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18/07/2021 News

Increasing the sustainability of metalworking fluids

How to preserve and store metalworking fluids

Songul Facey from Technical Sales Manager at Total UK Lubricants Division, part of TotalEnergies

 

As awareness of global warming continues to grow sustainability is an increasingly important objective for the manufacturing industry.

As awareness of global warming continues to grow, sustainability is an increasingly important objective for the manufacturing industry. In order to reach carbon neutrality and a cleaner future, metalworking fluid manufacturers are investing in research and development to produce eco-friendly solutions to meet environmental requirements while maintaining productivity.  

Learn how sustainability can be achieved to keep people safe and protect the environment in this blog, or contact our metalworking team for more information

  • Choosing metalworking fluids 

  • Managing fluid quality 

  • System design  

  • TotalEnergies and its metalworking experts 

Choosing metalworking fluids
 

Hazardous components

To achieve greater sustainability, choosing a product that has fewer hazardous components and less toxicity is the primary consideration. 

During metalworking fluid product selection, the base oils and additives should be examined in order to understand any potential harmful effects from a health and safety and environmental perspective. 

It is recommended that oils containing PAHs, PTBBA and chlorinated paraffin, nitrites, sodium nitrate, phenols, alkanol amines, boron and formaldehyde-releasing biocides should be avoided. 

The biocide used should comply with current regulations, and not exceed the required amount to meet fluid specifications. Excessive amounts of biocide may cause skin irritation and dermatitis.  

The product’s SDS will show you which components have negative impacts for health, safety and the environment. Products that have no pictograms or precautionary statements should be the primary choice.  

 

Flammability and resistance to evaporation

Flammability and resistance to evaporation of the metalworking fluid should be examined. 

Flammability increases the risk of fire, particularly in pure cutting and solvent-containing products, and the risk is not eliminated by using soluble lubricant. Metalworking fluids that have a high oil content may also present a flammable risk due to the evaporation of water content.  

The best way to eliminate the risk of evaporation and fire is to choose a product with a high flash point. Products which evaporate easily can also cause severe damage in terms of health and safety, create dirty workshops and be uneconomical due to increased consumption. Products with the highest resistance to evaporation should always be selected.  

As well as hazardous components and flammability, due to petroleum-derived products having low resistance to microbiological formations, oil-free and emulgator-free products are the better choice for sustainable metalworking fluids. They are environmentally friendly and deliver superior lubrication performance. FOLIA is an example of such a product. This revolutionary development in the field of metalworking offers outstanding lubricity and cooling properties, and unparallelled health, safety, and environmental benefits. 

Managing fluid quality 

Once the metalworking fluid is selected, there are specific steps that should be taken in terms of handling and storage.  

Storage

Fluids should be transported and stored between 5°C and 40°C, kept indoors with the original packaging with the lid closed, and protected from sunlight and humidity. They must be used before expiration date.  

If they are stored outside, they should be horizontal so moisture cannot infiltrate the bung, or kept under a protective cover.  

If they have been stored for a long time, the products should be analysed to ensure there is no nitrosamine formation as this is classed as carcinogenic.  

Water quality

Water quality is just as important as the choice of oil. Approximately 90-95% of the water-based liquid sump consists of water, and its quality can vary depending on its source. It may contain dissolved minerals, organic matter, or microorganisms that can affect health and safety as well as performance. 

Having a precise water quality not only ensures emulsion stability but also reduces fluid consumption and disposal. The water used for the preparation of the cutting fluid should be clean and neutral (pH approx. 7) and should be tested regularly to evaluate if it is following the reference values given below. 
 

Sump cleanliness and stability

Before using soluble cutting fluids, the system must be cleared of any dirt, soap, and microbiological residues by adding 1-3% system cleaner to the sump that is going to be changed. The cleaner must run in the system for at least 24 hours before the old sump is emptied. This is to ensure the system has been chemically purged. The system should then be rinsed with water several times, preferably with 1% of the new oil added.  

Sump stability is critical and therefore there is a specific mixing procedure to follow during sump preparation. The use of an automatic mixer is recommended, while at a minimum of 10°C ambient temperature. This will produce a mixture that is balanced in terms of its alkalinity, acidity, and hydrophilic-lipophylic (HLB). 

Monitoring

A sample from the newly prepared sump should be taken as this will help with monitoring the bath and detecting any abnormalities that could cause problems in future. For instance, soluble oils are vulnerable to microbiological attacks and these can deteriorate the quality of the emulsion as well as being bad for workers’ health.  

Regular monitoring and control of the sump parameters can deliver a reduction in the metalworking fluid’s hazardous exposure, extend the lifespan of tools and the sump, and reduce disposal volume. 

The key measurements are given below but vary depending on the product. The Health and Safety Executive requires these to be monitored at the frequency below, with any corrective action taken recorded.   

 

Other parameters to be monitored include appearance, odour, tramp oil content, pressure, flow rate, tank fluid level, temperature, and conductivity. 

System design

Tank size

The size of the tank plays an important role in efficiency and sustainability. If the tank is small, the metalworking fluid can become overheated which can increase the bath concentration rate due to evaporation.  

Topping up the bath with water to adjust the concentration level may increase the hardness and chlorine content, leading to the development of calcium soaps and corrosion problems if the water is not demineralised.  

Other issues that might be encountered are excessive fluid consumption caused by the fluid overflowing due to filter blockage, and accelerated bacterial and fungal formation due to the increase of tramp oil rate. 

If the tank is too large there may be an increase in the development of anaerobic microorganisms caused by poor aeration, as well as ineffective filtration performance and accumulation of deposits. 

Most commonly, the volume of the tank is recommended to be eight times bigger than the volume of the pump flow rate (l/min) for general machining and 16 times more for grinding operations. 

Filtration

By complementing the system with separation equipment like filtration, skimmer, and local exhaust ventilation (LEV), the sustainability of the metalworking fluid’s operation is improved. Before choosing such equipment, certain parameters should be considered, including the properties of both the material and the fluid, the flow rate, and the volume flow. In general, magnetic and sedimentation systems are used for separating solid particles. 

However, filter papers would be more effective to separate the swarf and fine metallic particles as some, such as aluminium and magnesium, can be very reactive and explosive. Also, metals such as nickel, chromium and lead can cause allergic problems. Since cleaning the tramp oil allows fluid to be aired, skimmers and coalescence should be indispensable parts of the separation system. 

In order to minimise the health risks of metalworking fluids’ mist exposure, having adequate control measures as well as installing a LEV system will improve the air quality in the workshop. 

Sustainability and productivity

Achieving a more sustainable and less toxic hazardous production system without sacrificing productivity is certainly possible. Following all the measurements, beginning with product selection and a commitment to continuous maintenance, and proper system design are what is required to achieve this. By doing so, we can get one step closer to reducing hazard and toxicity, increase process efficiency, and reduce the consumption of chemicals and the subsequent creation of hazardous waste.  

TotalEnergies and its metalworking experts

TotalEnergies has decades of experience delivering and developing metalworking fluids for customers across the globe. 

Find out why TotalEnergies is the metalworking partner of choice.