Although conveyor scales and checkweighers appear to be very similar, they are two entirely different entities. The ultimate difference between them is that one is a system and one is a component to be part of a system.
The in-motion checkweigher is defined as a system because it is formed of several components that form a single working unit. It is composed of an infeed conveyor, a conveyor scale, and an outfeed conveyor with some sort of diverting device, all as one unit.
The sole purpose of a checkweigher is to take a weight and check that against a user-specified range. If a product is inside this range, it passes through, down the conveyor. If not, the divert rejects the product onto another conveyor or container to be disposed of or reworked. This is all decided by software that is unique to the checkweigher.
Notice that a conveyor scale was just a single component of the checkweigher itself. A conveyor scale simply generates the weight of the product as it passes over. This makes it versatile.
A conveyor scale can be connected to a sortation system or an automatic labeler quite easily so that these systems can receive accurate weight information. Simply put a conveyor scale is just that – a scale that weighs products as it is conveyed over the scale’s live area, without stopping.
A checkweigher is more akin to a combo of conveyor scale and sortation system, except the sortation system only has two options: pass or fail.
As an example of how they differ in practice, let’s look at a producer that uses fixed weights and another that labels by weight (catch weight). For the former, a checkweigher is going to be far handier than just a conveyor scale because it can be programmed to reject any product that is below the minimum weight. Likewise, a conveyor scale is more valuable in the latter because it can link to a weigh price labeler and is capable of relaying individual weights to any number of systems.
The difference isn’t always obvious, but it is important to know the industry lingo when it comes to automatic systems.
It can save you a lot of trouble in the long run!
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