CNC prototyping has high processing precision, which can accurately control product quality and features high production efficiency. It is a commonly used prototyping method in many large prototyping factories. However, there are still differences in the machining accuracy of CNC prototypes. The reasons for this can be analyzed from the following aspects.
1. Dimensional accuracy
This refers to the degree of conformity between the actual size of the processed part and the center of the tolerance zone of the part size. Dimensional accuracy is controlled by dimensional tolerances. Dimensional tolerance is the allowable variation in part size during machining. In the case of the same basic size, the smaller the dimension tolerance, the higher the dimension accuracy.
2. Shape accuracy
Refers to the degree of conformity between the actual geometry of the processed part surface and the ideal geometry. There are six items for evaluating shape accuracy, including straightness, flatness, roundness, cylindricity, and line profile. The shape accuracy is controlled by shape tolerance. The shape tolerances are divided into 12 precision levels except for roundness and cylindricity, which are divided into 13 precision levels. Level 1 is the highest and Level 12 is the lowest.
3. Position accuracy
It is the actual position accuracy difference between the relevant surfaces of the parts after machining. There are eight items for evaluating position accuracy, including parallelism, perpendicularity, inclination, coaxial, symmetry, position, circular runout, and full runout. The position accuracy is controlled by the position tolerance, and the position tolerance of each item is also divided into 12 accuracy levels.
4. Knife: The knife used by the processing machine is generally a tungsten steel knife. After this kind of knife is used several times, the knife will wear out, so there is also an error in the knife.
5. Manual tool setting: If there is a tool setting instrument, there will be no problem in the tool set. However, to save costs, many small prototype factories will choose no tool setting instrument when choosing a machine, and only manual tool setting is required, so there are tolerances in personnel. To ensure the accuracy of the prototyping model, the tool setting instrument is installed on the CNC prototyping equipment, which not only enables accurate tool setting but also greatly improves the work efficiency.
The above are the five aspects that affect the machining accuracy of CNC prototyping. The influence of each aspect will lead to differences in the accuracy of the final prototyping model. Therefore, it is necessary to start with the machining accuracy of each aspect to make the prototyping model that can achieve the best results.