Safety and protection against tampering from Euchner
Lockout/tagout system ensures safe maintenance processes and saves energy
Accident cause analysis and accident avoidance: Awareness for safety is increasing in the manufacturing sectors around the world. Maintenance and servicing tasks play an important role here. As long as a person is in the installation, its standstill must be guaranteed. Safety solutions as commonly used in the USA, Australia and New Zealand, for example, disconnect the entire installation from the mains for this purpose, resulting in a long, energy-intensive restart phase. Euchner GmbH + Co. KG in Leinfelden near Stuttgart has developed a versatile lockout/tagout system that permits much more efficient maintenance processes. The voltage is not switched off, and the installation is therefore not only ready for operation again much more quickly; it is even possible to stop only an affected sub-section while the remaining units continue to run.
This customized system has already proven its worth and is now being used on around one-third of the machines at Gerhard Schubert GmbH, a specialist for top-loading packaging machines (TLM). More machines will follow.
By law, the machinery directive prescribes a risk assessment and the evaluation of the respective safety requirement for an installation. The assessment and evaluation are based on the international standard ISO 12100 or the machine-specific C-standards. They result in qualitative requirements for the safety circuits, supplemented by detailed national occupational safety and health, such as the OSHA (Occupational Safety and Health Association) standards in the USA. "A certain safety risk results for each installation based on the analyses. With our integrated safety systems, we help to minimize the risk while ensuring the highest efficiency possible. This allows us to achieve the highest safety level, namely Performance Level e," emphasizes Stefan Euchner, Managing Partner of Euchner GmbH + Co. KG.
Manufacturers are liable for the safety of their machines
With the traditional lockout/tagout system, the operator or service technician must affix his personal lock at a central location to prevent anyone else from switching on the machine. This system is particularly widespread in Anglo-American countries, where companies use it to shield themselves against claims for damages involving high compensation amounts - an aspect that is becoming more important all the time in view of declining training standards of machine operators in these countries.
Schubert, the market leader for top-loading packaging machines, has also been receiving more and more requests for lockout/tagout systems in recent years. "Although the Plexiglas safety doors provide a good view into our packaging machines, large units or installations inside can always conceal some areas," says Siegfried Rottler, Control Engineering Team Leader at Schubert in Crailsheim. "In the worst-case scenario, somebody inside the machine could be overlooked and injured. This could lead to high claims for damages against a company."
As a machine manufacturer, Schubert is contractually obligated to guarantee the safety of its machines. However, the experts at Schubert often were not convinced about the reliability of systems proposed by customers in the past. The loss of productivity was another factor. On a machine subject to one malfunction per hour, traditional systems reduce the production efficiency by around three percent. This is due to the fact that with traditional lockout/tagout systems, the electrical voltage is switched off to prevent the machine from starting up during the maintenance process. If the machine has to be restarted afterwards, the associated production downtime can be as long as 30 minutes.
CKS - Coded Key System - safe, efficient and networked
Siegfried Rottler from Schubert and Managing Director Ralf Schubert went searching for an alternative to the traditional lockout/tagout system with padlock. They chose a system from safety engineering expert Euchner, with which they have already had contacts over many years. Its solution is named CKS - Coded Key System. Unique electronic keys transmit their data to a key adapter without contact. All keys are inserted during production. After the machine stops and before opening a safety door, operators and service technicians can reliably protect themselves by taking one of the keys. The machine can be switched on only when all previously removed keys are in their key adapter again.
Euchner supplemented the CKS with an integrated AS-i Safety at Work interface especially for Schubert. ASi stands for "actuator-sensor interface" and designates a system for efficient interconnection of actuators and sensors via a standard bus system. This allows machine states and feedback via the sensor system to the control system to be polled. In the Schubert example, a ring circuit is installed in the installation and linked to the control system in order to connect the sensor to the bus system. As a substitute for separate wiring of each component, this system saves work and expense while providing maximum safety.
Euchner increases protection against tampering
The CKS is an RFID system with electronic coding options. It is based on transponder technology involving wireless transmission of the incoming signals. The system employs induction to produce a voltage field, which is transmitted to the key. A coil installed in the key allows the system to exchange the code sent by radio waves with the key. The CKS detects that the correct key, i.e. the only key that was previously taught for the system, is inserted based on the unique code.
A CKS not only dispenses with the 30-minute production downtime, but also increases safety compared to traditional lockout/tagout systems with a lock. The reason: no duplicate is possible with the CKS. Keys to traditional lock systems generally can be duplicated. They can be lost or can be copied without permission. Companies therefore have to take precautions to prevent a key with the same number from appearing. Conventional lock systems can therefore provide the same level of safety as the CKS from Euchner only with great organizational effort. By contrast, the CKS requires each electronic key to be "taught in" at its place of use. In other words, each key is unique. The unique code ensures that there is no duplicate of the electronic key anywhere in the world. When a new key is taught in for the system, the previously used key becomes invalid. Consequently, the possibilities for impermissible tampering are very limited.
"We can recommend the CKS without reservations"
Lockout/tagout systems are already installed in around 30 percent of the TLM machines at Schubert, and the trend is clearly rising. The systems are prefabricated by Euchner, and Schubert adapts them to the particular characteristics of each machine. As measured by a 30-minute downtime after each maintenance process, the expenses for the adaptation soon pay for themselves. "Out of all the lockout/tagout systems available on the market, we feel that the CKS is the best option for guaranteeing the safety of operating personnel and protecting against potential cases of damage," explains Rottler. "As Euchner developed it in accordance with the requirements of our customers in various countries, Schubert can recommend it without reservations. The higher productivity is an additional argument in favor of using the CKS."
Versatile use in all industries
Das Lockout-Tagout-System von Euchner ist weltweit in den verschiedensten Industriezweigen im Einsatz. Dies liegt nicht zuletzt auch daran, dass es ganz unterschiedliche Aufgaben lösen kann. Beispielsweise ist mit ihm - im Gegensatz zur Verwendung bei Schubert - auch eine gezielte Zuschaltung einzelner Einheiten zum Produktionsprozess möglich. In dieser Rolle stellt es sicher, dass nur dazu berechtigte Personen die Maschineneinstellungen verändern können. "Von der Arbeits- über die Prozess- bis hin zur Manipulationssicherheit - unser Lockout-Tagout-System überzeugt aufgaben- und branchenübergreifend", erklärt Stefan Euchner. "Und lässt sich flexibel und individuell an die Anforderungen der Kunden anpassen."
About the EUCHNER GmbH + Co. KG
The lockout/tagout system from Euchner is being used in diverse branches of industry around the world. This is due not in the least to the fact that it can solve diverse tasks. For example, unlike how it is used at Schubert, it can also be used to permit targeted activation of individual units for the production process. In this function, it ensures that only authorized personnel can change the machine settings. "From occupational safety and health, through process reliability to protection against tampering - our lockout/tagout system delivers a convincing performance in all tasks and industries," explains Stefan Euchner. "And it can be flexibly and individually adapted to suit customer requirements."