Rather than a burden, a white paper from Schneider Electric looks at how the embedded technology used to meet changing machine building regulations and safety compliance has improved productivity.  Safety was considered an additional cost to bear in an increasingly competitive market. Something OEMs and operators had to address, but so reactively. They would implement the minimum automated safety functionality to meet the regulations.

Safety delivers  better machine performance

However, that approach been replaced with the view that safety functionality goes beyond safeguarding people and protecting machinery. Today, machine process companies have seen how safety enhancements lead to better machine performance and improved overall production.

Although safety and productivity may at first glance seem mutually exclusive: safety calls for machines to shut down if there is an abnormal condition that presents a danger to operators, whereas productivity requires machines to keep running. In other words, safety demands downtime but productivity demands uptime. However, the embedded safety functionality new generations of variable speed drives and servo drives can safeguard operators while simultaneously minimising the amount of time the production line is shut down.

EMBEDDED SAFETY

Embedded safety drives integrate safety functions that control the drive output to the electrical motor in response to safety-related events. These functions can either stop the drive without shutting off power to the motor entirely, or control the speed of the drive. It means a drive does not have to ‘wait’ for a signal that there is an abnormal condition (e.g., overspeed, blockage).

A simple example may illustrate how adopting embedded safety drives can improve operator safety while at the same time boosting productivity. In a woodworking machine that uses a spindle to shape the material, stop ramps (Safe Stop 1, for instance) can be used to precisely manage operator access, for example, clear away chips from the spindle shaft. As cutting power to a big machine can take several minutes to stop its spindle, there is always the risk that operator will try to interact with the machine before the cutter heads stop spinning.

Stop ramps avoid operators waiting longer than required by rapidly stopping the machine, ensuring that any damage is limited and that operators can quickly assess problems in a safe environment (STO). The drive with embedded safety functionality cuts off the torque on the motor but does not shut off power altogether, enabling faster start-up. Downtime and potentially costly damage are reduced, and operator safety is not compromised.

OPERATOR SAFETY

When operators are near the moving parts of the machine, Safe Limited Speed allows them to inspect, perform basic maintenance, or remove blockages without shutting the machine down completely. This safety function allows the operators to quickly assess and resolve problems, improving machine uptime and more efficiently managing the production line. The ability of operators to manage machinery through embedded safety drive functionality also reduces the requirement to employ specialist electrical engineers, who would normally be needed to take the machine off-line and restart.

Embedded safety drives also reduce the amount of waste that normally occurs if a component or machine fails or needs to be inspected. The Safe Limited Speed function allows individual machine or component problems to be quickly evaluated and resolved, so less material upstream of the production line needs to be scrapped.

Download a copy of the white paper How Embedded Safety Drives and Networked Safety Cut Costs and Boost Productivity from 999 Automation