Load cell and A/D converter used in sack-filling machine

All-Fill International Ltd has selected HBM's PW12C 75kg capacity load cell and AD103C analogue-to-digital convertor (A/D) card for its latest sack-filling machine. This ensures that the accuracy of the machine meets the specification of +/-0.1 per cent of the fill weight. The machine is designed for filling 25kg sacks but All-Fill International decided it needed a bigger load cell to meet different customer specifications.

The PW12C is made from aluminium with a maximum platform size of 800 x 800mm and the load cell is available in a number of options to meet a wide range of requirements. The load cell has OIML R60 approval and has a six-wire configuration so that cable length can be altered without impairing measurement accuracy.

All-Fill International started designing the sack-filling machine a year ago and based the design around HBM's load cell specifications. Simon Goulden, All-Fill International's Engineering Manager, says: "We wanted a reliable load cell that was flexible enough to get the required accuracy but physically strong enough to support the weigh platform, as it needs to be quite robust in this application".

Options and accessories

The sack-filling machine is multi-functional and can include an additional 5kg-capacity load cell and various attachments such as platforms for filling pails and boxes in addition to sacks.

All Fill International has a long history of working with HBM and has used both its digital and analogue models. This includes using HBM's FIT1 digital load cells.

HBM's FIT1 digital load cell features integrated overload protection for service loading of 150 per cent of the maximum capacity to provide additional safety. The load cells are normally used in applications where speed and accuracy are crucial factors. Manufactured in stainless steel, the FIT1 digital load cell provides IP66 protection to meet All-Fill International's requirements.

All Fill International often works with OEMs and its machines are integrated into production lines with the machines usually in continuous use. Each machine is normally built individually to meet the customer's specifications. The company uses load cells in a variety of ways in its machines including the 'bulk-and-dribble' method where the auger can be run at high speeds for the main product fill and then at slow speed to top up the product. In this mode the accuracy of the machine is dependent on the reaction and settling time of the load cell.