A game-changing machine safety solution

13 June 2022

When Mills CNC designed its new SYNERGi Premier flexible robots cells it needed to ensure that it was compliant with safety requirements to support the relatively high degree of human interaction required for the cells.

Successfully integrating network safety to support collaborative working was essential to enable productivity and maximum uptime, while being completely transparent for the user.

“Using network safety from SICK helped us ensure successful integration. Without it, the project could have been more difficult, and more costly, if not completely prohibitive to implement, “ explained Chris Ingham, control and system engineer at Mills CNC. “With automated machine tending systems, the key objective is to keep the robot going for production efficiency, while having the flexibility to change the parts in and out. Automation should never make life harder for our customers. It should always make it easier. To protect and enhance the benefits of the flexible cell concept, the safety system had to minimise machine downtime and become second nature – almost invisible – to operators.”

The robot cells have a two-way loading/unloading station with five automated drawers. Even at this increased level of automation, operator involvement is inevitable to interact with the robot that continuously feeds the machine. 

Operator interaction
Working outside the cell, operators need to load up workpieces and remove machined components through the two-way automated drawers. Meanwhile, the robot operates continuously inside the cell, taking workpieces out of the drawers and feeding the machine, before replacing the machined component back into the drawer. Setters also need to enter the robot cell periodically to service the machine tool itself.

The cells employ the latest SICK safety hardware. Each of the five automated drawers is fitted with a SICK safety interlock with guard locking and a safety laser scanner is positioned at the foot of the robot to allow safe access for setters into the machine cell. 

At the heart of the safety concept is the SICK EFI-Pro network technology which supports direct integration of the sensors and the robot controls via Ethernet/IP CIP Safety up to SIL3/PLe. The Safe EFI-Pro system is SICK’s safety network for industrial automation. Based on the CIP Safety protocol, it enables safe communication between SICK devices and sensors, in addition to third-party CIP-Safety devices like robot controllers, through the safety controller and a the EFI-Pro gateway. The EFI-Pro system also enables full remote diagnostics so that the system’s performance is recorded and monitored.

“The number one challenge for us was finding a system that could talk natively, using the same protocols as the robot,” said Ingham. “Without the direct connection through the SICK EFI-Pro system over a single Ethernet cable, integration would have been much more difficult, and more costly.

“The interlock interacts directly with the control architecture of the robot cell system via CIP Safety. The system enables me to draw three-dimensional boxes around the drawer catches to restrict the movement of the robot and ensure clearance for the operator.”

Mills CNC opted to use the 9m range safety laser scanner using SICK Safe HDDM multiple scanning technology to control safe access for setters into the cell. The safety system enables the scanner to be used as the primary safety device with two protective fields to slow the robot down before it enters a full stop.

Simultaneous protective monitoring of multiple fields means less switching between monitoring cases, so dynamic protective fields can be shorter, and therefore more responsive and efficient.  

“Implementing SICK’s network safety has been a game-changer for us in bringing the machines to market,” concluded Ingham. “Less sophisticated systems would have required a complete shutdown whenever the robot and operator inhabited the same space, requiring a reset and restart. They would have also required complex wiring that could have been difficult, if not impossible, to implement.”

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