Check weigher

It is normally found at the offgoing end of a production process and is used to ensure that the weight of a pack of the commodity is within specified limits.

[1][2] A checkweigher can weigh in excess of 500 items per minute (depending on carton size and accuracy requirements).

Checkweighers can be used with metal detectors and X-ray machines to enable other attributes of the pack to be checked and acted upon accordingly.

Typically, there are three belts or chain beds: For high-speed precision scales, a load cell using electromagnetic force restoration (EMFR) is appropriate.

This kind of system charges an inductive coil, effectively floating the weigh bed in an electromagnetic field.

A dynamic, in-motion checkweigher takes samples, and analyzes them to form an accurate weight over a given time period.

Once the trigger fires, there is a delay set to allow the package to move to the "sweet spot" (center) of the weigh bed to sample the weight.

There are several tolerance methods: There is also a requirement under the European Average Weight System that data collected by checkweighers is archived and is available for inspection.

Most modern checkweighers are therefore equipped with communications ports to enable the actual pack weights and derived data to be uploaded to a host computer.

In some cases the dynamic scale sends a signal to a filler, for instance, in real-time, controlling the actual flow into a barrel, can, bag, etc.

Speed and accuracy that can be achieved by a checkweigher is influenced by the following: In-motion scales are dynamic machines that can be designed to perform thousands of tasks.

Some are used as simple case weighers at the end of the conveyor line to ensure the overall finished package product is within its target weight.

Checkweighers can be built with metal detectors, x-ray machines, open-flap detection, bar-code scanners, holographic scanners, temperature sensors, vision inspectors, timing screws to set the timing and spacing between product, indexing gates and concentrator ducts to line up the product into a designated area on the conveyor.

They can be designed in many shapes and sizes, hung from ceilings, raised on mezzanines, operated in ovens or in refrigerators.