to take an object of known weight, such as a weight, and read the value through a belt to confirm whether the scale is accurate. Even if the weight of this weight is equal to the weight of your product, it may cause large errors due to its dynamic properties (such as different lengths and shapes) during belt transmission.