One-Stop Chocolate Production New production line makes full use of optimization potential At first glance, a chocolate candy would appear to be no more than a simple product. Things get more complicated when it comes to the high-tech processes and modern automation concepts used to make it – but the processing lines involved hold immense potential. The decentralized servo drive IndraDrive Mi minimizes the number of components in the control cabine “In order to best position ourselves in the marketplace, we’ve focused on manufacturing modularly-designed, customer-specific machinery that combines the latest technology and economic efficiency,” explains Valter Francesconi, Electronic Department Manager of the Molding Division at Tecnosweet, a young company from San Damiano d’Asti in Italy. “This approach makes it possible for us to be fast, dynamic and versatile.” Tecnosweet is part of the ACMA Group, one of the international market leaders in the field of packaging machinery who specializes in the development and construction of ready-for-use plants for food and packaging. That primarily includes molding facilities for chocolate; buffer, conveyor and distribution plants; robot cells for secondary packaging processing; and plants for primary packaging, such as horizontal tubular bag machines. Modular, customer-tailored design: this approach is reflected in Tecnosweet’s new processing line for chocolate products that comprises every process step from the cast product to final packaging. Tecnosweet’s new molding plant for chocolate is modularly designed throughout From liquid to solid chocolate As a drive and control specialist, Bosch Rexroth provides the entire spectrum of automation components for the molding facility, thereby contributing to the development of an efficient production line with minimal space requirements. The plant consists of a series of machines and devices in a row. The chocolate is first melted in heated tanks before being moved on to the pouring station, where it is poured into the recesses of a mold. At that point, the molds have been warmed with infrared rays at an individual station to give them the temperature they need when the chocolate is poured into the molds. A vertical shaking motion ensures that the chocolate is distributed equally throughout the recesses. The molds then spend around 30-40 minutes cooling; the temperatures vary depending on the type of product. At the end of the process, the molds are turned over and transported to the emptying station. The chocolate pieces fall onto a conveyor belt in rows and are grabbed by a buffer, an automatic mount that allows for a continuous flow of products to the packaging lines. This ensures uninterrupted production in the case that problems occur at the end of the line. The empty molds then return to their starting point, where a visual system inspects whether the molds still contain any chocolate residue. If a mold is dirty, it is removed and automatically replaced with a clean one. The cycle then begins anew. Automation solution saves space and wires Tecnosweet’s automation concept is as modular as the machinery it uses. The concept is based on Rexroth’s IndraMotion for Packaging platform. The motion logic control, IndraMotion MLC, takes care of the overall molding plant, including both motion sequences as well as the machine’s logic functions. The control also synchronizes the 30 servomotors with the decentralized drive system from the IndraDrive Mi series. This drive system combines control electronics and servomotors into one single unit; the drives are located directly on the motor. “IndraDrive Mi met all of our performance and reliability standards. That allowed us to realize our philosophy, which is based on modularity, across the board,” summarizes Francesconi. The decentralized structure allows for a minimized number of electric drive components in the control cabinet: as compared to the six meters otherwise required in similar situations, this one less than two meters wide. In addition, input and output units, such as sensor technology and switches, were directly connected to the IndraDrive Mi, thereby dramatically reducing the wiring inside the machine. And keeping in the sense of modularization, the optional scrapping unit with vision system was made independent using a L10 series mini-PLC from Rexroth. Tecnosweet was able to meet the customer’s demands – smaller control cabinets, less wiring and no external PLC – with that automation concept: a machine with streamlined, versatile architecture, 90% less space and 30% less wiring. “Conventional machinery involves hundreds of wires,” explains Francesconi. “This plant uses significantly fewer: one power supply cable, a hybrid cable for decentralized drives and SERCOS-based synchronization, and additional field bus cables for communication via PROFIBUS, secure data via SafetyBUS and for standard Ethernet.” For example, the electronic display panel is also connected to the Ethernet cable, which has the ability to display an alarm to the user, even from far away. The Ethernet connection can also be used as a radio link for industrial use via an access point. Rexroth technology transports the molds from one station to the next Flexible cam profile design IndraMotion MLC combines an SPS with a motion and robot control system and is based on the CoDeSys run-time system to allow an open, integrated control architecture. The control system is IEC 61131-3-conform and meets PLCopen international standards. “That basis allowed us to create particularly well-structured, easy-to-use software that can be tailored to individual customer needs through the use of function blocks,” adds Francesconi. One key element is the versatility that IndraMotion MLC offers for the development of cam profiles. This includes the options to choose between drive cams with data points, control cams based on motion laws and the innovative Rexroth FlexProfile software feature that allows the flexible creation of control cams. FlexProfile is based on the modularization of a complete motion sequence. Individual motion steps are described via an analytic motion law or support point tables and can either be related to a master axis or a time reference. Sequential segments can be dynamically adapted to the limiting conditions within the combination of master axis or time reference. External events, such as the position of a second axis or a failure event, can be specified as conditions for the start or interruption of individual motion steps. The result is a high degree of flexibility with a minimal amount of programming. But Tecnosweet is breaking new ground when it comes to mechanics, too. A new, patented, mechanical and chainless transport solution contributes to the line’s performance. Tecnosweet’s mold facility is only one of a handful worldwide where molds are transported without a chain, thereby eliminating the typical problems associated with plate link chains, such as lack of precision, fouling, non-linear progression, deceleration, or extension. The chainless system is powered by Rexroth automation solutions. Tecnosweet’s processing line involves a range of technical innovation – and all for a product like chocolate that looks so straightforward at first glance. Author: Hans Michael Krause Business Development Automation for Food, Packaging, Printing Industry Bosch Rexroth AG