What is a Checkweigher System?
A checkweigher system is made up of a series of conveyor belts. These checkweighers are also known as belt- or chainweighers, but are most commonly known as the former. They are also referred to as in-motion scales, in-line scales or conveyer scales. They are usually coupled to an in-line system of conveyer belts.
This system is an automatic weighing machine that is primarily used to check the weight of a commodity, usually used within the food and packaging industries for accurate product weighing as a safeguard for both producers and consumers of these products.
Typically, it is used at the end of the production line process to ensure that the weight of the packaged commodity is as per a predetermined specification within a small variance of either up or down from that spec.
At this point, making use of the checkweigher system ensures that products on the production line outside of the weight specification variance, either up or down, are removed from the packaging process.
Depending on the size of the checkweigher system being used for this process, it will have the capacity to weigh all types of packaging. If the calibrations, specifications and settings are accurate and the product is within the minimum and maximum limitations of capacity of the machine, it would be able to complete this process at high speed with excellent results.
How the Checkweigher System Works
The checkweigher system is made up of various parts and is usually mobile. In other words, it is able to be disassembled, relocated and reassembled onto a different conveyor system in a different location within the factory or place of product processing.
Typically, the checkweigher is made up of various parts, the first being the three belts or chain beds.
- The inlet or infeed belt – This belt accepts the packages from the conveyor belts. It is positioned in line with the conveyor belts and, depending on the machine specifications, may be able to change the speed of the package and bring it to an acceptable speed required for weighing. The infeed is also sometimes used as an indexer, which sets the gap between products to an optimal distance for weighing.
- The weigh belt – This is mounted onto a weight transducer which is typically a strain-gauge load cell. This belt will weigh the product as per the predetermined specifications. Some weigh belts will have individual weight digital display readings along with alarm lights.
- The reject belt – This is the belt that provides a method of removing a package outside of the programmed specifications, including variances (over or under) from the conveyor belt.
The reject process varies from product to product. Some lighter weight products need compressed air (or pneumatic) systems to blow small products off the belt, but heavier product applications require paddle arm actuators that will swipe the product from the conveyor to either an overweight or underweight bin. Some fragile products are rejected by “dropping” the bed so that the product can slide gently into a bin. Sometimes, other sets of conveyor belts can replace the reject bins to move the rejected items to other areas of the production floor.
Read more on How to Choose Industrial Weigh Machines.
Optional Extras
Another additional or optional part for the checkweigher system is alarm lights. This is a light cluster that can be attached to the weight belt. It usually has a green, amber and red light and can be mounted above or next to the digital weight display panel.
As the product or package passes over the weigh belt, the weight of that individual item will register on the weight display panel. Should the item be in line with the predetermined specifications for the product line, the green light will activate.
Should the same item register a weight that is not exactly in line with the predetermined specifications, but it does fall within the predetermined variance, the amber light will activate. The red light will activate should that same item fall outside of the predetermined weight and variance percentage, and is therefore either over or under that weight.
In most checkweigher systems, the speed of counting the product you are producing is adjustable.
As the market leader in weighing scales with more than forty years’ experience and a footprint in most African countries, Teroaka are able to assist you with ongoing sales and service for your very own checkweigher system which is custom made to your specific needs. Visit our website or contact us directly for more information on our checkweigher systems.