CRNE pumps offer frequency control for delicate cooling lubricant system

FISBA OPTIK AG uses RumA centrifuges and Grundfos pumps

The company

Germany’s RumA Reinigungstechnik GmbH creates edge disc filters, candle filters and centrifuges that are used for the purification of cooling lubricants.

Centrifuges play a central role in the coolant lubricant process. Centrifuges are able to separate any type of liquid from any type of solid. If a system operator requires an especially high level of purity in the lubricating coolant – like with grinding, honing and lapping applications – centrifuges are used. The jewellery industry also uses centrifuges  to recover recyclable materials like gold or silver. Centrifuges have a high degree of separation efficiency (1800 to 3500 times gravitational acceleration) at large volume flows, which is useful when working with precious metals.

The challenge

FISBA OPTIK AG requires clean lubricating coolant for its glass-processing systems. The company creates lenses for industries like medical technology, semiconductors, industrial manufacturing, security and space travel. With the diameter of a pencil lead (0.5 mm), concave or convex grinding of such lenses on both sides is a challenge. To create flawless lenses, lubricant coolants must be available at a constant temperature and pressure level.

The Grundfos solution

Grundfos worked with RumA to design a system that provided FISBA OPTIK with a constant pressure of cooling fluid year-round. To begin with, RumA built a central cooling lubricant system that could supply FISBA OPTIK with up to 450 litres of cooling lubricant/min. This was

Photo: Every Grundfos lubricating coolant pump is supplied with a redundant standby pump. All plant systems were designed using stainless steel, as water is used as a coolant with little emulsion and a resulting low corrosion risk.

done with the help of three centrifuges, each of which separates 10 dm³ of solids from the cooling lubricant. The three levels of machine tools in FISBA OPTIK's new 4400 m² production building get their cooling lubricant from a 4,000-litre tank. Two frequency-regulated Grundfos CRNE pumps are on each floor and alternate automatically every 12 hours. Using constant pressure control, they maintain a supply pressure of 6 bar, present even at the final supply point – also when multiple machine tools demand cooling lubricant at the same time. The supply pipes, pumps and centrifuges were designed accordingly. Grundfos handled the calculation of pressure losses.

Customer benefits

Grundfos e-solution pumps offer an impressive coefficient of performance along with practical features:

- Individual adjustment to the required duty point

- Actuation via pressure, differential pressure, flow temperature sensors (0-10 V or 4-20 mA)

- Motor connection via plug & pump system

- Adjustable using remote operation R100.

E-pumps can easily be integrated into manufacturing processes in this way. Analogue and digital inputs enable individual actuation, e.g. as a function of tool magazine assignment.

The benefits of frequency-controlled CRNE pumps are obvious in FISBA's project.

"At most, all machine tools on a given floor will require around 150 litres of cooling lubricant per minute. The operating pump must be designed to meet this need,” says Andreas Huber, RumA Sales Manager. “Yet when fewer machine tools are in operation, the requirement decreases accordingly – and the pump automatically reduces its speed. What is important here is that the pump must still supply the same pressure."

RumA Managing Director Dipl.-Ing. (FH) Rudolf Hasenfratz left, Sales Manager Dipl.-Ing. (FH) Andreas Huber right.

Frequency control offers significant energy savings (reduced operating costs) along with a technological benefit: If the pump is running at reduced speed, there is less heat transfer to the cooling lubricant. This eliminates the need for a separate chiller.

The engineers at RumA often choose Grundfos pumps for the application of lubricating coolant circuits. The company has installed approximately 3,000 lubricating coolant supply systems worldwide. Since Grundfos offers service globally, the company was a natural choice for a partnership.

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