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Siemens SINUMERIK Controller
Tool Changer · Intermediate · 30-120 minutes
Siemens 6404 - Tool change not possible. Tool not available or not usable
Alarm 6404 occurs when the NCK attempts a tool change via M06 or T-command but the specified tool number is not found in the tool management database or the tool pocket is physically unavailable. This is a servo-related alarm because tool change failures can interrupt motion synchronization and program execution flow.
6404
Siemens 6404 - Tool change not possible. Tool not available or not usable
Tool change not possible. Tool not available or not usable
The desired tool change is not possible. The specified tool does not exist or cannot be loaded. The tool cannot be loaded either if it is part of a multitool which is already active with another tool, or is part of a multitool whose state is 'Change active' in relation to another toolholder Control reaction: NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm.
Root Cause Summary
Alarm 6404 occurs when the NCK attempts a tool change via M06 or T-command but the specified tool number is not found in the tool management database or the tool pocket is physically unavailable. This is a servo-related alarm because tool change failures can interrupt motion synchronization and program execution flow.
Safety
- Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.
Causes and Fixes
- 1
Access Siemens HMI menu: Diagnostics > Parameters > Machine Data > MD 31100 (Tool magazine type). Verify the tool magazine structure matches your hardware configuration and tool pocket count.
- 2
Navigate to Program > Manage Tools or use ShopMill/ShopTurn interface to verify the requested tool number is defined in the active tool table. Check Tool.T parameter entries in NCK via Service > Diagnostics > Tool Management.
Ensure tool table is not in read-only mode (check SD 54100 - Tool table protection).
- 3
Confirm tool pocket assignment via MD 31110 series parameters. Verify tool number maps to a valid pocket number within the magazine capacity defined in MD 31100.
- 4
Reset tool management database if corrupted: Access Service > Database > Tool Management > Reset and reload tool table from backup or manual entry.
This operation clears all tool offset data; restore from backup if available.
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Always verify with your machine manual or a certified technician before performing service procedures.