Safely conveying and metering corrosive media

To ensure that screws can withstand adverse environmental conditions over the long term, a durable surface is crucial. EJOT, a medium-sized group of companies in the metalworking industry and the European market leader in fastening technology, relies, among other things, on electroplating to coat its screws. Until now, to ensure reliable operation of the electroplating process at the plant in Bad Laasphe, the baths had to be regularly “refreshed”—that is, replenished—manually with new chemicals. Now, chemical-resistant magnetic centrifugal pumps with a dosing function simplify this step while improving both occupational safety and the process’s cost-effectiveness.

Complex Screw Finishing

Electrochemical metal deposition, also known as “galvanizing,” requires several steps to achieve the final result. In the electroplating shop at the Bad Laasphe plant, the screws first undergo various pretreatment stages: descaling, hot degreasing, and pickling. They are then further cleaned through electrolytic degreasing and stripping—that is, the neutralization of adhering acids or alkalis. For the actual electroplating process, they are then immersed in a zinc-acid or zinc-nickel plating bath. Each of the two plating baths has a volume of approximately 20,000 liters and over 15 coating stations. This is followed by heat treatment and post-treatment using a choice of four media to produce blue, thick-film, transparent, or black surfaces. The finishing process is then completed with a sealing or anti-seize coating applied to the surfaces.

Hermetically Sealed and Safe

The modular SAFETEC pump set from FLUX is used to safely dispense chemicals. It consists of magnetically coupled centrifugal pumps in a compact console with integrated leak monitoring. EJOT uses five different SAFETEC systems in the basement, each made of materials (ranging from PVC to ETFE) specifically matched to the various chemicals. The pumps deliver fluid at pressures of up to 1.3 bar and can safely handle fluids up to 60 °C. Each pump is connected to the appropriate container via a hose line and a dry coupling. The couplings reliably prevent the medium from leaking during connection or disconnection and eliminate any contact with the medium when changing containers. The containers are then emptied using the self-priming centrifugal pump via a suction lance. Depending on the container type, either a conventional IBC suction lance or the VARIBOX’s integrated suction lance is used for this purpose.

Thanks to its magnetic drive without a shaft seal, the pump itself is hermetically sealed and operates maintenance-free. A drip tray in the console is designed to collect any liquid resulting from potential leaks in pipes or fittings. For dosing, a non-contact ultrasonic flow meter—which operates without coming into contact with the media and is therefore wear-free—monitors the flow rate. The pump, console, and piping thus form a reliable delivery system with minimal maintenance requirements and low “lifecycle costs.”

The Right Pump Solution for Every Application

The modernization of chemical dosing in electroplating demonstrates how occupational safety, process reliability, and cost-effectiveness can be effectively combined. By using hermetically sealed pumps with automated dosing functions, screw-type electroplating achieves high reproducibility with reduced operational risks. In addition to the SAFETEC units used here, Flux also offers simpler models without a dosing function. Alongside the stationary systems, the pumps are also available as mobile units mounted on a cart, allowing them to be easily moved to the storage tank. Optional accessories, such as various dry-coupling systems and valves, complement the pump set to meet the specific needs of different applications. This tailor-made solution for the electroplating process has won over the screw manufacturer. The purchase of additional SAFETEC systems is planned for the future.