Common troubleshooting methods for CNC machine tools - Solutions - Huaqiang

Single chip microcomputer STM32L151CCU6

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

SMD aluminum electrolytic capacitor

L0504-Murata muRata common mode inductor 90Ω 150mA

When dealing with CNC machine tool faults, the complexity often exceeds the self-diagnosis capabilities of the system itself. This can lead to multiple potential causes being indicated by a single alarm number, making it challenging for technicians to identify the root issue. Below are several practical troubleshooting methods commonly used by maintenance professionals in real-world scenarios:

1. Visual Inspection Method: This involves observing any unusual lights, sounds, or smells during a fault. It helps narrow down the problem to a specific module or circuit board. The process includes: - Asking the operator about the incident and the conditions under which the fault occurred. - Physically inspecting the machine for signs of damage, burnt components, or loose connections. - Touching the boards and connectors while the machine is off to detect loose or faulty parts. - Powering the machine on to check for smoke, strange noises, or overheating. Example: A CNC machining center experienced intermittent CRT display issues. Upon inspection, it was found that two pins on a crystal were poorly soldered. After re-soldering, the issue was resolved.

2. Initial Reset Method: For transient faults, resetting the system or power cycling can clear the issue. If memory corruption occurs due to battery failure or power loss, a system reset may be necessary. Always back up data before performing this step.

3. Self-Diagnosis: Modern CNC systems have built-in diagnostic tools that monitor hardware and software. They can display interface status and fault codes, helping determine if the issue lies in the mechanical or control part of the system.

4. Function Program Test: By running test programs that simulate G, M, S, T, and F commands, technicians can quickly identify whether the problem is in the program or the system. This method is especially useful when random failures occur or after long periods of inactivity.

5. Spare Parts Replacement: Replacing suspected faulty components with known good ones can help isolate the problem. This approach is widely used in modern CNC maintenance to minimize downtime. However, care must be taken not to replace critical components like the CPU or memory unless absolutely necessary.

6. Cross-Transposition Method: When spare parts are unavailable, swapping compatible components between different axes or modules can help identify the faulty part. This requires careful attention to wiring and parameter settings to avoid introducing new problems.

7. Parameter Check: System parameters are crucial for proper operation. Incorrect settings can cause malfunctions. Checking and correcting these parameters can often resolve unexpected behavior. For example, a tool change issue might be due to an incorrect time parameter.

8. Measurement Comparison: Using test points on printed circuit boards, technicians can measure voltages and waveforms to assess the health of the system. Understanding the function of each test point is essential for accurate diagnosis.

9. Tapping Method: If a fault appears intermittently, it may be due to poor contact or a cold solder joint. Gently tapping the suspected area can temporarily restore functionality, helping identify the issue.

10. Heating Method: Components that degrade over time may fail under certain temperature conditions. Applying heat using a hair dryer or soldering iron can simulate these conditions and trigger the fault for analysis.

11. Principle Analysis: By understanding the system's design and logic, technicians can analyze voltage levels, waveforms, and other characteristics to pinpoint the fault. This method is particularly useful for complex or non-obvious issues.

Other techniques such as the plug-in board method, voltage pull-off method, and open-loop detection can also be employed depending on the situation. In practice, combining multiple methods often leads to the most efficient and accurate resolution of CNC machine tool faults.