Question

With reference to the part program on CNC Lathe; code M05 refers to:

• A. Spindle start clockwise
• B. Spindle start counter clockwise
• C. Spindle orientation
• D. Spindle stop

Hint:

Think of the sequence: 3 starts it, 5 stops it. In your head, link M03 $\to$ M04 $\to$ M05 as Clockwise $\to$ Counter $\to$ CUT!

Answer 1

The Correct Option is D

CNC (Computer Numerical Control) machines use a standardized set of commands known as G-codes (preparatory functions) and M-codes (miscellaneous functions) to control the machine's hardware. 1. Understanding M-Codes: Miscellaneous codes (M-codes) control the "on/off" actions of the machine, such as the spindle, coolant, and tool changes.

2. Decoding Spindle-Related M-Codes: To operate a CNC lathe, there is a specific sequence for the spindle:

• M03: Spindle ON (Clockwise rotation).

• M04: Spindle ON (Counter-clockwise rotation).

• M05:

Spindle STOP. This command cuts the power to the spindle motor and typically applies a brake to bring it to a complete halt before a tool change or at the end of a program.

3. Role of M05 in Part Programming: The M05 command is critical for safety and process control. It is always used:

• Before the machine performs an automatic tool change (M06).

• When the operator needs to inspect the part or clear chips manually.

• At the very end of the part program (often just before M30).

4. Conclusion: According to the Fanuc and ISO standards for CNC programming, M05 is the universal miscellaneous function for stopping the spindle.