FACHAUX - Fruit grading machine

The purpose of the machine is to automatically sort fruit by weight bands. Each fruit is placed on a dish which files past at high speed on a rail. Without interruption, the system must precisely measure the weight of the fruit or vegetable and eject it into the required section.

• Grading rate of 5 to 12 per second, according to the type of fruit
• Weighing precision: +/- 1 g to +/- 5 g according to the type of fruit

SCAIME offered a solution in collaboration with Schneider Electric:

• An M238 PLC manages the overall control system.
• The weighing system is composed of an AQ single point load cell with a capacity of 15 kg, combined with an Enod3-C weighing controller equipped with application software for on-the-fly weighing.
• The eNod3-C oversees detection of the presence of fruit on the weighing section, measurement acquisition at very high speed (up to 800 measurements/sec), digital filtering and calculation of the weight of the fruit.
• At the end of the weighing process, the eNod3-C controller sends the fruit weight value to the PLC, which ejects it into the appropriate section.

This architecture optimises the system’s performance/cost ratio, since each device  performs the tasks at which it is most effective:

• The eNod3-C processes the signal and controls the on-the-fly weighing operation.
• The PLC controls conveyance and ejection of the fruits.
• Communication is facilitated by use of the CANopen interface between eNod3-C and the PLC.

In this way, the system reaches the desired maximum rate of 12 fruits per second with a precision level of +/- 1 g.