Protecting Both Man and Machine with PROFIsafe

When the safety of both employees and workpieces counts, the Polish company ADAL Sp. Z. o.o. implements the compact fieldbus module MVK Metal Safety in its new paint shops.

Nowadays it’s not very difficult to design an automated paint shop. The challenge lies in designing one that meets customer expectations, while at the same time complying with all safety regulations. Recently, the company ADAL Sp. z o.o. was able to successfully meet these needs by using Murrelektronik safety products in a paint shop in South West Poland.

Paint shops are typically made up of many different machines such as conveyors, lifts, handling stations, automated gantries, technical process applications for chemical preparation of produced items, powder or/and wet coating areas, as well as ovens for heat treatment.

Customer expectations for both the process and functionality of the application set the bar high, and complexity for this project was particularly high. The paint shop can be configured to coat three different groups of item widths and two different heating periods in the oven. Additionally, there are several types of processed materials (mild steel, galvanized steel, aluminum, cast iron), two types of surface preparation (realized in a 14-tub spray/immersion washer), three types of coating techniques (cataphoretic coating, powder coating, and a mix of both), and a wide range of powder colors and priority modes for express orders.

Despite a high level of automation, human supervision is needed to operate and control individual processing cells. For example, several times a day a technician takes samples directly from a tub, while automated gantries carry metal items over his head. The operator must check if the automated cleaning of a powder coating chamber is done properly. Such situations are very dangerous for both the technicians and the workpieces. Adding to the complexity, the process cannot be stopped or paused for too long because the coated parts could get damaged or become useless.

This complexity calls for a reliable fieldbus module that allows ADAL to successfully complete the project while prioritizing safety. The control units used in the paint shop are S7-1500 PLCs (one of them being an F-PLC). All of the devices are using PROFINET, which due to PROFIsafe, allows the combination of standard and safety components in one network.

Because of the large extent of the installation (almost 100x60m) and the high distribution of safety signals, ADAL decided to use MVK Metal Safety modules for safety I/Os. The variety of sensors used in the application was diverse, ranging from safety mats, limit switches, guard-locks, light curtains, to e-stop buttons. Murrelektronik’s MVK Metal Safety allows all of the sensors to be easily connected and implemented. Safety outputs are mainly used to stop the drives and cut off air pressure, and several types of SEW Eurodrive distributed drives were used in the project. The STO (Safe Torque Off) inputs of the drives were used, or a safe stop SS1 was realized depending on the type of operation of the drive. Implementation of MVK Safety modules enabled ADAL to control all of the signals, consolidate the amount of hardware used, reduce wiring and installation costs -especially when compared to IP20 solutions. ADAL also needed to maintain high safety levels PL d and PL e, which is not a problem.

Another interesting aspect of this application is that MVK Safety modules were additionally used in automated gantries controlled over wireless communication. Both control and safety information are transferred over Wi-Fi and there was no need to build a separate system for safety signals.