Manufacturing automation is now well into the Industry 4.0 era. New machine control and drive technologies are rapidly being introduced to provide more flexibility and productivity as well as smarter, more sophisticated use of real-time, actionable data on machine performance.
The same advances in digital electronics and automation software are powering flexible and effective new concepts in safety technology for automation. Complete machine safety platforms are now being offered that provide easier programming and greater versatility in the safety functions they support. These new platforms are more compact to save valuable space in control cabinets yet provide significantly faster response times to enable safety systems to deliver the necessary protection with the pace of today’s automation systems.
One key advantage these new safety platforms offer is scalability. They can be deployed as drive-based systems or can easily be scaled up via software to become a complete safety control solution — one that is tailored to a manufacturer’s individual requirements with maximum flexibility and protection.
Safety Technology Follows Automation Trends
Automatic safety features — such as emergency stops, safety curtains, or door interlocks — are designed to protect people and machines when problems occur or when operators need to enter machine spaces where they could be at risk. Safety drives and PLCs dedicated to responding to these devices have improved to address the rising sophistication of automation platforms.
A key trend in recent years has been the growth of high-speed safety buses, following similar growth of high-speed Ethernet-based automation buses. There are multiple safety bus architectures available that are supported by most safety drive and control device suppliers: CIP Safety on Sercos, Failsafe over EtherCAT®, PROFIsafe on PROFINET, and CIP Safety over EtherNet/IP™.
Use of these high-speed safety networks, which operate as a standalone layer apart from the main automation bus, has increased as more safety devices are being tied directly to them, rather than being separately hardwired via I/O directly to machine controllers.
These high-speed networks also support faster response times for safety drives and controls. This is necessary because drive technology has advanced considerably. In addition, today’s linear and servo motors are engineered to operate with much faster cycle times than in the past.
Therefore, to ensure safety within much shorter actuation trigger times, machine designers must either reduce automation sequence speeds or protect people by ensuring a greater safety clearance from machine movements. For example, safety equipment such as light curtains is installed further away from the process, which means the machines take up more floor space. However, users are demanding not only safe but also smaller machine footprints.
Leading drive and control suppliers are responding to these trends with safety technology capable of reducing reaction times to as little as five milliseconds. As a result, equipment manufacturers can make machine movements much more dynamic to improve productivity without sacrificing safety. At the same time, the distance between people and machines can be reduced without hazards. This saves floor space and fulfills another end user requirement.
In addition, since more safety devices now have bus interfaces and are connected via a high-speed intelligent safety bus, diagnostics and predictive maintenance are improved. By being on the network, it’s much easier to identify if a device is malfunctioning, rather than having to troubleshoot a network of interconnected devices.
Choosing Safety Platforms
The wide range of safety control platforms available today presents a challenge for both automation OEMs and end users. Most automation system providers can state that they comply (to one degree or another) with industry standards for machine safety devices; the differences that need to be assessed are how those platforms are designed to provide machine builders and end users with more flexibility in the context of their machine designs to maximize safety, automation efficiency, and machine costs.
It’s important to consider innovative safety platforms that are engineered for scalability, providing machine builders with options to suit specific machine requirements. These platforms start with drive-based safety technology that does not necessarily require the cost and complexity of a more complex PLC-based solution but that can still be scaled up to a complete safety control system while staying within the same family of products.
In addition, be sure to assess the features and functionality of drive-integrated safety systems. While some might offer only five or six safety functions, more robust solutions will offer a full menu of 20 to 25 functions, all of which are easily programmable using graphical interfaces that do not require specialized programming skills. This provides important flexibility: if a specific section of a machine needs a safety function such as Safe Torque Off (STO) with quick reaction time onboard, a full-featured drive platform will support it via software selection, without additional hardware or software required.
If the application demands safe movements in accordance with the safety integrity levels SIL2 and SIL3, developers can easily add that capability with no need for extra space. Certified functions for safe positions and safe speeds can also be selected. Because this full range of functions is available on the drive level, there is no need for manufacturers to program the control system.
More Safety in Tighter Spaces
An ongoing challenge for many manufacturing operations is to control the footprint of the automation system including minimizing the amount of factory floor space used for control cabinets. The latest generation of drive-based safety systems can help keep the cost and complexity of control cabinets to a minimum, because they utilize the latest generation of digital chips and space-conscious design to pack more performance into compact units.
For less complex automation platforms, this means it’s possible to use safety drives to support all necessary safety functions, reducing costs by eliminating the need for a safety controller. If, however, a machine’s design is more complex with additional points of I/O and safety functions to support at one time, that same platform can scale up to incorporate PLC-based safety control. The safety functions are still resident in the drives but the PLC manages the drives, rather than wiring all the light curtains and other safety devices to each drive.
The latest generation of safety drives and controls is scalable enough, in both hardware and software, to support the full range of safety requirements of today’s production and material transport systems. Furthermore, choosing safety technology from one family with common hardware, software, and programming tools makes it easier for end user manufacturers to manage their safety controls platform.
There are also platforms that are scalable in the way their drives can be networked. Simpler systems can have safety signals from light curtains and other devices delivered right into the drive via local I/O. On more complex machines, there are more connectivity options such as using the safety bus.
Newest Safety Technology Delivers Flexible Solutions
Today’s leading safety drive and control platforms provide the vital protection of people and machines that has always been an essential part of automated manufacturing. The most valuable solutions combine compact, space-saving dimensions with ultra-fast response times, ease of programming and commissioning, and scalable options.
From cost-effective, drive-integrated systems that support a full menu of safety functions, to complete safety control systems that efficiently combine drive-based and PLC-based controls, machine builders and end users now have more flexible choices that can fully align with their Industry 4.0 operating environments.
This article was written by Tim Loria, Product Manager at Bosch Rexroth, Hoffman Estates, IL. For more information, visit here .