Electro-Pneumatic System in a 4.0 Context

The EB 80 is an electro-pneumatic system by Metal Work ideal in Industry 4.0 applications. This is possible thanks to the diagnostic functions, the ability to store large amounts of data and the possibility of interfacing with various fieldbuses

by Vittoria Ascari

Italian manufacturer of pneumatic components for over fifty years, Metal Work has developed the EB 80 electro-pneumatic system, which encompasses multi-pole or fieldbus- controlled solenoid valves and digital or analogue input or output signal modules.
In a pneumatic system, the EB 80 can be equipped with solenoid valves of different functions (2/2 NC, 3/2 NC and NO, 5/2 monostable and bistable and 5/3) with electrical or manual controls, connections with input fittings up to 12 mm in diameter and delivery fittings in the range of 4 to 8 mm in diameter, which will shortly be available also in 10 mm. The flow rate reaches 800 Nl/min in the version with an 8 pipe diameter and 1,200 Nl/min in the high-flow version with 10 pipes diameter.
In an electric system, all the modules can be controlled through the main fieldbuses available on the market,
IO-Link included. The maximum number of valve controls is 38 with a multipolar electrical connection and 128 with a fieldbus connection. Fieldbus-controlled signal modules can handle up to 336 signals (128 DI, 128 DO, 40 AI, 40 AO).Terminal board modules for digital inputs and outputs and thermocouple and thermal resistance reading modules are available too.

Maintenance and diagnostics

When developing a product, the greatest efforts for Metal Work are made to reducing the risk of failure through FMEA analysis, using the most advanced simulation tools and performing an innumerable sequence of laboratory and field tests.
Since the company is aware of the consequences due to downtimes for maintenance interventions, in the EB 80 it has developed a diagnostic system that keeps the island monitored and reports the faults in different ways. In all the versions, with a multi-pole or a fieldbus control system, a general error LED light is provided at the electrical connection module in addition to a signalling LED light on each valve. The LED system indicates any short-circuited, shut-off or missing solenoid valve, over voltage, low voltage and any interrupted transmission of the electrical signal. The presence of the fault is relayed to the island control system, which also indicates the type of fault in the case of a fieldbus connection.
Each base is equipped with a dedicated memory capable of collecting diagnostic and operating data (type of failure, number of cycles performed, duration of the activation time) of each valve, over a period of time that reaches fifty years of operation.

Replacing each faulty component without disassembling the island

Special care has been taken in the user interface in order to facilitate the operators’ work: all the information to be viewed and the objects on which to intervene are arranged on one side of the island: LED lights, pneumatic diagram, code, manual controls, customisable nameplate, fixing screws.
Each faulty component can be replaced without having to disassemble the island, just using a Phillips screwdriver, therefore not only for the valves but also for the fieldbus module and the input and output modules. For this reason, the EB 80 can offer not only an excellent “horizontal modularity” (i.e. the possibility of adding or removing valve bases and signal modules) but also a “vertical modularity” (i.e. removing elements vertically, without having to disassemble the valve island).

Collection of self-diagnosis data

The diagnostic functions, combined with the ability to store large amounts of data and the possibility of interfacing with various fieldbuses, make the EB 80 an optimal component for use in Industry 4.0 scenarios.
A typical application relates to the collection of self-diagnosis data, i.e. the behaviour of solenoid pilots mounted on the valves. The EB 80 processor collects the data, allocates them to the internal memory and transmit them to the external controller via fieldbus. These data can then be processed in the field or sent to specific in-house storage systems or remotely to a cloud server. This function is useful, for example, to monitor the system locally or from a company service centre located in another geographical area or even, at the user’s request, remotely via teleservice directly from Metal Work.

Control of a cylinder response times

Another smart function is the control of a cylinder response times. In fact, one of the typical uses of the island valves is the actuation of pneumatic cylinders, which usually come with proximity sensors that read the position of the piston. The digital signal sent by the sensors are read by EB 80 input modules, by closing a control ring of the cylinder itself. The island controls the movement of the cylinder and reads the signal associated with the movement. All this is done locally, without having to use the PLC.
In this way, the island can assess any cylinder activation delays over time due, for example, to failure, pipe clogging, piston seizure or other inconveniences. The reference activation time and the acceptability tolerance can be set. In case of variations, the system generates an error message that can be handled locally or remotely.

Cylinder speed control

Lately, another possible application is cylinder speed control. Similarly to the aforementioned function, the EB 80 can clearly control the movement of the cylinder on both directions and read the signals generated by the two limit switches. In this way, it can detect and monitor the average speed of the cylinder and the number of strokes performed.
The valve island is therefore able to record the distance covered and monitor any speed variations due, for instance, to changes in regulation, an increase in friction or changes in applied loads. The unexpected reduction in speed can cause a drop in productivity, while a sudden increase can cause the breakage of the actuators or the mechanical parts of the machine.
Also in this case, it is possible to enter a reference value for the speed and a relative acceptance tolerance. In case of unexpected changes, the system generates an error message to be handled by the operator. This is a local verification made in real time and directly in the field, without the need to develop further applications on the control system.