Check weigher is music to their ears

The CD has revolutionised our lives, from replacing good old vinyl to providing a cheap, reliable, high capacity computer storage medium. Most customer complaints today centre around buying incomplete packages where the CD is missing. You try convincing your retailer that the CD was missing from the package, and see how far you get.

For Nimbus Manufacturing finding a way to minimise this annoying problem was of paramount importance. Manually checking daily the 100,000 plus CDs packed was labour intensive and not 100% effective. Nimbus turned to a local bespoke weighing and control applications company, Balance Systems, for a solution.

To meet the specific requirements Balance Systems decided to develop a special version of its existing check weigher which met the cost and setup criteria.

A typical CD package weighs around 100g, made up of the outer case at about 80g, the disc at 10g and the printed insert at about 2g. Due to the manufacturing tolerances, the finished weight of the complete package can vary by as much as +/-1g. And the weighing system had to be capable of detecting a missing printed insert.

The check weigher developed consists of a motorised conveyor belt and electronic control unit. At the heart of the weigher is a strain gauge load cell which converts the weight of the package into an accurate electrical output. The load cell has to support the belt conveyor and drive motor which weighs over 7kg. Conventional load cells struggle to provide the resolution to detect the required fine tolerances of a few grams above this dead load. The Model 9010 load cell has been developed for these applications and features an adjustable `tare back-off’ facility to counter balance the weight of the conveyor. The system can weigh effectively at speeds of up to 100 packages per minute.

DCG Associates 01562 638800