Analysis Report on the Causes of Surface Pitting in Precision CNC Machining
In the process of precision CNC machining,the surface pitting is a common problem that can not be ignored,and its causes involve multiple dimensions,which will have a significant impact on the machining quality and production efficiency.The following is an in-depth analysis of the possible causes of this problem.
I.Material issues
Material surface quality
The surface of raw materials used in precision CNC machining may have congenital defects,such as tiny cracks,bubbles and various impurities.In the process of machining,these potential defects will be magnified by cutting force,thermal stress and other factors,and then exposed to the machined surface,eventually forming pits.
Material properties
Different materials have unique physical properties such as hardness,toughness,thermal conductivity,and coefficient of thermal expansion.These properties will have different effects on the generation and transfer of cutting force and cutting heat in the process of machining,and then affect the quality of the machined surface,and become the potential inducement of pitting.
II.Tools and Cutting Parameters
Tool wear
In the continuous cutting operation,the tool will inevitably wear.The geometric shape of the cutting edge of the worn tool changes,and the cutting force generated during cutting will become unstable.This unstable cutting force acts on the machined surface,which can easily lead to pitting.
Improper setting of cutting parameters
Cutting parameters,including cutting speed,feed rate and cutting depth,play a key role in controlling the machining process.If these parameters are not set reasonably,such as cutting speed is too fast,feed rate is too large or cutting depth is too deep,it may lead to a sharp increase in cutting force,a rapid rise in cutting temperature,and then pitting on the machined surface.
III.Processing environment and conditions
Cutting fluid problem
Cutting fluid plays a vital role in precision CNC machining.If the cutting fluid is mixed with impurities,precipitates or bubbles,it will interfere with the normal lubrication and cooling function of the cutting fluid,affect the cutting effect,and cause pitting on the machined surface.In addition,the parameters such as concentration,temperature and flow rate of cutting fluid should also be strictly controlled within the appropriate range to ensure its best performance.
Accuracy and stability of machine tool
The accuracy and stability of the machine tool is the basis to ensure the processing quality.The geometric accuracy of the machine tool,such as the straightness of the guideway,the rotation accuracy of the spindle,as well as the motion accuracy and stability,all have a decisive impact on the machining accuracy.If the key components such as the guide rail and screw rod of the machine tool are worn or loosened,it will lead to the deviation of the processing position and eventually form pits on the processing surface.
IV.Process design
Clamping and positioning mode
The clamping and positioning mode of the workpiece in the machining process is directly related to the stability of the workpiece in the cutting process.If the distribution of clamping force is uneven or the positioning is not accurate,the workpiece is prone to vibration or offset under the action of cutting force,resulting in pitting on the machined surface.
Routing and Sequence
The design of the process route and the arrangement of the processing sequence also have an important impact on the processing quality.Unreasonable process route or improper processing sequence may lead to processing stress concentration,uneven cutting allowance and other problems,and then lead to pitting on the processing surface.
V.Other factors
Skill level of operators
The skill level of precision CNC machining operators plays a direct and decisive role in the quality of machining.Operators with insufficient skills are prone to make mistakes in cutting parameter setting,tool selection and process monitoring,which leads to pitting.
Equipment maintenance and service
Regular and comprehensive maintenance of the equipment,timely inspection and replacement of vulnerable parts,and keeping the equipment clean and accurate are important measures to ensure the stable operation of the equipment and reduce pitting.If the equipment maintenance is not in place,the performance of the equipment will be reduced and the risk of pitting will be increased.
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