M08 G-Code Command

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M08 G-Code Command

M08 is a CNC coolant code used in CNC machining that turns on flood coolant for the main spindle. Flood coolant is the most common type of coolant used in CNC machining and is aimed directly at the cutting edge of the tool. Flooding the area with coolant has multiple benefits.

What are the benefits of using flood coolant?

There are several benefits of using flood coolant in CNC machining:

  1. Cooling: The primary benefit of flood coolant is that it cools the cutting tool and the workpiece. The coolant helps to dissipate the heat generated during the cutting process, which increases tool life and prevents workpiece deformation due to thermal expansion.
  2. Lubrication: The coolant also acts as a lubricant, reducing friction between the tool and the workpiece. This reduces tool wear and improves surface finish.
  3. Chip evacuation: The coolant helps to flush chips away from the cutting area, preventing chip buildup and reducing the risk of chip recutting.
  4. Corrosion prevention: Certain coolants contain rust inhibitors that help to prevent corrosion of the machine and workpiece.
  5. Improved tool life: By reducing heat and friction, flood coolant can significantly extend the life of cutting tools.

Overall, the use of flood coolant can improve machining accuracy, increase tool life, and reduce the risk of tool failure and workpiece damage.

How M08 G-Code Command Is Used

Here’s an example of M08 being used in a G-code program with comments in brackets:

T1 M06                 (Tool call and tool change)
G00 G90 G54 X0 Y0      (rapid move to starting position)
G43 H1 Z50             (set tool length offset and move to safe Z height)
M08   (turn on flood coolant)
G01 Z-5 F5      (feed to cutting depth)
G01 X10 Y10 F100   (linear move to cutting position)
G01 X20 Y20   (continue cutting)
G01 X30 Y30   (continue cutting)
G00 Z50       (retract tool to safe height)
M09   (turn off coolant)
G91 G28 X0 Y0 Z0   (rapid move to home position)
M30    (end program)

In this example, the program starts by calling up Tool #1. Then it sets G54 as its offset and commands a rapid move to the starting position at X0, Y0. Then it sets the tool length offset for tool 1 and moves to the safe height position.

The program then turns on the flood coolant using the M08 code.

The following line plunges the cutter to a depth of -5 into the workpiece. Then it makes a linear move to the cutting position at X10, Y10, with a feed rate of 100 units per minute. Once the cutting position is reached, The program then continues cutting at X20, Y20, Z-5 and X30, Y30, Z-5. After the cutting is complete, the program turns off the coolant using the M09 code and makes a rapid move back to the home position at X0, Y0, Z0.