Detecting, interpreting, communicating: Smart Sensors for intelligent packaging machines

Smart packaging – the use of active and intelligent packaging is growth and future trend offering huge potential, writes Marco Kaiser, strategic industry manager for consumer goods – packaging in the Factory Automation Global Industry Center at SICK.

The networking of the physical and digital worlds using smart packaging also has a direct impact on the machines that produce packaging and package products. This is reflected, for example, in the increasing use of intelligent sensors that can communicate in packaging machines. The portfolio of Smart Sensor Solutions from SICK is actively paving the way for increased flexibility, transparency, efficiency, quality, and availability.

To achieve all of this, a wide range of real-time information is required directly from the machine. Intelligent sensors which collect data, interpret it, generate information from it, and then communicate this, are in a position to enhance this valuable data and to use it to create effective packaging machines and high-performance packaging processes. With its Smart Sensor portfolio, however, SICK goes even further and uses the intelligence of the sensors for additional Smart Task functionalities which can be used to carry out different checking and automation functions directly in the sensor. Examples include the adjustment of switching thresholds when detecting contrast marks or transparent films and containers, the automated activation of object, format, or configuration-related detection profiles, or the automated differentiation of objects, object edges, and gaps in a material flow. Logic functions integrated into the sensors for processing signals form the basis of this, building on proven sensor technologies with best-in-class detection capabilities. These make it possible to carry out defined tasks autonomously and remotely, meaning that automation systems and networks of packaging machines can be relieved effectively in the case of edge computing.

What sets Smart Sensors apart?

Sensors are generally the sensory organs of machines – in the context of digitised manufacturing, they are also the initial contact with and link to Industry 4.0. Whereas the aim in the past was to simply collect data and make simple decisions, today’s sensor intelligence also enables data to be prepared, further processed, and interpreted. Sensors therefore no longer just “sense”. Within the scope of digitisation, they are also starting to “think”. As a result, sensors convert data into valuable information. The intelligence of these Smart Sensors is supplemented on the one hand by the option to communicate this information. In other words, they can exchange information with the control of a packaging machine or a cloud-based application. On the other hand, these sensors are capable of completing defined tasks autonomously – in the form of the Smart Task functionalities that have already been mentioned.

Sensor intelligence supports the commissioning and condition monitoring of packaging machines

The advantages offered by the intelligence of Smart Sensors and their communication capabilities are a recurring theme throughout the entire life cycle of packaging machines. Various parameter settings can be visualised, tested, and optimised from the integration and initial commissioning of the sensors in the machine – on the device as well as via the control. What’s more, various sensor parameter sets can be stored here on an order-specific or format-specific basis and loaded to the Smart Sensor during operation. This option enables flexible settings to be made for any number of sensors simultaneously by downloading parameters directly from the control, such as the sensing distance, hysteresis, or switching threshold. This saves time, eliminates errors, and means that the settings can be documented at any time. At the same time, this makes the packaging machine so intelligent that products, product variants, or packaging formats can be changed autonomously, quickly, and reliably.

The Smart Sensors perform permanent condition monitoring autonomously while the packaging machines are operating. Alongside this, they also keep an eye on the packaging process and provide information in real time on whether there is a functional impairment or whether one is to be expected, as well as on whether maintenance may be required (predictive maintenance). This enables the service intervals of the packaging machine to be optimised in line with the cycle – and therefore intelligently – for example by using scheduled machine downtime as an opportunity to carry out sensor cleaning or maintenance. 

Smart Sensors provide added value that packs a punch

Intelligent sensors which are able to communicate offer key properties and therefore advantages for packaging machines right from the outset. They also become smart – and that is the unique selling point of Smart Sensor Solutions from SICK – as a result of the logic functions integrated directly into the sensors for processing signals. Depending on the requirement and task, the advantages of Smart Sensors for packaging technology can cover up to four areas: Enhanced Sensing, Efficient Communication, Diagnostics, and Smart Tasks.

The Enhanced Sensing feature of the Smart Sensor Solutions provides extra detection performance if required. The contrast sensors from SICK’s KTS, KTX, and KTM product families offer dynamic adjustment of the switching threshold. This enables even faded print marks and optical markings to be detected quickly and reliably. As a result, processes such as the correct positioning of packaging material, the perforation or folding of the packaging at the right point, or the control of table top inserters are becoming much more powerful and reliable – improving the productivity of the packaging machine. When producing bottles, different product variants are often conveyed in the same system. These must be reliably detected and counted in the flow of bottles to enable them to be transferred smoothly to a packaging machine, for example. The challenge for the sensor comes from the huge differences that are found in the shape and surface of the bottles – i.e., their optical appearance. Photoelectric sensors such as the WL12-G, the W4-3 Inox, or the WLG16 with ClearSens technology are Smart Sensors which are able to master tasks of this nature, as they offer the option of storing bottle-specific sensor settings as pre-defined detection profiles and retrieving them automatically to match the bottle variant. This means that the sensors always work with the optimum parameterisation, ensuring maximum detection reliability. Shiny and reflective packaging also requires particular detection capabilities as it reflects the sensor’s light back in different directions – which can lead to switching errors when using conventional sensors. In contrast, photoelectric sensors such as the W16 with their TwinEye-Technology achieve the highest levels of operational safety as detection is carried out using two logically linked receivers in the sensor. The sensor only switches to the output state when both “eyes” come to the same evaluation.

Efficient Communication is the second feature of Smart Sensors and comes into play with the digital transmission of analog values. It is based on the bidirectional IO-Link communication standard and is carried out via standard M12 cables in parallel to the usual IO communication in the packaging machine. Smart Sensors such as the WTT12L Powerprox enable individual sensor parameter sets for different packaging formats or configurations to be loaded into the control via IO-Link during commissioning and then stored there. During operation, they are then loaded via IO-Link into the sensor to match the relevant secondary packaging. As a result, the connectivity of Smart Sensors opens up intelligent and – again and again – new possibilities for enhancing the productivity of packaging machines. At the same time, the sensors deliver important process information via the communication interface which can be used for statistical purposes, documentation, cloud applications, or visualisation on stationary and mobile devices – which is where the area of Diagnostics comes in. 

The Diagnostics functionality of the Smart Sensors – which would be virtually unthinkable without its communication capability – is used first of all for the purposes of self-monitoring. On top of this, the sensors check the quality and reliability of their signals independently. In digitised packaging processes, diagnostics functions also provide the possibility to significantly improve the availability of packaging machines through condition monitoring. A welcome “side effect” for the machine manufacturer is the fact that the sensors provide the edge data and additional function at no additional cost and enable it to be used in the machine itself as well as in the cloud – for example for big-data-based predictive maintenance applications.

The smart WLG4SC-3 photoelectric sensor is also capable of monitoring itself autonomously. To do this, it evaluates its signal strength and any changes that may have occurred due to deposits forming, and uses its AutoAdapt function to adjust the switching threshold dynamically in response to the gradual contamination of the optical surfaces of the sensor. From the perspective of the packager, this too is an intelligent machine function which significantly extends the cleaning cycles, increases availability, and reduces service costs. In addition, cleaning and maintenance work can be scheduled in such a way that it does not have any negative impact on the productivity of the packaging machine.

The decentralised computing power of Smart Sensors, combined with their flexible programmability, lays the foundation for a multitude of Smart Tasks, which make the packaging machines even more flexible, dynamic, and efficient. When using the “Object and Gap Monitor” Smart Task, objects and gaps can be detected and measured within the sensor. The Smart Sensor only sends corresponding signals to the control if there are deviations from set target values – otherwise, there will be “radio silence” that protects the network between the sensor and the automation system. At the same time, the connectivity of the intelligent sensor offers the option to directly control an actuator using its signal delay and buffering functions and thereby to manage the removal process autonomously – without having to go via the control and the network.

These and further functions can be carried out independently by Smart-Task-enabled, intelligent sensors. They are also able to network with other sensors or actuators directly to resolve partial applications relating to edge computing autonomously, quickly, efficiently, and cost-effectively without extensive PLC communication.

Smart Sensors: more efficiency thanks to autonomous action

Intelligence and communication capabilities – on the one hand, the potential of Smart Sensors is oriented toward gradual increases in efficiency for the tasks at hand, such as downloading parameters for fast changeover, easy device replacement, formula management, and condition monitoring. Smart Tasks raise the value of these sensors to a whole new level – with their remote intelligence, they are able to generate new, higher-quality detection information, network, and carry out defined Smart Tasks autonomously. All of this makes SICK’s Smart Sensor Solutions a highly forward-facing technology for the packaging industry – enabling users to overcome the challenge posed by digitised packaging processes in a technically and economically efficient manner.