What is the impact of planer tool wear on machining accuracy?

What is the impact of planer tool wear on machining accuracy?
In the field of mechanical processing, planers, as a common processing equipment, are widely used in various plane, groove and other processing tasks. As a key component directly involved in cutting, the state of planer tool has a vital impact on the processing quality. Among them, tool wear is a factor that cannot be ignored. It not only affects the service life of the tool, but also directly affects the machining accuracy. This article will deeply explore the impact of planer tool wear on machining accuracy, aiming to provide valuable reference for relevant technical personnel.

1. Common forms of planer tool wear
During use, planer tools will be affected by cutting force, cutting heat, and friction with workpieces and chips, resulting in wear. Common tool wear forms include the following:
Front cutter wear: During the cutting process, strong friction and high pressure are generated between the chips and the front cutter face, resulting in gradual wear of the front cutter face. This wear is usually manifested as a crescent-shaped wear in front of the cutting edge. As the wear intensifies, the sharpness of the cutting edge decreases, the cutting force increases, and the cutting temperature increases, thereby affecting the machining accuracy.
Flank wear: The flank of the tool contacts and rubs against the machined surface of the workpiece. Long-term cutting will cause flank wear. Flank wear will increase the gap between the tool and the workpiece, reduce the positioning accuracy of the cutting edge, and lead to deviations in the machining dimensions.
Cutting edge wear: The cutting edge is the part of the tool that directly contacts and cuts the workpiece. Because it bears the greatest cutting stress and cutting heat, the cutting edge usually wears faster. Cutting edge wear will lead to the passivation of the cutting edge, increase the heat generated during the cutting process, increase the cutting force, and intensify the cutting vibration, which seriously affects the surface quality and dimensional accuracy of the workpiece.
Tool surface wear: In addition to the above-mentioned main wear forms, the surface of the tool may also be worn due to chemical reactions with the media in the surrounding environment (such as moisture and oxygen in the air). Although this wear is relatively slow, it will also have a certain impact on the performance of the tool during long-term use.

2. The specific impact of planer tool wear on machining accuracy

1. Impact on machining dimensional accuracy
The wear of the planer tool will cause the geometry of the cutting edge to change, thereby affecting the cutting thickness and cutting depth during the cutting process. For example, the wear of the back face will increase the gap between the tool and the workpiece. During the cutting process, the tool is prone to sinking or offset, resulting in deviations in the size of the workpiece after processing. In addition, the wear of the cutting edge will make the cutting edge blunt, the deformation of the chips generated during cutting will increase, and the cutting force will also increase, which will cause the tool to produce elastic deformation in the cutting direction, resulting in inaccurate processing dimensions.

2. Impact on the surface quality of the processing
The wear of the tool will directly affect the formation and discharge of chips during the cutting process, and thus affect the surface quality of the workpiece. When the tool is severely worn, the sharpness of the cutting edge decreases, the friction between the chips and the front face during the cutting process intensifies, and the chips are prone to curling and breaking, which will not only increase the cutting force and cutting heat, but also cause the chips to scratch the processed surface of the workpiece during the discharge process, resulting in increased surface roughness. In addition, the wear of the cutting edge will also cause cutting vibration, causing periodic collisions between the tool and the workpiece, further deteriorating the surface quality of the workpiece.

3. Impact on the accuracy of processing shape
In planing processing, the wear of the tool may cause deviations in the shape of the workpiece after processing. For example, when the cutting edge of the tool is unevenly worn, the force of the tool on the workpiece during the cutting process is unevenly distributed, which can easily cause the workpiece’s processing shape to be distorted or deformed. In addition, tool wear may also cause uneven distribution of cutting heat, causing local thermal expansion of the workpiece during the cutting process, further affecting the accuracy of the processing shape.

4. Impact on processing position accuracy
The wear of the planer tool will also affect the positioning accuracy of the tool, thereby affecting the processing position accuracy. For example, when performing multi-step cutting or tool change operations, if the position of the cutting edge changes due to tool wear, the subsequent cutting process will not be able to be performed accurately according to the predetermined position, resulting in deviations in the processing position. In addition, tool wear may also cause the increase of the transmission error and positioning error of the machine tool, further reducing the accuracy of the processing position.

3. Factors affecting planer tool wear
1. Tool material
The performance of the tool material directly affects its wear resistance and wear resistance. Commonly used planer tool materials include high-speed steel, cemented carbide, etc. High-speed steel has good toughness and strength, but its hardness and wear resistance are relatively low, and it is easy to wear during the cutting process. Carbide tools have higher hardness and wear resistance, and can maintain good cutting performance at higher cutting speeds, but they are more brittle and are prone to chipping or fracture under impact loads. Therefore, choosing the right tool material is of great significance for reducing tool wear and improving machining accuracy.

2. Cutting parameters
Cutting parameters include cutting speed, feed rate and cutting depth, which have a significant impact on tool wear. Higher cutting speeds will rapidly increase cutting temperature and accelerate tool wear; larger feed rates will increase cutting force and the contact area between the cutting edge and the workpiece, resulting in increased cutting edge wear; and larger cutting depths will cause the tool to bear greater cutting stress, which is prone to plastic deformation and wear of the tool. Therefore, reasonable selection of cutting parameters and optimization of cutting conditions based on factors such as workpiece materials and tool materials are one of the key measures to slow down tool wear and ensure machining accuracy.

3. Workpiece materials
The mechanical properties of the workpiece material, such as hardness, strength, and toughness, as well as its chemical affinity with the tool material, will affect tool wear. Workpiece materials with higher hardness will cause the tool to bear greater cutting force and wear during the cutting process, accelerating tool wear; while materials with greater toughness are prone to entangled chips, increasing the friction between chips and tools, and causing tool wear to increase. In addition, there is a strong chemical affinity between some workpiece materials and tool materials, which is easy to produce diffusion wear during the cutting process, further reducing the service life of the tool.

4. Cooling and lubrication conditions
Good cooling and lubrication conditions can effectively reduce the cutting temperature, reduce the friction between the tool and chips and workpieces, and thus slow down the wear of the tool. In planing processing, the reasonable selection of the type and concentration of coolant, as well as the use of appropriate lubrication methods (such as spray lubrication, oil immersion lubrication, etc.), can significantly improve the service life and processing accuracy of the tool. However, if the cooling and lubrication are insufficient and the cutting temperature is too high, the tool wear will rapidly increase, and may even cause damage to the tool and burns to the workpiece.

IV. Detection and preventive measures for planer tool wear

1. Tool wear detection method
In order to timely detect the wear of the tool and ensure the processing accuracy, an effective tool wear detection method is required. Common detection methods include:
Visual inspection: Observe the wear of the cutting edge, front face and back face of the tool with the naked eye to determine whether the tool needs to be replaced. This method is simple and intuitive, but has limited ability to identify minor wear or early wear characteristics.
Measuring tool measurement: Use measuring tools such as micrometers and calipers to measure wear parameters such as the blunt radius of the cutting edge and the width of the wear band on the back face of the tool to determine the degree of wear of the tool. This method has high accuracy, but requires downtime and requires high measurement skills of the operator.
Cutting force monitoring: Monitor the changes in cutting force during the cutting process through sensors installed on the machine tool or tool. When the tool is worn, the cutting force usually increases, so the wear of the tool can be determined by setting a threshold of the cutting force. This method can achieve real-time monitoring, but it needs to be equipped with corresponding sensors and data acquisition systems, which is costly.
Cutting temperature monitoring: Use equipment such as infrared thermal imagers to monitor the temperature changes in the cutting area. Tool wear will cause the cutting temperature to rise, so the wear of the tool can be indirectly judged by monitoring the temperature change trend. This method has the advantages of non-contact and real-time monitoring, but it is greatly affected by environmental factors, and it is necessary to reasonably select the monitoring position and parameters.
Acoustic emission monitoring: Monitoring is based on the acoustic emission signals generated during tool wear. Impact, friction, etc. generated during tool wear or cutting will trigger acoustic emission signals. The wear state of the tool can be judged by analyzing the characteristics of these signals. This method has high sensitivity and real-time performance, but signal processing and feature extraction are relatively complex and require professional knowledge and technology.

2. Preventive measures for tool wear
In order to reduce the wear of planer tools, extend the service life of tools, and improve processing accuracy, the following preventive measures can be taken:
Reasonable selection of tool materials and geometric parameters: According to the workpiece material and processing requirements, select tool materials with high hardness and good wear resistance, and optimize the tool geometry, such as increasing the front angle and back angle, to reduce cutting force and cutting temperature, and slow down tool wear.
Optimize cutting parameters: According to factors such as tool material, workpiece material and machine tool performance, reasonably select cutting parameters such as cutting speed, feed rate and cutting depth, avoid excessive or low cutting speed and excessive cutting amount to reduce tool wear.
Improve cooling and lubrication conditions: Use appropriate coolant and lubrication methods to ensure sufficient cooling and lubrication during the cutting process, reduce cutting temperature and friction, and slow down tool wear. At the same time, regularly check the operation of the cooling system to ensure the stability of the flow and pressure of the coolant.
Improve tool installation accuracy: Ensure the installation accuracy of the tool on the machine tool spindle to avoid cutting imbalance and vibration caused by improper tool installation, thereby reducing tool wear.
Regularly maintain and service tools: Regularly inspect, clean and maintain the tool to promptly detect and deal with early wear or damage of the tool, keep the tool in good condition, and extend its service life.

V. Conclusion
The wear of planer tools has many effects on machining accuracy, including machining dimensional accuracy, surface quality, shape accuracy and position accuracy. The main forms of tool wear are rake face wear, flank face wear, cutting edge wear and tool surface wear, while factors such as tool material, cutting parameters, workpiece material and cooling and lubrication conditions will affect the wear rate of the tool. In order to ensure machining accuracy, effective detection methods are needed to detect tool wear in a timely manner, and prevent and slow tool wear by rationally selecting tool materials, optimizing cutting parameters, improving cooling and lubrication conditions, and strengthening tool maintenance. In actual production, various factors should be considered comprehensively to formulate reasonable machining processes and tool management strategies to improve the efficiency and quality of planer machining and reduce production costs.