What causes FANUC alarm 315?

Machine system or function indicated by the alarm name has detected a fault. Control parameter or configuration error related to the alarm condition. Hardware component fault on the CNC or machine. Part program error or illegal operation for the indicated function. Machine interlock or safety condition not satisfied.

How do I fix FANUC alarm 315?

1. Note the alarm number and check the Fanuc alarm screen for any sub-code or additional details. 2. Identify the specific machine system or function from the alarm name. 3. Power cycle the machine to clear transient faults. 4. Consult the Fanuc parameter or operator manual for alarm 315 specific remedy. 5. Contact Fanuc service if the alarm persists after basic troubleshooting.

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FANUC Controller

Program/G-code · Basic · 10-20 minutes

Alarm 315

Fanuc Alarm 315 - ILLEGAL NOSE ANGLE COMMAND IN THREAD CUTTING CYCLE

Alarm 315 occurs when the Q address (tool nose angle) in a G76 threading cycle contains an invalid value. The Q parameter must be one of the eight valid tool tip angle codes (0-8) corresponding to standard insert geometries. Any value outside this range or decimal values will trigger this alarm immediately during program execution.

FANUCProgram/G-codeBasic10-20 minutes

315

Fanuc Alarm 315 - ILLEGAL NOSE ANGLE COMMAND IN THREAD CUTTING CYCLE

SYSTEM ALARM 315

Root Cause Summary

Alarm 315 occurs when the Q address (tool nose angle) in a G76 threading cycle contains an invalid value. The Q parameter must be one of the eight valid tool tip angle codes (0-8) corresponding to standard insert geometries. Any value outside this range or decimal values will trigger this alarm immediately during program execution.

Causes and Fixes

1
Review the G76 threading block in the active program. Locate the Q address value which specifies the tool nose angle (imaginary tool tip direction).
2
Verify Q value is within valid range: Q0 (0°), Q1 (90°), Q2 (180°), Q3 (270°), Q4 (45°), Q5 (135°), Q6 (225°), Q7 (315°), or Q8 (no offset). Refer to Fanuc lathe programming manual section on G76 parameters.
3
Correct the Q address to match actual tool insert geometry. For standard external threading tools with top approach, typically use Q0 or Q8 depending on tool orientation.
4
Reset alarm using RESET key, return to program start, and re-execute the threading cycle to verify correction.

DIY Feasiblehigh confidence

Call a technician if:

·Parameter 5143 needs modification but is password protected
·Alarm persists with known good P parameter values

Prevention

Create standardized G76 templates with validated P parameters
Document approved nose angles for your tooling
Use parameter 5142-5143 to understand machine-specific threading limitations

Common Mistakes

Using nose angle values above 80 degrees
Omitting leading zeros in P parameter
Copying G76 blocks between different machine types without validation

Related Alarms

314 316 317

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