Introduction

CNC (Computer Numerical Control) technology has become an essential tool in modern manufacturing. By combining the power of computer science and engineering manufacturing, CNC technology has dramatically changed the face of manufacturing, bringing efficient, accurate, and reliable production methods.

However, in the manufacturing process, the failure of CNC machines is also a headache for manufacturers, which will significantly reduce production efficiency.

There is no need to panic when there is a problem with the CNC machine, as there are many common issues with CNCs and ways to fix them. This article mainly introduces the most common issues of CNC machines in daily production and how to solve these problems to improve production efficiency.

Common Issues With CNC Machines and How to Fix Them

Any CNC machine will have large and small failures in the operation process; in addition to the problem of the machine itself, human errors are also one of the causes and solutions of machine failure. The following concerns the common causes of the CNC machines, machine failure, and solutions.

1. Machine accuracy problem

Machine accuracy is critical to ensuring finished product quality and consistency in modern manufacturing. Machine accuracy relates to the ability of mechanical devices to perform desired operations precisely. Once the machine has accuracy problems, it will significantly affect the quality of the product.

Continuous use and repetitive machining can cause wear on guides, sliders, and bearings, ultimately affecting the machine’s accuracy and stability.

Temperature changes can cause the expansion and contraction of mechanical components, affecting the machine’s accuracy. For example, temperature changes may cause error accumulation, especially in high-precision processing.

Regular maintenance, temperature compensation technology, and routine machine checks should be implemented to improve accuracy.

1. The implementation of regular machine maintenance is the key to ensuring the normal operation and accuracy of the CNC machine. Maintenance includes lubricating parts, cleaning slides, checking fasteners, etc., to prevent mechanical wear and loosening.

2. Temperature change is an essential factor affecting machine accuracy. Use temperature sensors to monitor ambient temperature and apply temperature compensation technology to correct errors caused by temperature changes.

3. Regular calibration and testing of the machine to ensure the accuracy of its movement and positioning. Verify machine size and position accuracy using precision measuring tools.

2. Tool wear and broken tool problems

Machine tools play a vital role in computer numerical control (CNC) machining machines; they are one of the critical elements to achieving high precision in milling machines and high-efficiency machining machines.

The hardness of the processed material directly affects the wear of the machine tools. When the tool is in contact with a material with higher hardness, the cutting process will lead to increased wear on the rough edges of the tool surface and may even cause the tool to wear faster.

Too high or too low a cutting speed will affect the life of the machine tools. Too high a cutting speed may cause the tool surface temperature to be too high, accelerating wear and fall off. Too low cutting speed may cause the cutting force of the tool to be too large, causing the fracture of the tool.

How to solve the CNC machine tools’ problem? Here are some suggestions:

1. Perform regular tool inspection, including checking the cutting tools’ appearance, the cutting edge’s condition, and the degree of tool wear. Regular inspection detects problems early, and measures can be taken to extend the tool’s service life.

2. According to the hardness of the machining material, tool material, and geometry, select the correct cutting speed, feed speed, and cutting depth. Reasonable cutting parameters can reduce the risk of tool wear and fracture.

3. Choosing a tool coating with high wear resistance, high-temperature resistance, and low coefficient of friction can effectively reduce tool surface wear. These coatings provide additional protection and extend tool and mechanical parts’ life.

4. The automatic tool changer is used on the output side of the CNC machining spindle. During the machining spindle process, when the output wires the tool needs to be switched, the automatic tool changer device will remove the used tool according to the instructions of the CNC program and then select a new tool from the automated tool changer library and install it on the input side of the spindle.

3. Program errors and programming problems

CNC programming has a critical nature in CNC machine machining, and it is necessary to ensure the precision and accuracy of the instructions so that the various CNC machining machines can operate according to the intended path. Any programming error or even an error in a basic function can result in an inaccurate part size, affecting the quality and assembly of the final part.

During the operation of the milling machines, relevant programming needs to be input, and spelling errors, symbol errors, and capitalization problems in programming statements may lead to incorrect interpretation and execution of the program.

A coordinate system’s choice and setting point are critical in CNC programming. The wrong choice or settings of the coordinate system or set of coordinate origins can cause the tool path to differ from the expected, affecting the part’s geometry.

Non-uniform units are also a major cause of programming errors. CNC programming must ensure consistent units are used (e.g., millimeters, inches); otherwise, it may lead to incorrect tool path and dimension calculations.

Solution:

1. Using CNC simulators or validation tools, the written programs are simulated and checked. This can help detect potential equipment interference, path errors, coordinate problems, etc., to ensure the program can be executed correctly in the actual processing.

2. Develop and follow consistent programming specifications and standards, including syntax, coordinate system, cutting parameters, etc. This helps reduce syntax errors and fix coordinate system problems.

3. Proper training of operators sufficiently to equip them with the right programming skills and basic CNC knowledge. Skilled operators are better able to identify and correct potential program errors.

4. Material selection and fixing problems

The choice of materials in CNC machining has an important impact on the final processing results. Improper material selection may lead to processing difficulties, quality problems, and even the inability to complete the processing, so choosing the right material is also critical.

Improper material selection may increase the power supply and the difficulty of cutting. Some materials can be very hard and wear-resistant, resulting in rapid tool wear and reduced processing power supply and efficiency. On the other hand, too fragile materials may be prone to problems such as broken knives and cracks, increasing the power supply loss to CNC machines.

Not choosing the right machining material can lead to increased tool losses and longer processing times, thus increasing processing costs. In addition, the higher procurement cost of certain special materials will also increase the total cost.

The instability of material fixation may cause vibration during cutting, thus affecting the stability of tools and workpieces. Especially in high-speed cutting conditions, vibration may lead to resonance phenomenon, further aggravating the degree of vibration and affecting the machining accuracy and surface quality.

Incorrect material fixation can cause workpieces to shift during CNC machining, leading to increased errors, affecting the part’s size and shape, and reducing machining quality.

How to solve:

1. Different materials have different physical and mechanical properties and are suitable for different processing operations. According to the characteristics and requirements of the required parts, the appropriate material is selected to ensure processing quality and accuracy.

2. Unstable material fixation may cause vibration and movement, affecting machining accuracy. Optimize material fixation methods, using appropriate clamps, fixture positioning, and fasteners to ensure material stability on the machining table.

5. Insufficient cooling and lubrication

Insufficient cooling and lubrication can harm CNC machining, impacting the performance of vital components such as the hydraulic pump and cylinder. Proper cooling and lubrication are important in CNC machining because they can significantly affect machining quality, tool life, and productivity. The cutting process will produce high temperatures; if the temperature is too high, it will lead to thermal expansion of the material, deformation, and rapid tool wear. Proper cooling can maintain the temperature of the cutting area within a reasonable range and reduce problems caused by heat. Cooling and lubrication reduce the friction between the tool and the workpiece, reducing the tool wear rate. The lubrication of the cutting fluid can reduce the cutting force and extend the tool’s service life.

Insufficient power and cooling lubrication can cause the power tool to overheat during cutting. High temperatures will accelerate tool wear, soften tool materials, and may even cause the power tool to fall off, deform, or break.

Inadequate cooling lubrication can result in roughness, burrs, and cutting marks on the machined surface. High temperatures and friction can damage the workpiece’s surface, affecting the final part’s appearance and quality.

Lack of cooling lubrication can increase friction during cutting, resulting in increased cutting forces. This can lead to accelerated tool wear, affect machining efficiency, and may lead to tool breakage.

Insufficient cooling lubrication will accelerate tool wear, resulting in shortened tool life. Frequent tool changes increase production costs and downtime.

Temperature instability may lead to workpiece size changes, resulting in machining errors. Especially in precision machining, temperature changes can lead to dimensional instability and affect part quality.

How can we overcome these problems:

1. Select the appropriate cooling lubricant According to the processing material, cutting task, and process requirements. Different materials and processing needs may require different lubricants, such as cutting oil, fluid, or mixed cooling fats, which can enhance the hydraulic pump and hydraulic cylinder performance.

2. Ensure adequate tool and cutting area coverage by configuring the cooling lubrication system, considering the hydraulic pump and cylinder needs. Adjust spray position settings, pressure, and flow rate for good cooling and lubrication during cutting, maintaining the efficient operation of these hydraulic components.

3. Regularly check the cooling lubricant’s cleanliness, concentration, and performance, as well as the condition of the power supplies. Replace or maintain the system as needed because dirty coolant can reduce effectiveness and affect processing quality and the reliability of power supplies.

6. Operator professional skills

Whether the operator can perform the correct operation also significantly impacts production; skilled operators can correctly set cutting parameters, tool paths, etc., to ensure accuracy and consistency in the processing machining process. They can monitor the machining process and adjust parameters in time to correct possible errors, thereby improving the parts’ geometric accuracy and surface quality. However, once the operator’s skills are insufficient or there are mistakes in the processing process, it may seriously impact the processing quality and production safety.

Inadequate operator skills can lead to CNC programming errors, such as syntax errors, logic problems, etc. This error can lead to incorrect machine movement, affecting parts’ geometric accuracy and surface quality.

Unfamiliar with tool performance and application, the operator may choose an unsuitable tool or the wrong use. The wrong tool selection or use may lead to excessive cutting force, poor surface quality, severe tool wear, and other problems.

Inadequate operator skills may result in incorrect setting of cutting parameters, such as cutting speed, feed speed, spindle speed, etc. Improper cutting parameters may lead to unstable machining processes, part size deviation, etc.

Operators are unfamiliar with quality inspection processes and methods and may neglect to inspect machined parts, which can lead to mistakes at work. This may lead to the quality of the machined parts is not up to standard, affecting the quality of the final product.

Without the skills to identify and troubleshoot faults, operators may not be able to promptly detect and resolve problems in the process, resulting in production stagnation and loss.

Inadequate operator skills can lead to unsafe operating behaviors, such as improper operation and neglect of safety regulations. This can result in accidents and personal injury.

Problem-solving methods:

1. Comprehensive training for operators covering CNC programming, machine tool setup and operation, tool management, equipment quality control, and more. Training can be conducted through internal training, external training institutions, online education, etc.

2. Set up a skill certification system to certify operators who have attained a certain level. Certification can provide incentives to encourage operators to improve their skill level continuously.

3. Establish a mentor system for experienced operators to mentor and train newcomers. This helps newcomers learn and adapt to CNC machine operations more quickly.

4. Encourage experienced operators to share their best practices, including programming tips, tool selection, and program adjustments. This sharing of experience can transfer knowledge and expertise within the team.

5. Conduct regular assessments of operator job skills, identify deficiencies, and provide further training and guidance. The job evaluation results can help to develop a personalized job promotion plan.

Conclusion

CNC machines and technology are crucial in the manufacturing industry by offering automation, precision, and enhanced efficiency, leading to improved production output and product quality. However, addressing common challenges is imperative to ensure the consistent and effective operation of CNC systems. Issues like improper tool selection, program errors, and insufficient cooling lubrication can adversely impact processing quality and efficiency. Manufacturers and operators should maintain a continuous learning and improvement mindset, utilizing training, skills certification, and knowledge sharing to enhance their skills and adapt to the ever-evolving manufacturing landscape. By doing so, CNC machines and technology can reach their full potential, driving ongoing advancements in the manufacturing sector.

This concludes our presentation. Please consider sharing it with your colleagues and peers if you find it valuable. To delve deeper into CNC machining, consider subscribing to receive further insights. Should you encounter any precision machining requirements or related challenges, STCNC stands ready to assist you in finding solutions.