Analysis of CNC machining process quality control points
Compared with the traditional conventional machine tool processing, CNC machining has the advantages of process concentration, automation, high accuracy, softness, etc., can effectively complete the shape of complex, small batch, multi-species type of parts processing, is the modernization of the manufacturing of the development of an important means of technology application. Analyzing the quality control system structure of the CNC machining process is conducive to sorting out the operation process links of the CNC process, and clarifying the key links of quality control of the CNC machining process.
Moreover, by analyzing the main problems of quality control of the CNC machining process, we can summarize the difficulties that need to be overcome in the process of quality management, and then take effective measures to strengthen the quality control of the CNC machining process and improve the quality level of CNC machining.
CNC machining process quality control system structure
1. CNC machining process operation flow
CNC machining process operation flow is shown in Table 1. CNC machining step by step operation flow is based on process quality control theory and the corresponding method, CNC machining process quality can reflect the results of the machining process with the design, technology and operational goals fit.
Measurement and supervision through the production plan to meet the standard rate, product on-time delivery rate, quality loss rate, the number of rework, scrap rate, the initial inspection pass rate, quality loss rate, and other indicators.
The so-called quality control of the CNC machining process, the essence of which is to control the fluctuation of indicators in the CNC machining process within the prescribed range using effective supervision, measurement, and control.
Combined with the process links in Table 1, it can be found that the quality control of the CNC machining process is mainly reflected in the following aspects, respectively, measurement, materials, information, methods, personnel, and machine tools, which are closely related to the CNC machining process links.
2. CNC machining process quality control system structure
For CNC machining process quality control, the first task is to carry out quality planning for the actual situation, quantitative CNC machining process indicators, including design, process, production, and operation of various aspects of the indicators, through the digital way of presenting the quality characteristics of the CNC machining process, and then combined with the digital quality characteristics of the formation of the key CNC process quality control objectives, to better control, supervise and evaluate the quality of the CNC machining process. Process quality.
In addition, we also need to use statistical data collection and analysis tools, dynamic collection of quality characteristics of CNC machining process data, the actual data and key process quality control standards for comparison and analysis, the results of the analysis of the development of quality evaluation and optimization program: Finally, the quality evaluation and optimization program to the production of CNC machining processes at each stage of the production, to achieve systematic, comprehensive quality improvement and Feedback quality control for the production process.
CNC machining process quality control system is shown in Table 2.
CNC machining process quality controls existing problems
1. CNC machining process program to be improved
CNC machining process due to its high technology intensity, complex production processes, and other characteristics, resulting in CNC machining process quality management and control face many challenges. The current stage of the CNC machining process program has certain shortcomings, such as the processing process design is not compact enough, and the lack of systematic and process-oriented machining process program design ideas, resulting in the actual application of CNC machining process program often appearing as fragmented, resulting in parts in the flow process through multiple links, frequent positioning, and assembly is not only time-consuming, but also makes the parts of the dimensional accuracy and tolerance of shape and position. Difficult to ensure that the probability of damage and deformation of the parts, so that the processing quality of the parts, precision, etc. are affected.
2. Production preparation is too sloppy
With the continuous development of science and technology in China, the field of CNC machining and technology has gradually matured, but China’s CNC machining process planning and program design has not formed a unified standardized system, resulting in a certain degree of irrationality, unscientific, non-standard practices in the actual CNC machining process, pulling down the quality of the process of CNC machining and enhance the probability of occurrence of CNC machining problems.
In addition, due to the lack of standardization, a unified standardization system, can not provide effective guidance for enterprises to dynamically adjust the parameters of the CNC program for different parts, hindering the full play of the technical potential of CNC machine tools and tool performance.
Specifically manifested in the traditional CNC machining process ideas in the program design are still dominant, making it difficult for the relevant technical staff to monitor and accurately regulate the parameters in real-time, which directly affects the accuracy of product manufacturing and processing speed.
Although CNC technology is regarded as the key to the transformation and upgrading of enterprises, the backward production technology and rough programming impede its effectiveness in practical applications, further restricting the overall improvement of the level of CNC machining technology.
CNC machining process quality control points and measures
1. Improve the CNC machining process program, clear the process production route
Whether it is traditional machine tool processing or CNC machine tool processing, the actual operation of the process needs to strictly follow the principle of coordination and unity, to avoid the emergence of security and standardization problems in the processing.
However, in terms of CNC machine tools, their automation, and a high degree of digitalization, there is a more sophisticated process design, design content specific and clear features, which also causes CNC machining needs CNC machining process programs to have a high degree of precision to ensure that CNC machining process in the automation of the operation during the process can always be accurate, and then to achieve the purpose of guaranteeing the quality of the CNC machining process.
CNC machining process program is mainly embodied in the CNC programming, if the process program is unreasonable, incomplete problems will trigger the phenomenon of CNC machining errors, which in turn reduces the quality of CNC machining. Therefore, if you want to effectively improve the quality and efficiency of the CNC machining process, you can do the following aspects.
First, the initial analysis and planning. In the CNC machining operations should be a full, comprehensive, in-depth understanding of the characteristics of the parts to be processed and processing needs, such as parts structure, material hardness, machining accuracy, and other conditions, and as a basis for setting up the initial machining process and process flow, to ensure that CNC machining process to meet the current demand for CNC machining of parts.
Second, trial production and optimization. The actual machining process may be due to tool hardness, machining, and other issues and errors, so the a need for formal CNC machining operations before the product of small batch trial production.
Through trial production, you can verify the feasibility of the initial planning of the CNC machining process, rationality, according to the trial results of the necessary adjustments to optimize the use of detailed CNC machining data to analyze each step of CNC machining, select the most suitable machining strategy and tooling, to ensure that not only to meet the technical requirements but also in the cost and productivity to achieve a balanced state, which in turn form both scientific and economical CNC Process flow of CNC machining.
Finally, quality control and improvement. After finalizing the CNC machining process program, through continuous monitoring of CNC machining process data to achieve dynamic control of CNC machining process quality, the need for real-time and accurate monitoring of CNC machining production process output quality data, such as machining accuracy, efficiency, and scrap rate.
The use of professional quality management methods to assess and analyze such data to accurately grasp the quality of the current status of the machining process, on this basis, to identify and intervene in the CNC machining process may have an impact on the quality of the key factors, and through timely adjustments and optimization, continue to improve the quality of the entire CNC machining process.
This phase mainly emphasizes the importance of data-driven quality control and continuous optimization of the CNC machining process, to achieve the overall improvement of the quality of the CNC machining process.
2. Scientific preparation of the CNC program to ensure the quality of machining process
The CNC program controls the normal operation of CNC machine tools based on CNC machine tools through the implementation of a pre-written CNC program to automatically complete the processing of parts, through the CNC program in the relevant parameters of the changes in the adjustment can be achieved according to the pre-determined design, machining order to guide the action of the CNC machine tool target.
Therefore, the scientific nature of the CNC program, rationality, feasibility, and other elements will be directly related to the quality of the entire CNC machining process and the quality of the final product. If there are defects in the machining process or the product needs to be further optimized, it can be realized by modifying and optimizing the CNC program in conjunction with the actual situation.
To ensure that the CNC machining process manipulated by the CNC program has a certain degree of accuracy and stability, the following points should be made.
First, emphasize the accuracy, completeness, and comprehensiveness of CNC programming. Combined with the specific characteristics and structure of the parts, to build an accurate parts model, and at the same time to build the parts model as the basis for setting the programming coordinate system.
In addition, the relevant technical personnel in the preparation of CNC programs should also take into account the tool path, machine tool characteristics, CNC machining process safety, and other factors, to avoid the occurrence of tool cutting frequency being too high or too low, resulting in increased tool wear, machining accuracy is not enough and other issues.
Secondly, the scientific arrangement of the CNC machining process. The CNC machining process including the selection of tool type, clear route, set cutting parameters, etc., needs to combine the characteristics of parts and components products and processing standards, reasonable arrangements for CNC machining in the operating procedures, and the corresponding CNC program parameters to ensure that the product production process and machining procedures in an orderly and standardized division.
For example, according to the hardness of the parts, structural characteristics and tool type, and reasonable arrangement of tool route, different tool routes should be set with different cutting parameters to ensure the accuracy of CNC machining.
Finally, in the process of CNC machining should pay close attention to the actual working status of the tool, by observing the working status of the tool to determine the operation of the CNC machine tool and CNC programming reasonability, prevention console, workpiece, tool, the fixture may appear between the bad interaction, such as physical collision, mutual interference, overcutting (over-processing), undercutting (under-processing) and so on, once such undesirable problems need to be immediately Adjust the parameters of the CNC program, to maximize the precise control ability of the CNC program through dynamic, refined CNC process management, to ensure the safety and efficiency of the entire machining process.
3. Select the appropriate quality control methods, improve the quality management process of CNC machining
In the CNC machining process quality control, the quality management and control methods can be used in a variety of ways, including statistical methods, but also involves qualitative and quantitative analysis techniques, through the selection of appropriate quality control methods to improve the quality of CNC machining management process, thereby effectively improving the quality of CNC machining process.
First of all, statistics-related quality management methods, such as hierarchical method, collection, and grouping to analyze the data generated by different CNC machining processes; the arrangement of diagrams, specific analysis for specific problems, to identify the main problems and causes: histograms, to show the distribution of data.
Through these statistical methods can be more comprehensive, intuitively identify and solve the quality problems in the CNC machining process, and then continuously improve the quality management process of CNC machining.
Secondly, the combination of qualitative and quantitative quality management methods, such as matrix data analysis, matrix diagram method, process decision-making procedure diagram method, affinity diagrams, correlation diagrams, etc., can achieve the effect of precise organization and classification of the problem, show the logical relationship between the factors, multi-dimensional analysis of the problem, multi-dimensional visualization of the relationship between the factors, etc., to help the relevant technical personnel to understand the current problems in the process of NC machining in a more in-depth way and the specific Causes, and to optimize the CNC machining process and make relevant decisions to provide a reliable basis.
It should be noted that in the actual selection of the CNC machining process quality control methods, should be combined with the actual production data of CNC machining and personnel skills level, with high efficiency, convenience, flexibility, and stability as the goal of comprehensive consideration. Scientific and reasonable selection of quality management control methods to ensure the steady progress of CNC machining steps and improve the quality of parts.
In short, in the CNC machining process quality management should be a comprehensive use of a variety of analytical tools and techniques to achieve effective control of the quality of the CNC machining process and product quality continuous improvement.
4. Construct a CNC machining process simulation check, show the CNC machining process
Simulation check belongs to the core technology in CNC machining, but also one of the important measures in the quality control of CNC machining process. Simulation is mainly divided into geometric simulation and physical simulation of two kinds.
(1) Geometric simulation. Geometric simulation mainly relies on digital, information-based CNC machining simulation software to achieve, while integrating three-dimensional imaging and virtual reality technology, a dynamic, clear, complete reproduction of the CNC machining process of each step, details, and the actual dynamics of the CNC machine tool.
The application of geometric simulation can not only accurately and completely check the actual operation of CNC machine tools in the process of potential geometric collision risk, but also verify the accuracy and reasonableness of the tool route to further enhance the quality and safety of the CNC machining process, and effectively avoid potential losses and hidden dangers.
(2) Physical simulation. The main role of physical simulation is to explore and analyze the various physical phenomena that occur in the CNC machining process. With the continuous maturation of physical simulation technology, its scope of application is more and more widely used in modernization, digital production and processing enterprises. Physical simulation technology based on the dynamics of the simulation optimization system can effectively improve production efficiency, for fine adjustment of milling parameters to provide reliable data support.
In addition, there are some enterprises with the help of meta-analysis technology, for complex precision parts cutting process physical simulation check and management, through scientific and reasonable finite element analysis method, detailed simulation of the parts in the process of CNC machining of the physical changes: including but not limited to the parts of the processing of the load changes, the initial state of the stress material properties, environmental conditions, etc., through the observation and analysis of the parts of the CNC By observing and analyzing the physical changes during CNC machining, we can accurately grasp the programming parameters, structural properties and machining characteristics of CNC machining.
Compared with geometric simulation, physical simulation is more suitable for the machining of parts with high precision, complex shape and large scale, which provides an effective means of checking the quality control of CNC machining process.
Conclusion
CNC machining is the key to the modernization and development of the machinery manufacturing industry and the core technology driving force, and its effective application can not only overcome the small batch, high-precision and structural complexity of the parts processing problems, but also ensure the high stability and efficiency of the machining process, and effectively reduce the cycle time of the workpiece processing.
However, the CNC machining process is very complex and complicated, covering from process planning, programming, and tool selection to the actual machining, testing, and other closely linked process links, any one process link omission may have an impact on product quality.
Therefore: the quality control of the CNC machining process is particularly important, we need to seriously analyze the problems of the CNC machining process, to take effective quality control measures to ensure the quality of machining.