Unlike standard scales a checkweigher is an inline device that automatically weighs each individual product as it moves past on a conveyor belt.  This continuous flow keeps production rates and through-put high and allows food producers to maximize there production capabilities. 

What happens to a product when it is either over or under weight?

As the package travels past the ‘load cell’ and is weighed a complex calculation is done to check if the package weight falls between the high and low limits set by the operator.  If the package falls outside this range an automatic rejection device removes the package from the product flow.  Typically this would be a kicker, diverter, air blast or lane diverter.  The removed package can then be further ‘worked’ to either remove or add product to the correct weight.

Many inline checkwieghers are either installed just after or just before a conveyor metal detector.  This ‘combo’ is often offered by both manufactures as an integrated system.  One can alert the other that a package needs to be rejected and the second device will ignore the package.  Both systems can then use the same rejection device cutting down on costs, space and maintenance issues.  

When looking for a checkweigher remember to understand clearly what you’re goals are and what the manufacturer is willing to guarantee.