Oest - Metal Cutting Fluids

When oil companies roll out the same narrative it’s hard to choose the best metal cutting fluid in a saturated market.  Look around the internet at the different companies and you find the usual and common selling proportions: –

  • The oil quality,
  • long tool life,
  • clean machines,
  • low drag-out,
  • great lubricity
  • and many more selling propositions.

Where does an Engineer start?

Do you go with a name you recognise? “That’s a famous brand I’ll be safe with them”, or “we’ve always used them” or do you select the 100-year-old oil company with a holistic view of manufacturing?

How many oil companies talk about the manufacturing steps that follow machining or forming operations? Until working with the 100-year-old German oil producer, Oest, I had not heard of this much broader industry approach. If fact looking at the big four competitors to Oest, non appear to mention the impact of oil chemistry on cleaning outcomes. What happens to your precious components next, has equal importance to Oest as the metal cutting process itself.

Most metal components require degreasing after a wet manufacturing step. Parts are usually washed in water-based detergents or solvents, ready for inspection, shipping and assembly. Some go onto other manufacturing steps where residues can contaminate the next process, resulting in process downtime, remedial work and substandard parts. In every metal cutting business, your degreasing system requires the same technical level of attention given to your CNC machines.

Oest is a company that has developed a wide range of machining oils and machine lubricants that perform the intended task and have a unique feature of high compatibility with your parts cleaning systems.

Why is this unique Oest compatibility important?

Oest has spent the last two decades working with cleaning media suppliers to ensure Oest products are truly optimised for the task in hand and with degreasing application chemistry. All manufacturing oils and lubricants have additives to help them fulfil their mission effectively. If not carefully chosen by the oil manufacturer, these additives and the base oils can create many cleaning and degreasing system problems. These issues are generally chemical in nature and result in machine operational issues and part cleanliness problems. With many resulting in adverse outcomes such as these examples below: –

A loss of solvent stability

Chlorinated and sulphated oils or oils with poorly selected fractions can result in solvent stabilisers being continuously depleted, requiring more than average stabilisation. An optimised oil and solvent degreasing system will use very little stabiliser during everyday use.  Excessive stabilisation becomes very expensive over time and sometimes a time-consuming task that is avoidable with the correct oil selection.

Your vapour generators foaming.

It’s the oils removed from components that foam, not the solvent. Foaming occurs during the washing cycle when a pressure change happens inside the degreasing machine, such as during the vapour degreasing phase. This foaming contaminant gets carried around the degreaser, contaminating parts you’re attempting to clean and compounds the problem by spoiling the distilled cleaning media. Oest oils chemistry is carefully selected to avoid this preventable outcome.

Example of thermal decomposition in a degreasing system

Thermal decomposition of your manufacturing oils

Cutting oils and its additives can lead to stains appearing on components, undesirable solids forming in the vapour generator and pipework, excessive foaming and alkaline production and acid formation.  This leads to machine instability and cleaning issues with increased maintenance and the real potential for corrosion to the machine’s internals. Oest oils avoid this outcome using selected base oils and additives.

Co-distillation of oil additives

Can have very different boiling points to the base oil material. The result is co-distillation which means the contamination boils at a similar temperature to the solvent, travelling around the machine indefinitely. Over time the co-distilled contamination builds up in the solvent, eventually showing up on parts as wet patches or stains. The only solution is an avoidable expensive bath exchange. Selecting an Oest oil will avoid co-distillation because all the fractions making up the oil boil at higher temperatures

Lubricant boiling point

Neat metal cutting oils typically have boiling points around 280-320C which are well above the solvents’ operating temperatures. Water-based fluids used in transfer presses can have much lower boiling points. This group of cutting fluids is very compatible with water-based detergent cleaning systems. Still, the boiling point of the lubricant is critical to good results when working with solvent degreasers.

Lubricant flashpoint

Metalworking fluids have flashpoints ranging from 50 – 300°C These factors usually are not relevant if you are working with detergent washing systems. However, they are an essential consideration when running solvent-based systems. For lower flashpoint oil products, you must work with solvents and systems design for the purpose such as cold cleaners or degreasing systems design for modified alcohols or hydrocarbons. If this is not an option, then consider changing your oil to one with a higher flashpoint.

Tramp oil building up in CNC machines

Any biologicals are left behind following the clean down, will continue to grow and the problem is re-established, resulting in a shortened coolant life.  Another impact of tramp oils creating a biological botanical garden is the resulting drop in PH.  A low PH fluid entering

Mineral salts from hard waterMixing coolants with hard water

Many coolants operate fine with hard water at the CNC machine but can cause problems later as mineral salts build-up in the sump. Over time the water evaporates or is lost through machining and drag out. It is topped up with fresh coolant to maintain operating levels. The mineral salts get left behind sinking into parts of the sump were agitation is minimal, resulting in a white build-up of sediment. This progressive hardening of the water translates into cleaning and degreasing problems. In particular, chlorinated solvents will tend to leave behind mineral salts on the parts, usually in small radii or the root of threads, see our example. There are several solutions to this dilemma,

• drain and thoroughly clean the CNC machine more often,
• change the cleaning media that one is more compatible with salts
• or condition your water supply and use a coolant suitable for soft water operation.

The later is generally the better long term solution as it removes the root course and the associated maintenance.

Oil Density

More common in polishing or rust protection applications, the oil density can significantly impact cleaning outcomes. Less so with solvent-based cleaning systems, since the solvent and oil effectively become one until distilled. But detergent-based cleaning systems behave differently with oils captured by the detergent either floating or in some cases sinking. To have both types of oil in a single cleaning machine is a recipe for disaster since most cleaning machines are geared up to handle either floating or sinking contaminants not both.

Oil Viscosity

Closely related to the associated density issues, viscosity can lead to cleaning problems. In CNC applications this is more likely to be greases used in bearings. Greases are generally acceptable in a solvent system. Still, they can lead the substantial build-up of fat around the water line or sink to the bottom to in detergent cleaning systems
There are thousands of degreasing systems here in the UK, with most removing some type of lubricant. If your cleaning system is expensive to maintain, problematic or appears on the production meeting agenda too often, perhaps you are experiencing a symptom of oil selection rather than a failing degreaser?

Use our “Contact Us” form for a free no-obligation discussion about your challenges. We can assist you in investigating the root cause and offer solutions, with our state of the art analysis laboratory at Oest Group. Oest, 100 years of experience and a 350 million turnover fluid business taking the broader view of manufacturing, solving your headaches by removing your degreasing process from the production teams meeting agenda whilst delivering industry anticipated high-quality performance.