Choosing the right metalworking lubricants and maintaining them appropriately can make a significant difference to the efficiency and productivity of your operations. Finding the right fluid can protect your products from corrosion, ensure a clean finish and make manufacturing smoother.

At the same time, using best practices when applying, cleaning and maintaining each metalworking fluid can extend the lifespan of your machinery, reduce wear and cut down on maintenance requirements. On the other hand, failure to do so can lead to poor cutting efficiency and damage to your equipment, resulting in unscheduled downtime and cost.

There are many different metalworking fluids used at different stages of the manufacturing process, and each one needs to be maintained separately. This is because each product has a different function, is used in a different way, and comes with its own unique risks of contamination.

Here, the technical experts at Broughton Lubricants break down the different types of metalworking fluid, explain how you can identify that you need to clean them, and discuss the best practices that can enable you to make the most of your equipment.

Which types of metalworking fluid need to be kept clean?

There are a variety of metalworking fluids used at various stages of the manufacturing process in the production of steel and other metal products. These include:

• cutting fluids, which lubricate tools to maximise their lifespan and help to maintain a consistent temperature;
• quenching fluids, which are used for cooling and hardening metals, and which can confer various properties depending on the additives they contain; and
• cleaning fluids, which remove swarf and other residues, and often leave behind a protective coating on the finished product's surface.

Where these metalworking fluids are stored in sumps, it is vital to maintain them carefully and keep them clean. Otherwise, there can be problems not only for your metal products, but for employees. Sumps are at risk of microbial growth and contamination, which can result in impaired lung function if workers breathe in mist generated by these fluids, or irritation or dermatitis in cases of direct skin contact.

In all cases, proper maintenance is vital to ensure that you get the most from your fluids, but it is especially important to keep sumps clean and avoid health risks, in order to meet the necessary occupational safety standards.

How do you know if metalworking fluids need to be cleaned?

Fluids used in metal production processes can regularly accumulate metal particles and other contaminants, which reduce their effectiveness and, in the most serious cases, can present a health and safety risk.

In particular, water-soluble oils are vulnerable to bacterial contamination, which often requires you to carefully clean the oil, the sump and any products or tools that have been in contact with the oil.

One of the first steps you can take to check if a metalworking fluid sump needs to be cleaned is by visual inspection. There are several key visual symptoms that may indicate that it is time to clean your metalworking fluid - investigate further if you notice any of the following:

• Cloudiness
• Changes in colour
• A separated (split) emulsion or foaming
• Strange odours
• Visible debris, particulate matter or swarf
• A layer of biofilm
• A low sump level (indicating high water volume that is causing fluid to evaporate)

Other tests you need to take on a routine basis include:

• Concentration (usually by using a handheld refractometer)
• pH (by using disposable strips of a meter)
• Tramp oil contamination (visual inspection, or by measuring the percentage in a measuring cylinder)
• Bacterial growth (usually using dipslides

If any of these tests are consistently out of specifications then it could indicate that it is time to conduct a cleanout of the sump and dispose of the mixed fluid.

For lubricants that are not designed to be mixed with water (neat lubricants), the best indication that they need to be replaced may be following results of analytical analysis or the performance of the equipment. If you experience increased wear or need to increase your maintenance efforts, this may be a sign that the metalworking fluid you have applied needs to be cleaned off and reapplied. Better still, routine analytical analysis can be critical in assessing the condition of the lubricant with pass / fail parameters or trend analysis used as an indicator that it is time to change the fluid. Routine analysis may include measurement of elements indicating contamination or consumption of additives and the presence of metallic and non-metallic debris.

It is vital to successfully maintain metalworking fluids and keep them clean, as contamination has risks not only for your products. Workers may experience health issues such as a skin rash, respiratory conditions, breathing difficulties or eye irritation if the metalworking fluid they work with is contaminated - while this can be a sign that the fluid needs to be cleaned, it is important that you do so before the risk of health problems arises. You have a legal responsibility to ensure that you meet the minimum standards of health and safety, which includes preventing health problems that may result from handling contaminated lubricants.

How can I effectively maintain metalworking fluids?

Regular maintenance of metalworking fluids can help to ensure that they continue to function efficiently and safely. This includes regularly checking and adjusting the concentration of the fluid according to the manufacturer's recommendations and the requirements of your application. You should ideally check the concentration of a water-soluble metalworking fluid once per day and make adjustments, in order to achieve the best possible results.

As well as adjusting the concentration, you should skim (or pump) away any tramp oils that have risen to the surface. Tramp oil adversely affects the metalworking fluid as it cuts off the air supply to water-based fluids and provides nutrients to bacteria that live inside. This allows bacteria to thrive and increases the risk of significant contamination, as well as the risk of workers developing conditions like work-related asthma and even chronic bronchitis.

You will achieve the best possible results by skimming daily, but as long as you maintain a consistent and regular schedule, you will achieve the best possible lubrication throughout your operations.

You can purchase a skimmer that performs this function - whether a simple manually operated device or an automated system - but you must ensure that you carry out this maintenance regularly.

Another way to keep metalworking fluids clean is by using microfiltration. This involves passing the fluid through a series of filters to remove metal particles, bacteria and any other remaining contaminants. Alternatively, the use of centrifuges to spin oil at high speed and separate contaminants from fluid is a highly effective option and more effective than filters in some cases.

So there are various ways to maintain a clean healthy metalworking fluid and our technical experts at Broughton lubricants can help you choose the most appropriate methods depending on the specific needs of your application.

How should I clean a metalworking fluid

In addition to these maintenance tasks, it is important to properly dispose of metalworking fluids once they have reached the end of their useful life. Metalworking fluids can be hazardous to the environment and should be disposed of in accordance with local regulations.

Your manufacturing processes will determine when you need to change your oils, but this is not always clear. If you need advice, the expert industrial lubricants team at Broughton Lubricants can help. With many years of technical experience, our advisors can offer vital advice and guide you towards the best possible product for your application.

You should use an industrial cleaning fluid to clean the sump (often referred to as a system cleaner) - do not use water alone, as this does not have the necessary antibacterial properties and surfactants to remove high-risk contaminants.

Once the oil has been removed from the sump for cleaning, you should fully clean out the sump before replacing the oil. Do not put clean fluid into a dirty sump, as this will render the cleaning process ineffective. Safe handling procedures should also be followed, to avoid the risk of skin exposure to metalworking fluids.

If you want to upgrade your metalworking fluids to enjoy better performance, shop our range of Castrol metalworking fluids, including the XBB range for improved machining performance and surface finish, and the Techniclean 90 XBC industrial process cleaner.

For advice on a particular application, call our expert team today on 03300 555 655, or use the enquiry form on this page to request a call back.