M07 CNC Code Explained: An Easy Intro for Beginners [Mist Coolant]

What does the M07 CNC code do?

M07 is a modal command which turns on mist coolant.

Mist coolant is compressed air and coolant (usually oil). 

It can be more efficient than flood coolant and in some situations be better at clearing chips than flood coolant, but it is used far less often than flood coolant with the M08 command.

M07 [mist coolant] vs M08 [flood coolant]

The most common type of coolant used in CNC machining is flood coolant using the M08 code.

Flood coolant is where the cutter and workpiece are literally flooded with the coolant fluid. This works to lubricate the part, remove chips, and reduce heat buildup.

Mist coolant with the M07 code combines the coolant fluid with compressed air and sprays it on the cutting area.

Mist coolant uses less coolant fluid and can be less messy depending on your CNC setup, but it isn’t as good at reducing heat buildup as flood coolant is.

cnc machine table with coolant lines and spindle shown
Flood coolant in action

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Advantages of using coolant

The three main advantages of using coolant with your CNC machine are:

  • Lubricate the cutter
  • Clear chips
  • Reduce heat buildup

What are the other options for using coolant?

We discussed mist and flood coolant above but there are other options available as well including:

  • Air: This type of coolant reduces heat and clears the chips, but it does not lubricate the workpiece. This type of coolant is used more often with sensitive materials.
  • High pressure: High pressure coolant is similar to flood coolant. The only difference is that it hits the workpiece at greater than 1000psi. The higher pressure and higher quantity of coolant helps cool the cutter better and remove more chips.
  • Through spindle: Through spindle coolant delivers the coolant directly where it is needed. It is better at clearing chips in many cases because the coolant from the spindle pushes the chips out of a hole or pocket.

How to turn off coolant

The M-code to turn coolant off is M09.

However, there are other stopping commands that also turn off coolant as part of their function including:

Frequently asked questions about the M07 code

Does every CNC machine have coolant capabilities?

Yes and no.

You can expect that all industrial level CNC machines will have coolant capabilities.

Home or hobbyist level machines such as CNC routers often do not have coolant capabilities, but they can usually be added on if needed.

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CNC routers do not usually come with coolant functions

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