Study of a collaborative palletising system for the end of line in the food sector

The goal of this project is to verify the feasibility of robotic palletising. The case study concerns the end-of-line process for a food sector company specializing in poultry distribution.

Currently, operators take boxes from a roller conveyor and manually palletize them onto four pallets arranged in a rectangular matrix downstream of the roller conveyor. Up to twelve boxes must be stacked vertically on each pallet.

The purpose of this study is to verify the possibility of automating the process while meeting the following requirements:

• The automation must be able to handle two different logics:

  • Tight sequence palletising, where the boxes are stacked vertically, completing one column at a time;

  • Wide sequence palletising, where the boxes are arranged horizontally, completing one layer at a time;

• The four pallets must be palletised simultaneously;

• The gripping system must be able to handle boxes of different sizes and weights;

• Cycle time: 400 boxes/hour;

• Use of collaborative robots due to the lack of space for installing containment barriers and guards;

• The space available for automation is very restricted due to the need to cool the environment: 

  • length 2600 mm; 

  • width 2600 mm; 

  • height 2650 mm.

The project output is required to include:

• The layout of the robotic station defining the model of collaborative robot;

• The design of the gripping system;

• The simulation of the application (necessary to verify the reachability of all points and to program the palletising logic);

• The experimental validation of the solution through prototypes

The "box-like" geometry of the boxes prevents the use of vacuum systems for gripping. Therefore, the gripping will be managed with a parallel gripper equipped with fingers thin enough to slip between boxes during palletising. The gripping system was designed with the support of SCHUNK Intec.

The main advantage of using pneumatic technology is the weight and cost savings compared to an electric device of the same size.

The PHL 40 has a variable closing force between 435 and 1,300 N, depending on the supply pressure, ranging from 2 to 8 bar. To increase the friction force, a layer of rubber was placed between the gripper fingers and the boxes.

To satisfy the requirements, the FANUC CR-35iB robot was selected: with an equal reach compared to other cobots, the CR 35 has a payload of up to 35 kg, which allows it to move two boxes without exceeding the load diagram limit.

The simulation, carried out with the Roboguide software, shows that the robot is capable of palletising up to 480 boxes per hour by picking up two boxes at a time from the roller conveyor. The highest point reached by the robot is 2,554 mm from the ground. Therefore, there is a margin of 96 mm between the robot and the ceiling.

The results of the simulations in terms of the number of boxes palletised per hour and the effectiveness of the gripping system were experimentally validated during tests conducted on a prototype of the robotic station. The entire automation process was recreated in the i-Labs Industry laboratory, replicating the layout studied in the simulation, including the arrangement of pallets and the roller conveyor. Regarding the gripping force, it was adjusted by varying the supply pressure of the gripper until achieving the optimal closing force, sufficient to maintain the grip during all phases of movement but not so high as to bend or damage the boxes. The tests also confirmed the simulation results in terms of reachability and the number of boxes palletised per hour.

Altesia operates as an innovation manager on behalf of major companies in the food industry, focusing particularly on logistics applications and the management of industrial processes. 

Taking into account the constraints given by both customer and food industry, the research process followed for this EDIh4Marche service allowed the creation of a fully functional prototype. Collaborative robot FANUC CR-35iB robot, equipped with Schunk PHL-40 gripper, was at the heart of the automation process: the robot was programmed to pick up and palletise open boxes of varying sizes and weights on pallets in a condensed layout, while remaining below the ceiling level.

Tests performed at i-Labs Industry on the constructed robotic station showed, in fact, that the developed solution is capable of meeting the requirements in terms of space compactness, handling of open boxes, and cycle time. Moreover, challenges presented by the station logic were also overcome, with robot routines allowing flexibility in terms of palletising sequences. Such routines could be easily modified and adapted to meet eventual additional requirements.

The robotic station can therefore be proposed to producers and distributors of fresh foods in order to automate the palletisation of pallets, thereby increasing process efficiency and relieving human operators currently employed in this strenuous task. An increased efficiency, as well as productivity, while maintaining the product quality offered so far, can also be converted into lower labor costs and, consequently, increased profits.