How one sensor ensures correct packaging of a beloved breakfast staple
In the food industry, packaging for transport is one of the most important production steps since intact delivery of products cuts costs and ensures revenue. In the Finnish Arla dairy factory, SICK 3D vision ensures the quality control of products. A single intelligent sensor is sufficient to ensure the correct packaging of each yogurt container that passes through the packaging line.
One of the many products Arla produces is yogurt. Each container is packaged in boxes of six and then loaded onto a pallet for transport. However, in an effort to increase sustainability, the use of plastic in the packaging of yogurt had to be reduced. Instead of plastic boxes for transport, they are now using cardboard, posing other issues.
However, the adhesive of the cardboard box would sometimes fail on the production line. A ruptured box will not hold the yogurt containers in place and an incorrectly filled box is a loss of profit for Arla. Occasionally, one of the six yogurt containers in a box was missing.
Ensuring quality of every cardboard box
“On the packaging line, the production system has a small blind spot so the operator of the machine cannot see the boxes properly,” said Janne Nickström, production coordinator at Arla.
A single defective box is already a problem. It was clear that every packaged box would need to be measured, analyzed, and then accepted or rejected.
Arla turned to PJ Control, a supplier of automation solutions, to jointly search for a suitable technical solution. It turns out that the shape of a correctly loaded, intact yogurt box is consistent and clear to make it easy to measure and analyze its three-dimensional shape. The perfect choice for this task: the TriSpector1000 3D vision sensor from SICK.
Configurable, intuitive, and reliable 3D inspection of moving parts
The TriSpector1000 creates a three-dimensional model of the entire packaged yogurt box while it is being transported on the conveyor belt. The measurement accuracy of this 3D vision camera is very high, in practice down to the millimeter. But, even the best sensor is useless, if it doesn't provide relevant information for automation.
When packaging yogurt, not only is the accurate visualization of the three-dimensional box important, but also information about whether the box is intact and able to be stacked on the pallet.
A useful feature of the TriSpector1000 is the intelligence integrated into the sensor. The sensor housing contains an adaptive logic that makes industrial image processing possible.
During commissioning, the sensor is taught the correct, acceptable shape of the yogurt box by feeding it images of intact objects. The 3D vision sensor on the production line now tirelessly and repeatedly measures the boxes. The acceptable boxes are allowed to continue their way to the pallet, the rejected ones are sorted out of the line.
The solution in Arla's factory is also special because a significant improvement in production quality was achieved using only a single sensor and associated equipment
“Thanks to the functioning sensor inspection, we are saving a couple of work hours per week,” Nickström said.
Switching sizes at the press of a button
The software product for controlling the operation of the sensor is the SOPAS Engineering Tool from SICK. It is easy to use, and Arla was able to independently configure additional functions on the sensor. It is possible, for example, to package two types of yogurt pots on the packaging line, both flat and tall ones.
The two types of product boxes can be selected with the press of a button. If the shape of the yogurt boxes is changed at some time, it is easy to teach the sensor the shape of a new acceptable box. No replacement of the sensor or extensive upgrade project is required.
“The ability to configure the functioning of the sensor ourselves is important to us,” Nickström said. SICK is also satisfied with the end result.
“Arla’s project is a fantastic example of how the productivity of an existing production line can be increased through a modest investment in automation. Thanks to the saving of a couple of work hours per week, the investment will pay for itself remarkably quickly,” said Olli Korpinen, area sales manager at SICK in Finland.
