What causes FANUC alarm 050?

CHF or CNR chamfering command used in the same block or cycle as G32/G92/G76 threading. Post-processor generated chamfer code that conflicts with active threading cycle. Program copied from a turning center with different threading syntax. Corner rounding R value programmed in a threading block.

How do I fix FANUC alarm 050?

1. Locate the threading block where the alarm triggered. 2. Remove any CHF, CNR, or corner rounding R commands from within the threading cycle. 3. Perform chamfering in a separate finishing pass after thread cutting is complete. 4. Verify the program against the Fanuc programming manual threading section.

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FANUC Controller

Program/G-code · Intermediate · 30-60 minutes

Alarm 050

Fanuc Alarm 050 - CHF/CNR NOT ALLOWED IN THRD BLK

Fanuc Alarm 050 occurs when the spindle fails to reach the commanded orientation position within the time limit specified in parameter 4077 (orientation completion time). This is typically caused by mechanical issues with the orientation mechanism, incorrect parameter settings for orientation speed/positioning, or sensor feedback problems preventing the CNC from detecting successful orientation.

FANUCProgram/G-codeIntermediate30-60 minutes

050

Fanuc Alarm 050 - CHF/CNR NOT ALLOWED IN THRD BLK

CHF/CNR NOT ALLOWED IN THRD BLK

Root Cause Summary

Fanuc Alarm 050 occurs when the spindle fails to reach the commanded orientation position within the time limit specified in parameter 4077 (orientation completion time). This is typically caused by mechanical issues with the orientation mechanism, incorrect parameter settings for orientation speed/positioning, or sensor feedback problems preventing the CNC from detecting successful orientation.

Safety

Tool change may fail

Causes and Fixes

1
Navigate to SYSTEM > PARAM and check parameter 4077 (orientation completion time limit in seconds). Typical values are 5-15 seconds. If below 5 seconds, increase incrementally to 10 seconds.
2
Check parameter 4073 (orientation speed in rpm). Verify it matches spindle capability, typically 20-100 rpm. If too low, increase to reduce orientation time.
3
Verify parameter 4075 (in-position width in degrees). Standard setting is 1-5 degrees. Too narrow a window may prevent orientation completion detection.
4
Check parameter 4074 bit settings for orientation mode (bit 0: direction selection, bit 1: one-directional). Ensure mode matches mechanical orientation capability.
Changing orientation direction parameters may affect tool change reliability. Document original settings before modification.

DIY Feasiblehigh confidence

Call a technician if:

·Spindle encoder feedback errors persist
·Parameter access restricted
·Threading cycles fail after program correction

Prevention

Always cancel C and R commands with C0/R0 before threading
Use separate blocks for geometric operations and threading
Establish programming standards for modal command management

Common Mistakes

Leaving modal chamfer/radius active
Confusing G76 R parameter (relief) with corner radius
Mixing geometric and threading operations in same block

Related Alarms

049 051 200 201

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