How does sustainability affect cooling lubricants?

Who thinks of sustainability when they think of cooling lubricants? If anything, other parameters often come to mind. Nevertheless, a coolant developer and manufacturer has taken on the topic. What initially starts as a thought quickly becomes a structured project of the heart, which those responsible pursue meticulously and with great care. Not only are the goals ambitious, but the results of the sustainability project are also conclusive. Companies from demanding and authoritative industries welcome the path to sustainability.

Sustainability is the most important megatrend of this decade. For sustainable development, the UN has defined 17 goals, so-called Sustainable Development Goals (SDG) (see info box). These goals

cover three dimensions of development, namely: economy, ecology, and social justice. Broken down to production processes, the question of sustainability therefore also arises in connection with the manufacture of components by forming or machining.

Consider products and processes equally

The responsible cooling lubricant manufacturer, Oemeta Chemische Werke GmbH, from Uetersen near Hamburg, set out many years ago to define, classify and take into account sustainability aspects when using machining media for forming or machining. The owner-managed, medium-sized company certainly deserves a pioneering role. This is evident because companies from authoritative and demanding sectors such as aviation, medical technology, electronics and the automotive industry welcome this.

Exactly what does that mean? The long-established company developed a mineral oil-free ester-based high-performance machining lubricant as early as the 1980s and has always been conscious about the environmental compatibility of its products. However, it is not only about products, but also about the processes in which they are used.

UN goals, Kyoto Protocol structure and push Due to the structuring by the UN Sustainable Development Goals, and by the milestone in the international cooperation, the Kyoto Protocol is a key factor in the expansion of sustainable development.

It can be assumed that eventually the planning and implementation of production processes will not be possible without a sustainability check. Thus, the sustainability question also arises for the production of components by machining. How can production processes be designed sustainably? Which SDGs can be addressed and pursued in the machining process chain? And which assessment standards can be used for this purpose?

First, sustainability strategies for users of machining media will be presented, then practical examples show how sustainability aspects can be considered within the framework of strategies in the machining process chain. At Oemeta, for example, SDGs 3, 6, 12 and 13 are used for the context of cooling lubricants. For the transformation of the EU economy for a sustainable future, the EU Green Deal is used as an action plan and thus focuses on climate and environmental protection.

  • Promoting a more efficient use of resources through the transition to a clean and circular economy
  • Restoring biodiversity and tackling pollution with the main objective of zero net greenhouse gas emissions in the EU by 2050.

The lubricant industry is following this path with the Sustainable Lubricants initiative. All stakeholders in the supply chain, as well as industry associations such as the German Lubricants Industry Association (VSI), politics and NGOs are to be integrated in the solution finding process to achieve maximum acceptance.

Changed process design and modern products score points

The process design alone can make an important contribution to the sustainability of a machining processes. If it can be designed in an energy-optimised and resource-saving way, this can have strong sustainability effects. For example, closed-loop processes, in-process recycling, and systems for de-oiling chips can recover used and dragged-out machining media. Here, it is also the responsibility of the coolant manufacturer to not only provide its products, but also to advise accordingly and to appeal to the decisiveness and determination of those responsible for the process. If the design of the process chain is adapted, this can relieve the environment and reduce process costs at the same time.

However, there is a great deal of leverage in the product itself. In the last decade, Oemeta has developed biocide-free machining media that offer the same performance and, in some cases, a longer service life than the biocide-containing predecessor products. This change in the machining process alone:

  • reduces the risk to employees,
  • poses less of a threat to the environment, and
  • Reduces consumption

This has a direct impact on SDGs 3, 6 and 12, without having to fundamentally change the process chain design.

The manufacturer has achieved the greatest sustainability effects by dispensing with mineral oil. However, the development of a mineral oil-free, ester-based cooling lubricant into a 2-component multifunctional oil (MFO) is not only convincing because it dispenses with fossil substances. It also combines cleaning and machining processes. MFOs are optimised for a wide range of applications in the machine tool and the process chain. Thus, it functions equally as well as a hydraulic oil, coolant, cutting oil or even as a cleaner. If various MFOs of the same system are used in the same process chain at the same time, but used for different functions, the unintentional mixing of different media is completely unproblematic, because the products are fully compatible.

If the design of a process chain can be adapted to the properties of the MFO, users can quickly achieve very convincing sustainability effects, namely:

  • the consumption of cooling lubricant is significantly reduced,
  • Cleaning processes are eliminated,
  • Hydraulic and slideway oils can be recycled,
  • Energy consumption is reduced,
  • Renewable raw materials replace fossil, petrochemical raw materials

The changed process design and switch to ester base oils with their very low environmental impact have a direct impact on SDGs 12 and 13.

Refined and multifunctional oils bring huge effects

Two examples are intended to demonstrate that the topic of sustainability can also accelerate the achievement of the UN goals for machining media such as cooling lubricants:

Since the current oil treatment processes produce secondary raffinates, whose quality is in no way inferior to that of the primary raffinates, and with which low viscosities can also be realised, a gear manufacturer switched a large part of the entire gear production to a raffinate-based high-performance treatment oil.

The oil has a viscosity of 15 mm2/s and was designed for all common gear machining processes. Extensive testing was conducted for about a year. After that, a complete changeover was made. Since then, the oil has been used without any discernible disadvantages compared to the previous first-generation oil. The emission per tonne of oil is one tonne less CO2, where the annual demand for processing medium is several hundred tonnes. This example shows how CO2 emissions can be reduced through close cooperation between the oil manufacturer and user. And this is cost and performance-neutral.

At the beginning of the 2000s, a premium car manufacturer converted its crankshaft production to the ester-based mineral oil-free MFO product system "HYCUT" from Oemeta. Because the layout of the crankshaft production line had frequent changes between machining oil and emulsion, the production chain was designed to match the properties of the compatible lubricants. Since the water-mixed fluids are one hundred percent compatible with the non-water-mixed ones, there are no incompatibilities at the water/oil interfaces in the crankshaft line.

This eliminated the need for three intermediate scrubbers that would have been installed with conventional media, and reduced the investment costs considerably. Recycling measures bring further advantages: for example, the cleaning fluid from the remaining intermediate scrubber is processed for further use. An oil-free MFO product is used for parts cleaning upstream of the induction hardening system. MFO deep drilling oil introduced via the parts is emulsified in the washing medium. This creates a valuable high-performance emulsion that can be recycled.

In summary, the advantages are as follows:

  • Lower investment costs
  • Better process reliability
  • Less liquid consumption compared to conventional products

After several years of use, the Institute for Machine Tools and Production Technology at the Technical University of Braunschweig confirmed in a study, according to the standardised LCA method, that the mineral oil-free MFO, HYCUT, has up to 60 % better environmental values and saves 470 CO2 equivalent within one year. The use of the mineral-oil-free MFO, HYCUT, leads to significantly lower environmental impacts in metalworking than a conventional, mineral-oil-based coolant system of the same use.

Focus on the environment, the economy and social acceptance

Perhaps a few more people responsible for machining processes are now thinking about sustainability when it comes to cooling lubricants. The possibilities, facts and examples described make it worthwhile. And it also pays off economically - not to mention the increasingly important social acceptance of companies in light of important UN goals.

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