When Groupe Danone’s Domino, the biggest biscuit producer and market leader in Finland, needed to improve process control reliability, it turned to ABB general machinery drives with high dosing accuracy.

One of the two AC drives controls the screw conveyors that dose and sift the flour and sugar needed for making the filling for the Domino brand. The screw conveyors dose the powdery ingredients onto the scales; dosing accuracy is the critical requirement. The PLC supplies the start and stop signals and speed selection commands to the drive, but the acceleration and deceleration ramps and speed references set in the drive are necessary for achieving the required dosing accuracy.

At the beginning, the dosing is rough, and the screw rotates at a high speed. When the automation system detects the weight on the scale is approaching to the target, around 10kg less than the quantity specified in the recipe, for example, the drive’s reference value is reduced. The screw then starts to rotate at a slower rate to enable more accurate dosing.

“We make 150 to 200kg of filling at a time. We aim for maximum dosing accuracy, although certain margins are acceptable depending on the product, as with sugar, for example,” says Ari Ylitalo, LU Finland engineering supervisor.

The other ABB general machinery drive is the main drive at the filling machine. “This is a critical application, and the ABB drive does a good job in controlling the key process of our flagship brand,” says Ylitalo. The controlled motor is a 2.2 kW, 400V ABB induction motor, with a speed of 1,430rpm.

Jani Suominen, LU Finland operations director, stresses reliability is the quality the company values most when choosing the drives. “The production lines with all their conveyors are hundreds of meters long, and the ovens alone measure some 60 to 80 meters. The conveyors involve a great number of moving parts, and we cannot afford to compromise our production by using equipment that doesn’t meet our requirement for 100 percent reliability.”