The Most Common CNC Machine Issues

Computer numerical control (CNC) machines have revolutionized manufacturing, elevating product quality, operational efficiency, and reliability. The technology is so popular that the CNC machine market size is expected to be worth $140.78 billion globally by 2028, at a compound annual growth rate of 7.1%. These manufacturing powerhouses can experience glitches and other problems like any other technology. Without the correct knowledge, these relatively minor issues can have far-reaching consequences.

The common problems of CNC machines vary from jammed parts to overheating. They require a proactive approach to prevent outcomes like spindle failure, which can grind operations to a halt and result in significant revenue losses. Identifying and addressing issues before they happen and immediately as they arise is often the most efficient and cost-effective way to boost machining uptime.

7 Common Issues With CNC Machines

Common issues with CNC machines can have significant consequences. Errors may seem minor, but if left unidentified, they can cause considerable damage to the tools and machine. These issues can reduce the machine’s service life and impact productivity, leading to replacement costs or extensive downtime. Over time, they result in complete failure.

Identifying and addressing common problems with machine tools boosts tool and machine longevity. Predictive and proactive maintenance also reduces downtime and keeps our machining tools functioning optimally, which improves overall efficiency.

The most common CNC machine issues include:

Code Errors

Computer-driven machines rely on complex code, and programming is one of the most common errors machine operators face. These errors could arise through inputting incorrect variables into the program, setup errors, or a lack of understanding of the different G and M computer codes.

These issues may be challenging to detect, particularly if employees lack experience. Many look to the machine immediately, bypassing the possibility that the problems come from the computer. The wasted time, material, and machine damage can be expensive and slow operations.

Lack of Maintenance

CNC machines consist of many moving mechanical systems and must work to extremely tight tolerances to maintain product quality. The slightest error, wear, or debris can significantly affect machine performance, jamming them or causing permanent damage. Over time, dirt and debris build up, and minor errors become more severe, eventually causing machine failure.

Material shifting during the cutting process, overheating, and noises are common signs that something is wrong with CNC machines. Most often, signs of overdue maintenance include minor machine inaccuracies, such as nonconforming or marginally conforming surfaces, that are not up to the usual standards.

Vibration or Chatter

Vibrations during operation reduce the tool’s life span, affecting its durability and long-term functionality. As chatter and vibrations affect the machine, it becomes less efficient and cost-effective. If operators notice any unusual noises or chatter, identify where the vibration originates from and take the necessary steps to remedy the issue.

However, machines often vibrate long before it is noticeable to the human ear, and modern maintenance practices involve regular monitoring of vibrational and ultrasonic frequencies to identify minor performance deficiencies.

Chuck Fixture Clamping Problems

Lack of attention when clamping the workpiece on the machine is another standard error in CNC machining. Improper clamping can cause issues like misalignment, chatter, or distortion, damaging the machine or workpiece. If the chuck does not grip the workpiece securely, it may need to be replaced. This issue can be more severe than damaged workpieces or tools. Improperly clamped machine parts can lead to accidents and injure operators, impacting the safety of the entire operation.

Incompatible Power Supply

If operators notice machine performance issues, the power supply could be the issue. The power supply must always have the correct voltage for the input side. The output must also work correctly to ensure the machine receives adequate power. Underpowered machines will need to work for longer to achieve the same results and cause tool failure or workpiece damage. Too much power can damage machines or even lead to complete failure.

Improper Tools or Settings

The incorrect cutting tool for the job impacts the quality of the material finish. Watch out for cutter marks, rough edges, or burn marks on the material’s edges and corners. Using the incorrect tools or settings repeatedly causes extensive tool wear. Dull tools and incorrect speed ratios can also result in poor material finishes.


Overheating is a common issue for high volumes and long durations of machining. Machine spindle overheating is often due to the machines not being clean and not having proper airflow. Environmental temperatures can often contribute to machine overheating, which impacts job quality, the tool, and the machine. A typical CNC machine should keep to a consistent temperature range to prevent adverse outcomes.

How to Avoid Common Problems With Machine Tools

Although challenges are sometimes unavoidable when operating complex machinery, supervisors can take specific steps to minimize unnecessary damage and failure. A preventive approach can save time and money, eliminating preventable downtime, repairs, and replacements. Take the following steps to reduce the effects of common errors and maintain machine longevity:

  • Prioritize operator training: Human error is common in manufacturing, whether selecting the wrong tools or making data input errors. Ensure operators are provided with extensive training and access to user manuals and have experienced operators mentor them until they’re familiar with the relevant settings and protocols.
  • Create a preventive maintenance program: CNC machines require regular cleaning and maintenance. Create a detailed maintenance schedule and ensure the team documents any repairs so that the organization has a comprehensive record of each machine’s issues. Operators should inspect machines regularly to ensure adequate coolant levels and identify signs of wear.
  • Conduct a vibration analysis: A vibration analysis allows machine repair specialists to monitor machine vibration data and detect potential issues. It can detect bearing failures, bent shafts, misalignment, loose components, and more. If operators are concerned about vibrations, consult professionals to help identify the root cause.
  • Monitor the environment: Environmental factors are a significant part of efficient CNC machine operation. Monitor the temperature, humidity, noise, and power fluctuations to ensure machines have a productive operating environment.
  • Calibrate the machine: Regular calibration maintains machine accuracy and reliability. Follow manufacturer guidelines and have an expert inspect the machine regularly to address minor issues before they become big problems.

Machine tool issues and operator errors can be costly for operations. Working with experienced and reliable machine tool specialists can mitigate these issues with comprehensive after-sales service and trustworthy guidance for correct settings, programming, and maintenance. These professionals can also advise on whether repairing or replacing equipment is best, boosting uptime and machine longevity.

Avoid Common CNC Machine Issues With Setco

Various factors can cause simple machining issues to escalate into more challenging situations, from incorrect programming to excessive heat and vibration. Keeping spindles, slides, milling heads, and bearings in optimal condition is essential to boost overall productivity and performance.

Setco has been in business since 1912, and as the world’s largest independent rebuilder of machine tool components, we have the skills and experience to manufacture and repair your CNC spindles.

We understand the value of balancing quality and efficiency, so we offer precision spindle inspection and repair services to keep your machines performing optimally. Contact us today to learn more about how we can restore your spindles to OEM specifications or better!

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