XTS in a variable system for producing multi-component plastic dowels
Achieving an increase in output rate of more than 30% on almost the same footprint requires sophisticated assembly processes and high-end automation. This is why fischer Innomation has opted for the performance and precision of Beckhoff XTS and motion control, supplemented by a wide variety of I/O components, for a new system for the fully automatic assembly, labeling, and packaging of multi-component plastic dowels.
A spin-off of the fischer Group’s custom machine building division, fischer Innomation in Horb am Neckar has decades of expertise in the construction of assembly and production systems.
True to its history, the machine builder’s focus is on fully automated assembly systems for a wide range of plastic dowels and the production of steel dowels, which are then assembled and packaged. Assembly and filling systems for cartridges that are filled with two-component adhesives or other chemical products, for example, represent its third area of expertise. Generally, the machine concepts support material infeed through printing and packaging and finally palletizing.
“As a matter of principle, we design all systems on a modular basis so that we can provide a flexible response to customer requirements. Although changes to requirements as early as the design and assembly stages are relatively rare, they are inevitable after the first few years, so that the systems can support the production of new products,” explains Alexander Schäfer, head of control technology, software, and electrical design at fischer Innomation. “And the greater the bandwidth of technologies and functions, the more important a scalable and flexible automation platform like PC-based control becomes,” adds Dieter Völkle from the Beckhoff sales team in Balingen. This is particularly evident in the latest project, a fully automated production system for multi-component plastic dowels. “The system represents a milestone in terms of managing complexity and optimizing the process of previous production lines,” points out Eckhard Bukenberger, division manager at fischer Innomation.
XTS is opening up optimization potential
The specifications for the new system were ambitious: Flexibility and output were to be significantly higher on a similar footprint: “Around a third more output compared to the existing systems,” explains Alexander Schäfer. Not an easy task with around 250 dowel variants, most of which are produced, packaged, and prepared for dispatch on a make-to-order basis. “When changing products, we must be able to make all settings without manual adjustments,” says Eckhard Bukenberger, describing another key requirement. Market requirements are constantly evolving, and with them the demand for multi-component plastic dowels. This inevitably leads to adjustments to the assembly process. With XTS and the various software tools, fischer Innomation can now reconfigure the system as required. “Achieving significantly reduced set-up times compared to the previous automatic assembly machines,” emphasizes Alexander Schäfer.
The assembly concept was implemented with PC-based control on an XTS track approximately 10 m in length with 48 movers, which link the individual process stations for the assembly of the multi-component plastic dowels. On the first station, the basic component of the multi-component dowel is inserted into the brackets of a mover. A product-specific label is then applied by two CO2 lasers. Due to the high power, both lasers are controlled via Safety over EtherCAT (FSoE).
Optimized processes through variable mover grouping
Compliance with the short cycle time requires using two of the slow laser stations (double the previous number) in the system, with one product now being moved towards each station at the same time. Reducing cycle times by implementing slow processes several times and supplying components simultaneously is a key feature of the XTS. This duplication of the process stations is possible because each mover can be controlled individually and does not have to follow a fixed sequence. Each mover represents an axis in TwinCAT and can be controlled individually using various functions. “This means that the components placed in the movers can be grouped and positioned as required – without the movers being mechanically locked in place,” says Dieter Völkle, highlighting an important feature of XTS. TwinCAT NC actively controls the mover positions even at standstill and keeps the dowels in position.
Both features come into play in subsequent process steps, where the movers are positioned in groups of 6 under six parallel stations and precisely fixed by energizing the motor modules. “Precisely means with 0.1 mm accuracy,” Eckhard Bukenberger points out. On the way to the removal and packing station, the dowels on the movers are swiveled 90° at full speed via a guide rail. This means that they arrive at the grippers with the correct orientation. This detail saves fischer Innomation an additional swivel axis on the grippers of the SCARA robots. Groups of 4 are again ideal for removing and setting down the dowels.
From simulation to finished program
XTS simulation mode was incredibly helpful when planning and validating the system concept. For example, the simulation showed that the most effective way to achieve the increase in throughput was with 48 movers and six parallel press-in stations. “Being able to set up and interlink all process steps with such flexibility with XTS was what convinced us,” says Eckhard Bukenberger. The XTS was delivered as a pre-assembled and tested functional assembly, including a control cabinet, and integrated into the machine in Horb. “All we had to do was install the software created with the simulation tool and we were able to get started almost immediately,” recalls Alexander Schäfer.
The position data calculated and coordinated by TwinCAT based on the setting patterns is sent to the robots in the removal and packaging unit via EtherCAT. “Rather than just dropping the dowels into the box, we specify the insertion depth and the horizontal offset for each layer,” explains Alexander Schäfer. The setting patterns are part of the parts list for an order. The data is stored in a central database on the production controller and can be retrieved by the machine operator via OPC UA and the TwinCAT Database Server.
Consistently decentralized and modular
The control architecture is also designed according to the principle of maximum flexibility. “Thanks to the wide range of infrastructure components for EtherCAT, fischer Innomation can set up the network in the same way as the process stations and expand it as required,” Dieter Völkle points out. Each feed unit has its own control cabinet, which is connected to the control computer (a C6032 ultra-compact Industrial PC) via star distributors. The palletizer is integrated via an EL6695 EtherCAT bridge terminal, for example. fischer Innomation connects the sensors and actuators for the process stations via EP and EPP Box modules.
“On the basis of our positive experiences, EtherCAT P is our preferred standardized cabling concept for our special machines,” says Alexander Schäfer. On the control side, there are plans to replace the existing visualization with TwinCAT HMI, as well as to integrate more robot variants. Additional space will be saved in the control cabinet by converting the drive technology from AX5000 compact servo drives to the AX8000 multi-axis servo system. “We can use the know-how gained from this project for external projects in the future and recommend the use of XTS without reservation,” concludes Eckhard Bukenberger.
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