Two automatic machines, manufactured by Atom MB, carry out the roughing and cementing operations on the shoes of a well-known global producer of high-end footwear. In front of these, two six-axis robots from Mitsubishi Electric take care of tending activities, in full autonomy and without physical barriers, thanks to their sophisticated safety options. The modular cell, already working at the customer’s premises, combines modularity and flexibility with the capability to process 750 pairs of shoes per day.
by Fabrizio Dalle Nogare
Relieving the operator of repetitive tasks with very low added value, thus reducing the risk of error and increasing both repeatability and efficiency of the production process. This sentence, which perhaps encloses the very essence of process automation, may sometimes turn into quite an empty refrain. In fact, proven skills, innovation spirit, constant application, ability to choose the right partners, experimentation are all qualities needed to make such a sentence concrete in industry. Certainly, these requirements are not within everyone’s reach.
Eng. Sergio Dulio, Chief Innovation Officer at Atom and great expert in technology for the footwear sector, has followed the highly innovative project since the very beginning. He tells us about the project itself at the company’s headquarters in Vigevano. “The automated RAMS (Robot Assisted Manufacturing System) is the result of a collaboration that began more than two years ago between AtomLab and a well-known German manufacturer of high-end footwear. We started, together with the customer, by identifying the operations with lower added value within the cell. I’m basically talking about machine tending activities. We decided to entrust these operations to the robots.
The two production machines remain the system’s key element: compared to the stand-alone version, there is little change, at the moment, from a mechanical point of view, while we have changed quite a lot on the software in order to make communication with the robots easier”.
Machines do the work, robots feed them
Talking about the cell we were able to see, the system consists of two machines and two robots. As requested by the customer, a palletized transfer line was also created.
The shoes are loaded manually on a support, made with 3D printing and resulting from careful and thorough research, so as to adapt to different models in terms of size and height and not risk causing damage to the shoe. In the first of the two islands, a six-axis Mitsubishi Electric robot with 13 kg payload picks up the shoe and places it inside a CD10 roughing machine made by Atom MB, a subsidiary of the Atom Group. Here, two operations take place: pre- roughing one and a sort of fine- roughing, in preparation for cementing.
The machine, which is fully automatic, has a double work station for processing two shoes (one pair) at the same time. Once the operation has been completed, the robot places the shoe onto a rotary table equipped with a clamping system, specifically designed to make the grip as repeatable as possible. The second six-axis robot picks up the shoe from the rotary table and places it inside the cementing machine, namely a CD3 machine made by Atom MB, where the actual cementing operation takes place in quite a short time thanks to the use of an innovative solvent that requires a very short drying time. At the end of the process, the robot places the shoe directly on the pallet, from which the operator picks it up for the following operation, namely its joining with the sole.
The three laws of footwear robotics
The cycle of the robotic cell developed by Atom is only apparently simple. Behind its realization, as Mr Dulio tells us, there are years of research and tests. “Each cell produces 750 pairs of shoes per day. The complete installation is made of two twin cells, with 1500 pairs overall. The RAMS respects what we like to consider – half joking – as the three laws of footwear robotics: modularity, safety and flexibility”.
What is it about? It’s early on said. “Each element is a stand-alone module, part of a ‘plug & play’ system designed to become, in the near future, easily reconfigurable not only from a mechanical point of view, but also in terms of software. Safety is really important because – without using physical barriers, but thanks to systems such as laser scanners – operators must be able to access the cell, without taking risks, at any time”. The third element, flexibility, deserves a special mention. “The line is designed to process shoe models with different size, shape, height and geometry”, explains Sergio Dulio. “Handling is absolutely central and, in order to achieve our goals, we have designed a special gripper, able not only to adapt to all the geometries, but also to guarantee a given reliability and, above all, not to damage the shoe during gripping operations: it is not at all easy to harmonize all these aspects without affecting throughput. The gripper also makes it possible to use the ordinary show shapes and not the special ones, thus reducing significantly the cost barrier for automation”.
Cooperative robots in full safety
These requirements perfectly fit with the idea of robotic automation that Mitsubishi Electric is pursuing. “Our customers are mainly interested in the cooperative use of traditional robots. To do so – says Gianluca Annunziata, Senior Project Engineer Factory Automation Division at Mitsubishi Electric – we install the MELFA Safe Plus device, allowing the operator to interact with the robots safely and without barriers. In this cell, each of the two robots is equipped with two Datalogic laser scanners to cover entirely the surrounding area, divided into two sectors: the entrance to the first one causes the robot to slow down at a certified speed of 250 mm/sec, the same as that reached by collaborative robots. If the operator comes any closer, the robot stops. It is enough for the operator to leave these two areas for the system to restart, automatically and without any instructions from the operator itself”. In terms of automation architecture, Mitsubishi Electric’s IE Field CC-Link bus manages the acquisition of signals from the machine.
The system is a multi-CPU one: a PLC Safety and the two robot CPUs coexist on the same rack. Due to this architecture, they use the same anti-collision system.“The two Q-Series RV-13FRL robots with Safety option, in addition to ensuring high accuracy and speed, have internal wiring and integrated motors, thus making movements in applications with limited space easier” adds Mr Annunziata.
A starting point
The synergy with a partner such as Mitsubishi Electric has certainly made the design of the line easier, as Sergio Dulio states. “The modularity of the control solutions and the direct communication between the PLC and the CPUs of the robots have been very important elements in order to achieve our goals, as well as the system that manages the interaction between the two machines and the two robots, which work in tight spaces. For these reasons, the reach and the wrist payload are the two features on which we have most focused our attention”. The impression we have when we look closely at the robotic cell is that we are in front of a starting point for further developments to be pursued by pushing the opportunities offered by automation in shoe manufacturing. In short, there is room to test further innovation. “We are seeing increasing interest in this type of machine, both in Europe and elsewhere, for example in the Far East”, says Atom’s Chief Innovation Officer. “Boosting efficiency through automatic shoe handling or having more repeatable and controllable processes are very interesting options for manufacturers working in several segments of the footwear industry”.