In recent times, manufacturers have begun to lay more focus on increased line production and minimum product loss. Consequently, the use of safe and efficient machinery has received far more importance than before and has led to a couple of breakthrough innovations in the machinery segment. 'Safe Motion' is one such innovative technology, which ensures workers safety and protection of equipment.
A machine safety measure in the traditional sense refers to add-on components that reduce the risk of harm to people, equipment or the environment that may arise from the operation of an individual piece of production machinery or line. Historically, safety control systems were made up of a series of safety relays with long strings of operator inputs or guard switches wired into the safety relays. Some of the machines used to have five or six of these safety relays, which led to a very complex wiring plan in order to ensure reliability and safety of the system. Besides, because of the long string of wiring to each individual device, miswiring was very common. Hence, for several years, application of the conventional machine safety measures was viewed as a cost burden, as they emphasised operator safety at the expense of productivity.
Today, with the development of technology, safety measures have become available directly in motion actuation devices, which are also known as Safe Motion. Moreover, safety functionality is now embedded in the actuators that are distributed throughout the machinery. As a result, only parts of the machine are stopped or even slowed down in the case of emergency. This has helped the machine to restart faster, without any need for repositioning of axes and reduced downtime. For instance, IndraDrive with safety on board developed by Bosch Rexroth AG features a safety solution that offers the packaging manufacturers not only operator safety, but also efficient equipment performance. IndraDrive with safety on board reduces line speed rather than a complete shutdown of the line when a safety-related incident is detected. Operators can also set up the machine or clear jams without risk, even while the machine is operating.
Growth driving factors
In the current scenario, industrial safety is receiving increasing attention from manufacturers, as an accident at work place can cause injury to workers (the most important component of any manufacturing plant), damage to material and machinery, production delays, fines, negative effect on company's image and environmental hazards. Hence, a number of manufacturers are demanding the safe motion technology, as it protects not only people, machine and environment, but also supports business benefits such as increased productivity and improved machine utilisation.
With the use of safe motion technology, manufacturers can now enjoy an immediate improvement in operator efficiency in the areas of production changeover, production set-up and intelligent diagnostics for maintenance. The use of integrated safety measures allow operators to perform tasks such as checking, changing tools, cleaning and aligning, which in the past could only be performed if the power were completely removed from the drives. The use of safe motion technology also provides benefits such as, retaining accuracy during repositioning, less break wear and faster recovery from faults, consequently increasing the productivity and machinery utilisation.
In addition to the end-users, the use of safe motion technology has benefited machinery manufacturers as well. Moreover, machine safety measures or safe motion technology has emerged as the fastest growing segment of the machinery industry. The use of safe motion technology in a drive has simplified the overall safety design, as it requires fewer sets of wires for each input (E-STOPs, contactors, or guard switch). With the simple wiring, there is less likelihood of miswiring. It has also enabled the machinery manufacturers to develop a flexible solution that can be employed in a wide range of applications, thus helping the machinery manufacturers to reduce the cost of design and installation.
Besides, drive-based safety solutions require fewer amounts of safety modules in the machine, thereby reducing the cost of design, layout, programming and commissioning. The technology has also allowed machinery manufacturers to reuse the safety solution from previous designs on each generation of machinery, as well as in a variety of machine product lines. Thus, the integrated safety measures have provided machinery manufacturers with a competitive advantage rather than a cost disadvantage.
Also, government regulations have played a key role in the growth of safe motion technology. The safety standards set by governments and other agencies have a dual purpose of reducing the risk of injury to machine operators to an acceptable limit as well as maximising the machine utilisation. Accordingly, the international safety standards, such as IEC 61508 (the international standard for electrical, electronic and programmable electronic safety related systems) and EN 954-1 (European standard for safety strategies) have laid guidelines for conducting risk assessment, thereby helping manufacturers produce safer and more productive machinery.
In addition, complying with these safety standards has helped machinery manufacturers to increase marketability of their products. Besides, ANSI/PMMI B155.1-2006, the safety standard governing the safety requirements for packaging machinery and packaging related converting machinery, was approved as an American National Standard in April 2006. According to this revised standard, both suppliers and users of packaging machinery are responsible for assessing and reducing risk to an acceptable level. The requirements of this standard apply to new, modified or rebuilt industrial and commercial machinery that performs packaging function for primary, secondary and tertiary packaging. This has also led to the growing adoption of safe motion technology in the packaging machinery industry.
Relevance of SMT in packaging industry
Recognising the benefits of safe motion technology, the adoption of integrated safety measures is catching up gradually in the packaging industry as well. Of late, the packaging machinery manufacturers have been using various safety measures such as safety drives, safety PLC and safety relays. Safety PLC and safety relays are the most widely used integrated safety devices. A safety PLC is a programmable logical controller designed for use in safety-related applications. Safety relays and contactors are used to carry out specific control functions such as emergency stops (E-STOPs), locking and interlocking, safety timers, light barriers etc. In recent times, the leading machinery manufacturers are focusing on development of safety relays that can be used to perform multiple safety functions. For example, Germany-based Pilz GmbH & Co KG has developed PILZ PNOZ, a complete range of stand alone and modular safety relays, which can be used for all safety functions, such as monitoring E-STOPs, safety gates, light barriers etc.
This apart, safety drives, which include servo drives and AC drives, have emerged as the most sophisticated motion control device for the packaging industry. A drive based safety system is preferred by the packaging manufacturers, as it provides for the faster response time than the conventional safety technology. The safety drive combines two-channel functionality with a dual-channel motor feedback device to provide a safe device. This helps the drive respond very fast to internal malfunction.
The food and beverages packaging industry is the major end-user of safety drives, as it provides for rapid changeover as well as flexibility for handling different products. For instance, SIG Asbofill GmbH, Germany-based aseptic bottle-filling machinery manufacturer, has used IndraDrive drives developed by Bosch Rexroth Corp in its ABF 610 bottle filler. ABF 610 baffle filler, the highly synchronized machine fills 100 ml to 750 ml plastic bottles with juices and dairy beverages at 25 cycles per minute. The machine has five functional units, and its 13 servo axes control the indexing mechanism, in-feed, out-feed, sterilization and capping stations. Some of the drives are fitted with Bosch Rexroths integrated safety technology, which allows the drives to monitor their own motion, rather than relying on external monitoring devices. Self-monitoring avoids the switching delays that are inherent in external monitoring systems. In addition, the ability to react quickly has permitted SIG Asbofill to design a safe mode that allows the operator to move freely inside the machine without disconnecting the power. Following this, the machine can continue production without time-consuming restart, recalibration or resynchronization routines.
The safe motion technology used in the bottle filler includes a lockout mode that holds the motor with or without torque, when the operator needs to enter a work area. Also, a safety Input/Output (I/O) allows crosschecks to prevent people from circumventing safety devices.
Also, in case of flexible packaging machinery such as pouch machinery that handles products like oat meal, drink mixes and soups, servo drives have distinct advantage over other hardwired safety devices. Servo drives not only provide precision motion, but in the event of a fault such as a web wrap orweb breakage, it also acts as the breaking mechanism, driving the machine to stop as quickly as possible.
Further, with the technological development, the application of various software-based safety systems and robotics is growing as well. The software-based safety system offers a variety of safety solutions, apart from remembers machine position even if the work is moved to clear the jam. This enables operator to clear the jam and get the system back to full operation in much lesser time than is required by a conventional system.
This apart, an increasing number of packaging manufacturers have started using robotics for various applications, including palletizing and depalletizing. This has helped the packaging manufacturers to reduce accidents occurring from falling loads, sudden movement of jammed pallets that are freed etc. Further, Packaging Machinery Manufacturers Institute (PMMI), in association with Robotics Industries Association has introduced the new PackSafe 4 software to identify potential hazards and provide methods for elimination of these hazards. The new software includes the risk matrices for robotics applications, packaging applications and machine tool applications.
Way ahead
Overall, the future of safe motion technology in the packaging industry seems bright. The demand for safe motion technology is expected to witness rapid growth across sectors. The global market for machine safeguarding solutions was worth US $1.5 billion in 2006, and is expected to grow at an annual rate of 12.5 per cent over the next five years, to reach approximately US $2.8 billion in 2011. This impressive growth in the global market for safe motion solutions is mainly attributed to the rising demand for certified, automated safety solutions instead of the obsolete hardwired safety products in all end-use sectors. Also, the growing affordability of integrated safety solutions coupled with increased flexibility enabled by the technological development is driving the growth of safe motion technology. China, Japan and India are expected to be the key markets for the safe motion solutions in the near future.
(Courtesy: ITC Bulletin)