Types of Coolant for CNC machining

The importance of using coolant for CNC machining

Machining using CNC (Computer Numerical Control) technology has a wide range of applications in fabrication and manufacturing. CNC machining is especially convenient in settings that demand large quantities of items produced in a tight time.

They are definitely one of the most crucial parts of the machining process and are in charge of prolonging the tool’s life. Breakdown of the coolant system can result in poor product quality, machining bottlenecks, and costly downtimes.

Keep reading to learn more about different types of coolants for CNC machining.

Why do we use coolants in CNC machining?

Before moving to the types of coolants, we have to say some basics of machining coolant. It is also known as a cutting fluid. It is a specific lubricant type that helps CNC machines to easily cut different materials, including fiberglass, metals, high density plastic, and so on.

When technicians operate at low cutting speeds, the coolants are in charge of lubricating the process of cutting. On the other side, at high speeds of cutting, the coolant cools the workpiece. Operators can also use coolant to keep the entire workpiece free of debris and other particles coming from the cutting process.

Benefits of coolant in CNC machining:

  • Protecting the workpiece against deforming due to intense heat
  • Cooling hot surface to provide safe handling of the workpiece and the machine
  • Protecting the machine from corrosion
  • Improving machine lifespan

Types of coolant used in CNC machining

Machining coolants are categorized into the four following categories: synthetic fluids, semi synthetic fluids, soluble oils, and straight oils.

Synthetic fluids

Synthetic fluids usually contain 17 ingredients, including polymers in charge of replacing the oil and cutting additives that can be found in semi synthetics and soluble oils. Instead of mineral oils and petroleum, synthetic fluids contain organic and inorganic alkaline ingredients. These cutting fluid types protect the machined workpiece from corrosion. However, their lubrication is the least. 

Semi synthetic fluids

These types contain both synthetic (polymer) and oil. These types of fluids can contain from 5% oil to 35% oil. To put it simply, they contain the best of both worlds. The smaller percentage of oil allows for heat to be way faster dissipated than with soluble oils, improving finish and tool longevity.

Soluble oils

These types are most common and, and in most cases, form an opaque, milky fluid. In general, soluble oils are those with 50% oil or even more. They are balanced by additives and emulsifiers. Heavy duty soluble oils contain chlorine in charge of enhancing extreme pressure machining. These oils provide high lubricity and outstanding corrosion control for the machine and its parts. However, emulsifiers are well known as a good source for bacteria.

Straight oils

They are not diluted in the water, at least most of them, and primarily consist of petroleum or mineral oil base. Straight oils contain other elements of lubricating like vegetable oils and fats. They are great lubricants but are not performing well when it comes to cooling of machines or workpieces.

So what type of coolant does your CNC machine need?

Like any type of maintenance fluid, the type of cutting liquid you need will depend on your CNC machine make and model, as well as the type of material you’re working. Often you can refer to your owners manual or contact the CNC manufacturer if you’re unsure which coolant to use.

But if your machine or CNC project requires speciality knowledge or adaptation, consider calling a CNC routine maintenance service. The right company can keep your machines running smoothly and supplied with proper fluids so your time can be devoted to production. 

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