Successful check weighing is the suppression of undesirable dynamic effects.
Over the last 40+ years, Thames Side has specifically developed a range of load cells and instrumentation/electronics designed for accurate, high speed weight measurement and detection of over- or under-weight in check weighing applications.
A check weigher is an automated system designed to check the weight of packaged commodities, to satisfy internal controls and external trade applications. They are usually found at the end of a production line in many industries, or in the despatch area of eCommerce warehouses.
Check weighers used in legal-for-trade applications require the use of approved components such as load cells and measuring electronics.
There are 2 main types of check weigher;
- Only the package content is checked; this is needed to calculate a price based on the content
- The package content is checked and compared with defined upper and lower tolerances in order to accept or discard the package. These tolerances are mandated, often in accordance with the e-mark legislation. If a package has a weight outside the tolerance, it is removed from the production line.
For both of these types, the check weighing process can be static (manual) or dynamic. In dynamic check weighing, the package will be moving along a conveyor belt or roller system. Therefore, the package’s static weight will be affected by the accelerations and vibrations occurring in the mechanical components of the conveyor.
Typical items that are check weighed for trade purposes:
- Big-bags (FIBC)
- Packaged meat and fish products
The advanced fluid damping properties of the T16 load cell will suppress the majority of such vibrations, allowing the static weight of the package to be accurately measured while it's in motion. The advantages of fluid damping within the T16 load cell for high speed applications are described in this Application Note.
Furthermore, the XT1000 and XT2000 weight transmitters are perfect for check weighing systems thanks to their high speed data acquisition rate, their advanced dynamic filtering and their dedicated check weighing software offered as standard.
Some check weighers are installed in environments where hygiene is critical; therefore they must be able to resist any potential damage from the wash-down of all surfaces using hot, high pressure water (or steam) on a daily basis. The X320 check weighing indicator is ideal for such applications, as it is manufactured from a high-tech food grade composite alloy that is better than metal at withstanding the large thermal gradients (and strains) that occur in the casing material during wash-down with hot, high pressure water. This composite alloy is chemical, temperature and impact resistant with a superior double O-ring seal. It is approved to OIML R76 and NTEP Class III/IIIL.
No matter what type of check weighing system you are designing, Thames Side can offer cost-optimised, reliable, repeatable load cells with the IP rating and level of precision to suit the application and high speed, dedicated check weighing electronics - all with the appropriate trade approvals.
Contact Thames Side now to discuss your requirements for load cells and electronics in check weighing applications.
We have the experience and applications knowledge to provide expert guidance on the optimum solution for you.