How to Fix the “Fanuc Not Ready” CNC Control Issue

It’s a Monday morning on the factory floor, and your CNC machine operators are ready to start a new week of operations. And just when you think all equipment is ready for production, an error code of “not ready” deflates your day before it even begins.

Dealing with a Fanuc CNC control stuck in a “not ready” state can be incredibly frustrating. However, it can also be a significant concern if production schedules are delayed, which can mean dissatisfied clients and customers. This guide provides a step-by-step approach to resolving this common issue, ensuring your CNC machine is back up and running in no time. These tips offer practical solutions whether you’re facing a hard limit on one of your table axes or an issue with your Z-axis. Our answers are based on extensive experience and tailored for easy understanding and implementation.

Common Causes of the “Not Ready” State

CNC machine operators must always remember to put safety first. Ensure safety measures are in place before troubleshooting any issue with a CNC machine system.

Hard Limit on Axes

A frequent reason for a Fanuc CNC control being in a “not ready” state is hitting a hard limit on one of the table axes or the Z-axis. This happens when the axis has moved so far that it hits a hard safety stop, preventing further movement. Unlike soft limits, which can sometimes be bypassed, hard limits require physical intervention to resolve.(Bypass switches would be for hard limits) For soft limits, once you clear them, you would reset them using parameters 1320/1321.

Insufficient Air Pressure

Ensure that your machine has adequate air pressure. Many Fanuc CNC machines require a constant supply of compressed air to operate correctly. If the air pressure is too low, the machine may not transition out of the “not ready” state.

Power Supply Issues

Check that all power rails are functioning correctly. This includes verifying that your rotary phase converter or other power converters provide consistent and correct three-phase power. Any interruption in the power supply can prevent the machine from being ready.

Step-by-Step Solution to Fix the “Not Ready” State

1. Initial Checks

1. Check Air Pressure: Ensure your machine has sufficient air pressure.
2. Verify Power Supply: Make sure your three-phase power supply is stable and all legs are active.

2. Power Down and Manual Adjustment

1. Turn Off the Machine: Completely power down your CNC machine.
2. Manual Ball Screw Adjustment:
   • If the issue is with the Z-axis, manually adjust the ball screw. With the power off, you can turn the ball screw by hand to move the servo and spindle assembly. This helps in releasing the hard limit switch.
   • For the X and Y axes, you may need to remove a small cover to access the ball screw. Turn the ball screw to move the axis away from the hard limit.

3. Emergency Bypass

• Emergency Bypass (if available): Some CNC machines have an emergency bypass function for soft limits. Hold the emergency bypass button while moving the handle to release the soft limit. However, this will not work for hard limits.(This is the only way to remove a hard limit unless you rotate the ball screw by hand) Bypass switches will be implemented by the machine tool builder to overcome and reset hard limit conditions.

4. Soft Limit Override

• Soft Limit Override Using Pecan Method:
  • Turn Off the Machine: Ensure the machine is completely off.
  • Hold P and Cancel: While turning the machine back on, hold the “P” and “Cancel” buttons. This disables the soft limits during boot-up, allowing you to move the machine without triggering the soft limit alarms.

5. Final Check and Restart

1. Reposition the Axes: After adjusting the ball screws, make sure all axes are in positions where they won’t hit the hard or soft limits.
2. Restart the Machine: Power up the machine and check if the “not ready” state has cleared.

Preventative Measures

Regular Maintenance

• Check Hard Limit Switches: Regularly inspect hard limit switches and ensure they are not overly sensitive.
• Maintain Air Pressure: Ensure air pressure levels are consistently within the required range.
• Power Supply Stability: Regularly check and maintain your power supply system to avoid fluctuations.

Documentation and Labeling

• Label Relays and Components: Clearly label all relays and components in your electrical cabinet. This makes troubleshooting easier when issues arise.
• Create a Baseline Documentation: Document your machine’s normal operational states. Note which relays are active and what normal looks like when the machine is running correctly.

Training and Practice

• Familiarize yourself with the machine manual: Keep a copy of your machine manual handy and refer to it for specific troubleshooting steps.
• Practice Emergency Procedures: Regularly practice the steps for releasing hard and soft limits to prepare you for issues.

Turn Not Ready into Always Ready

Resolving the “Fanuc not ready” issue involves a combination of understanding your machine’s systems, performing manual adjustments, and utilizing emergency bypass methods. Following the steps outlined above, you can effectively troubleshoot and resolve this common issue, ensuring minimal downtime for your CNC operations. Remember to perform regular maintenance and document your machine’s normal operations to make future troubleshooting easier.

Contact T.I.E. Industrial today for more detailed troubleshooting and access to a wide range of refurbished Fanuc CNC machine parts. As a leading supplier of refurbished Fanuc replacement parts, we offer comprehensive support and an extensive inventory of high-quality parts to keep your CNC machines running smoothly so your company meets all production objectives that drive your success.