How to quickly understand CNC machining part drawings?

First of all, we must figure out what is the purpose of understanding a CNC machining part drawing.

In fact, this is the entry point for us to look at the drawings.  There is only one purpose for looking at the machining drawings - to do machining.

For machining involves the selection and configuration of the following processing elements:

1.  Selection of processing equipment;

2.  Processing tool selection;

3.  Processing fixture selection;

4.  Processing program and parameter setting;

5.  Selection of quality inspection tools;

1.  Drawing elements that affect the selection of processing equipment

A. The structure and shape of the parts. The processing equipment includes turning, milling, planing, grinding, boring, drilling, etc. For example, we choose to use lathes for shaft parts, and milling machines and boring machines for box parts. These skills It is a common sense skill, and it is easy to learn.

B. The material of the part. The material of the part should be considered the balance between the rigidity of the processing and the processing accuracy. Of course, there are also some considerations in terms of physical and chemical properties. At the same time, the release of stress and so on must also be taken into account. It is a university question. 

C. The processing accuracy of the parts, the processing accuracy is often guaranteed by the accuracy of the equipment itself, but it also has a great relationship with the processing method.  For example, the surface roughness of the milling machine is relatively poor compared to the grinding machine.  If the surface is rough For workpieces with high precision requirements, grinding machines are usually considered.  In fact, there are many types of grinding machines, such as surface grinders, cylindrical grinders, centerless grinders, guide rail grinders, etc., which must match the structure and shape of the parts.

D. The processing cost of parts. A good tool means high efficiency and good quality, but it also consumes a lot of cost and relies more on processing equipment; although poor tools have low efficiency and poor quality control, the cost It is relatively controllable and more applicable to processing equipment. Of course, in the process of high-precision processing, the increase in processing costs cannot be controlled.

2. Drawing elements that affect the selection of processing fixtures

A. The structure and shape of the part. Generally speaking, the design of the fixture is completely based on the structure and shape of the part. Even most of the fixtures are dedicated, which is also an important factor restricting the automation of processing.  In fact, in our In the process of building a smart factory, the biggest trouble in the process of automation is the automation and universal design of fixtures, which is one of the biggest challenges for design engineers.

B. The processing accuracy of the parts.  Generally speaking, the higher the processing accuracy, the more precise the fixture requirements are.  This fineness is reflected in various aspects such as rigidity, precision and structural processing, and it must be a special fixture, a general universal fixture, There must be a compromise in terms of machining accuracy and structure, so there is a big trade-off here.

C. Although the process design of the parts does not reflect the process flow on the drawings, the manufacturability can be judged according to the drawings.  This is a very test for process engineers, and many operators with processing experience can also read it on the part drawings.  In terms of craftsmanship, this is also the embodiment of the skills of part design engineers.

3. Drawing elements that affect processing procedures and parameter settings

A. The structure and shape of the part, because this determines the choice of machine tool equipment, and then also determines the choice of processing methods and processing tools, which will affect the preparation of processing programs and the setting of processing parameters.

B. The machining accuracy of the parts, the machining program and the machining parameters are ultimately to serve the machining accuracy of the parts, so the machining accuracy of the parts ultimately needs to be guaranteed by the machining program and machining parameters.

C. The technical requirements of the parts. In fact, in addition to reflecting the structural characteristics, geometric accuracy and shape tolerance of the parts, many drawings also involve specific technical requirements, such as quenching treatment, paint treatment, stress relief treatment, etc., which will also involve to changes in processing parameters.

4. Drawing elements that affect the selection of quality inspection tools

A. Who will judge the structure and shape of parts and the processing quality of parts? Quality inspectors, as authorities, can certainly do this work, but they do it based on corresponding testing tools and instruments. The quality inspection of many parts is not simple. It can be judged by the naked eye.

B. The processing accuracy of parts and high-precision parts quality inspection must be completed through professional and high-precision quality inspection equipment, such as three-coordinate measuring instrument, laser measuring instrument, etc. The processing accuracy requirements of drawings directly determine the inspection Tool configuration standards.

C. The technical requirements of parts, corresponding to different technical requirements and quality requirements, need to be equipped with different inspection equipment to do corresponding quality inspections. For example, we can use calipers, rulers, three-coordinates, etc. to detect the length, and we can use it to detect the hardness. Hardness tester, we can use roughness tester or roughness comparison block and so on to test the surface finish.