Croatian polyethylene film manufacturer explores factory-floor logistics automation
Muraplast of Croatia is the leading producer of extruded polyethylene tubular blow film (LDPE) in the southeastern European region. The company participated in an L4MS (Logistics for Manufacturing SMEs) experiment to improve the intra-factory handling and weighing of the heavy product rolls and at the same time, counter occupational health risks of its personnel.
Muraplast has an annual production capacity of 20,000 tonnes of LDPE polyethylene film that is mainly used for the packaging of beverages and food as well as in other industrial applications. Muraplast also produces industrial bags, pallet covers, sacks and a wide selection of plastic carrier bags.
What needed to be achieved?
The production process includes several human-performed steps, such as transporting the product rolls to a weighing station, reading and recording the roll weight, quality assurance and transferring the measured rolls into packaging.
In the machines, the product is wound around a shaft weighing around 50 kg, while the finished rolls have a weight of 40 to 500 kg. Safety standards stipulate avoidance of manual work involving weights above 30 kg.
The manual process steps are prone to human error, for example in reading the weight correctly. The several handling stages also present an occupational health risk as the weight of the products exceeds the recommended safety limits.
Therefore, Muraplast wanted to explore the automation of its logistics workflow to improve the speed of product transfers and the accuracy of weighing while at the same time mitigating the risk of occupational hazards.
Virtualised factory combined with real-life trials
The experiment consisted of two parts, first, a simulation of the factory, and second, a small real-life factory model on the premises of Innovation Centre Nikola Tesla (ICENT) for applied research and development in engineering and related applications. ASTI (Automatismos y Sistemas de Transporte Interno), an international engineering firm and producer of mobile robots, helped create the 3D factory model with Visual Components.
ICENT Robotics team demonstrated the prototype of Automated Guided Vechicle (AGV) solution, that was tailored for Muraplast
In the first part of the experiment, a virtual model of the factory (digital twin) was created in simulation software. The virtual factory comprised the entire manufacturing area with machines for extrusion, printing and cutting. Three transfer robots were virtualised for transport between 7 locations: raw material, extrusion (roll production), printing, cutting, weighing, roll packaging and finished product storage.
In the second part, a small factory model of the production area was constructed at ICENT. The model consisted of a location representing the machine with the ready PE roll that needs to be weighed and transported and a location representing the packing station where the roll needs to be unloaded. The experiment included an omnidirectional mobile robot built by ICENT for the purpose, and a roll sample.
Tests of the actual motion of the robots and interactions with them, as well as interactions with the Industrial IoT platform OPIL (Open Platform for Innovations in Logistics) that controls the workflow, were performed and the results presented to the company.
Some issues appeared during the execution of the experiment which were not obvious at the beginning of the study. The distances between locations are so short that the robot mostly stands idle. A human worker needs to be present for quality control of the printed rolls, so robots would not accelerate the production. At the beginning of the experiment, the plan was to use robots and industrial manipulators attached to the machines to pick up the heavy roll and mount it on the AGV. However, since there not enough free space around the machines, there are currently no robot-ready solutions to mount the rolls automatically.
The results showed that robots can handle and transport goods without predefined routes, but the problem of the heavy lifting was still not solved. During the experiment, however, Muraplast installed industrial manipulators and mobile manipulators with a core gripper. Furthermore, the factory plans to implement automatic measuring of the roll weights directly on the machines and connect machine data to its Enterprise Resource Planning system (SCADA). This removes the weighing of the roll and several other operations of machine operators, such as maintaining a production diary, writing the weight of roll on the label and manual ERP input.
Even though the experiment established that robots are not the optimum solution for the case, the overall benefits from the experiment were removing the weighing step from the production process and using roll manipulators to reduce the occupational health hazard. Valuable insights were also gained into the requirements of an optimal robotised factory environment and the IT systems necessary for automated logistics operations.
- How to accelerate production logistics
- How to automate product handling
- How to reduce occupational health risk
- IT system design
- Factory layout design through virtualisation
- Equipment testing and live simulation
- Insights into production design
- Increased understanding of requirements for automation
- Process development
Partners in the L4MS Experiment
System integrator creating the 3D simulation of the factory
Competence center resposible of testing OPIL using a mobile robot in a pilot environment