As we all know, in the process of machining, each product is installed by several parts, so the processing quality of parts is the foundation of the whole machine, which directly affects the performance and life of the machine. Many factors will affect the final processing quality of parts. Today, I would like to share with you what are the main factors that affect the machining accuracy of CNC parts.
The machining accuracy of CNC parts is mainly affected by the following aspects:
1. Machine error
Machine tool error refers to the manufacturing error, installation error and wear of the machine tool. It mainly includes the guide error of the machine tool guide, the rotation error of the machine tool spindle, and the transmission error of the machine tool transmission chain.
2. Machining principle error
The error of machining principle refers to the error caused by using approximate blade profile or approximate transmission relationship for machining. The error of machining principle mostly appears in the machining of threads, gears and complex surfaces.
3. Adjustment error
The adjustment error of the machine tool refers to the error caused by inaccurate adjustment.
4. Residual stress in the workpiece
Occurrence of residual stress: residual stress occurred in the process of rough embryo production and heat treatment; Residual stress caused by cold straightening; Residual stress caused by cutting.
5. Environmental impact of processing site
There are often many fine metal chips on the processing site. If these metal chips exist on the positioning surface or the orientation of the positioning hole of the part, the processing accuracy of the part will be affected. For high-precision processing, some metal chips that are too small to be visible will affect the accuracy. This influencing factor will be identified, but there is no very effective method to eliminate it, and it often relies heavily on the operator's operation method.
6. Manufacturing error and wear of fixture
The error of fixture mainly refers to the manufacturing error of positioning element, tool guide element, indexing mechanism, clamp details, etc; After the fixture is installed, the relative dimension error between the working surfaces of the above components; Wear of the working surface of the fixture during use.
7. Tool making error and wear
The influence of tool errors on machining accuracy varies according to the types of tools.
8. Stress deformation of process system
The process system will deform under the action of cutting force, clamping force, gravity and inertia force, and then destroy the mutual orientation relationship of the components of the adjusted process system, leading to the occurrence of processing errors and affecting the stability of the processing process. The machine tool deformation, workpiece deformation and the total deformation of the process system shall be considered first.
9. Thermal deformation of process system
In the process of machining, the process system is heated and deformed due to the heat generated by internal heat sources (cutting heat, friction heat) or external heat sources (ambient temperature, thermal radiation), and then the machining accuracy is affected. In large workpiece machining and precision machining, the machining error caused by thermal deformation of the process system accounts for 40% - 70% of the total machining error.
