Coolant control (M08, M09) in CNC Programming - Step-by-Step Execution

Concept Flow - Coolant control (M08, M09)

Start Program

↓

Check for M08

Yes / No↓

Turn ON Coolant

↓

Coolant ON

↓

Turn OFF Coolant

↓

Continue Program

↓

Coolant OFF

↓

Continue Program

↓

End Program

The program checks for M08 to turn coolant ON and M09 to turn coolant OFF, then continues execution.

Execution Sample

CNC Programming

N10 M08 ; Turn coolant ON
N20 G01 X10 Y10 F100
N30 M09 ; Turn coolant OFF
N40 G00 X0 Y0

This CNC code turns coolant ON at line 10, moves the tool, then turns coolant OFF at line 30.

Execution Table

Step	Line	Command	Coolant State	Action Taken
1	N10	M08	OFF -> ON	Coolant turned ON
2	N20	G01 X10 Y10 F100	ON	Tool moves with coolant ON
3	N30	M09	ON -> OFF	Coolant turned OFF
4	N40	G00 X0 Y0	OFF	Tool moves with coolant OFF
5	-	-	-	Program ends

💡 Program ends after last line; coolant state remains OFF.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	After Step 4	Final
Coolant State	OFF	ON	ON	OFF	OFF	OFF

Key Moments - 2 Insights

Why does the coolant state change only at M08 and M09 lines?

Because M08 turns coolant ON and M09 turns it OFF, as shown in execution_table steps 1 and 3. Other commands do not affect coolant.

What happens if M09 is missing after M08?

Coolant stays ON after M08, so it remains ON until turned OFF or program ends, as seen in variable_tracker final state if step 3 was skipped.

Visual Quiz - 3 Questions

Look at the execution table, what is the coolant state after executing line N20?

A ON

B OFF

C Turning ON

D Turning OFF

💡 Hint

Check execution_table row 2 under 'Coolant State' column.

At which step does the coolant turn OFF?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at execution_table row 3 for coolant state change.

If M08 was not used, what would be the coolant state at step 2?

A ON

B OFF

C Turning ON

D Unknown

💡 Hint

Refer to variable_tracker and execution_table to see coolant state changes only happen at M08 and M09.

Concept Snapshot

M08 turns coolant ON.
M09 turns coolant OFF.
Coolant state persists until changed.
Use M08 before cutting moves.
Use M09 to stop coolant after cutting.
Commands between do not affect coolant.

Full Transcript

This CNC program uses M08 to turn coolant ON and M09 to turn it OFF. The flow checks for these commands and changes coolant state accordingly. The execution table shows each line's command and coolant state changes. The variable tracker follows coolant state through the program. Key moments clarify that only M08 and M09 affect coolant. The visual quiz tests understanding of coolant state at different steps. Remember, coolant stays ON after M08 until M09 turns it OFF.