Finding the right control system to use in hostile manufacturing environments

While modern human-machine interfaces (HMIs) with clear graphical dashboards are considered the epitome of efficiency and ease-of-use; in certain situations, their usage can appear somewhat cumbersome, particularly in challenging and dusty manufacturing environments. This was the dilemma faced by NCS when installing a new control system for a walking beam furnace: what kind of HMI was desirable and considered fit-for-purpose in a hostile production setting?

With the team on the factory floor, who worked with heat treatments, required to wear protective gloves for the duration of a shift the use of modern HMI touchscreens was deemed unworkable.  The new system also had to offer operators the freedom to move around unimpeded i.e. give workers complete 360-degree mobility so they could raise and lower the beam furnace as well move it back and forth, and open and close its door.

After consultation with Underwoods, the industrial automation and control specialists, a remote push button station based on Siemens ACT with PROFINET quickly emerged as the most suitable system for the conditions. Not only was there an incredibly quick installation process that delivered cost and time advantages, the solution was also robust and durable with the highest ingress protection (IP) rating against dust, dirt and moisture – all the ideal components for heavy manufacturing use.

When designing the system, the location of the pushbutton station was to be sited some distance from the programmable logic controller (PLC).  Civil works for running underground cables were also to be avoided.

PROFINET is the leading Industrial Ethernet standard for automation. The openness and flexibility give users optimum freedom when designing machine and system structure.  Besides standard wiring, push buttons and signalling, devices can be connected directly to the controller in the field or cabinet via PROFINET, AS-Interface and IO-Link. This way, wiring time is reduced and error sources can be minimised, allowing more flexibility if future modifications are required. In NCS’ case, just one cable ran from the PLC to the PROFINET gateway with the pushbuttons wired from the gateway – it was simple, cost-effective and saved time.

The station featured 14 buttons including an e-stop – failsafe switch.  A couple of the devices had additional inputs and outputs with two of the digital inputs for limit switches on doors that, without the IO, would have had to have been wired back to the panel. A potentiometer was also wired into an analogue input as a speed control on some pumps.

The solution delivered the potential for up to 21 signalling devices and the pushbuttons and e-stop connected to Siemens’ Totally Integrated Automation (TIA) portal. The TIA portal provided instant feedback on cable faults with accurate diagnosis for fast resolution.  Tagging the system was simple and permitted the movement of buttons without rewiring as buttons were retagged within software. Siemens ET200 failsafe central processing unit (CPU) automatically triggered a failsafe warning in the event of a connection loss.

The benefits to NCS were significant – savings on cost and time were a direct result of the simplicity of the system and ease of installation. The build-time for the controller came in at 2-2.5 hours, including time to cut holes for the pushbuttons and wire the controller using a flat ribbon cable between devices. For the same number of pushbuttons using a different set-up a minimum of 35-core multicore cable, a screened cable fir the potentiometer, terminals, cables, ferrels, numbers, additional digital 16-way IO and analogue card would have been used. Siemens solution delivered an overall cost saving of approximately 50%.

For the future, NCS plans to use Sirius ACT with PROFINET wirelessly and looks forward to discovering other innovative solutions for its specialised manufacturing work in the most demanding of environments.