1. Differences in materials
3D printing materials mainly include liquid resin (SLA), nylon powder (SLS), metal powder (SLM), gypsum powder (full-color printing), sandstone powder (full-color printing), wire (DFM), sheet material (LOM) and many more. Liquid resin, nylon powder and metal powder occupy most of the market for industrial 3D printing. The materials used for CNC machining are all plates, which are plate-like materials. By measuring the length, width, and height of the parts + wear, the plates of the corresponding size are cut for processing. There are more choices of CNC machining materials for sheet metal than 3D printing. General hardware and plastic sheets can be CNC machined, and the density of the formed parts is better than that of 3D printing.
2. Differences in parts due to the forming principle
As we mentioned earlier, 3D printing is a kind of additive manufacturing. Its principle is to cut the model into N layers/N multi-points, and then stack them up layer by layer/point-by-point in order, just like building blocks. same. Therefore, 3D printing can effectively process and produce parts with complex structures, such as hollow parts, while CNC is difficult to process hollow parts. Hollow CNC machining is a subtractive manufacturing, through various high-speed tools, cutting out the required parts according to the programmed tool path. Therefore, CNC machining can only process rounded corners with a certain radian, but cannot directly process inner right angles. It must be achieved through processes such as wire cutting/sparking. Outside right-angle CNC machining is no problem. Therefore, parts with internal right angles can be considered for 3D printing processing. There is also a curved surface. If the surface area of the part is relatively large, it is recommended to choose 3D printing. CNC machining of the curved surface is very time-consuming, and if the programming and operator experience is not enough, it is easy to leave obvious lines on the parts. No wonder some people say that 3D printing uses cake flour to form a cake, while CNC cuts a big cake into small cakes. This is really simple and easy to understand.
3. Differences in operating software
Most of the slicing software for 3D printing is easy to operate. Even a layman can be proficient in operating the slicing software within one or two days of professional guidance. Because the slicing software is currently optimized to be very simple, the support can be automatically generated, which is why 3D printing can be popularized by individual users. The CNC programming software for slicing effect is much more complicated and requires professionals to operate it. People with zero basic knowledge generally need to learn about half a year. In addition, a CNC operator is required to operate the CNC machine. The more commonly used ones are UG, MASTERCAM, CIMATRON, and domestically produced fine carvings. There is still a certain degree of difficulty in learning these software. The programming of UG operation page is very complicated, and a part can have many kinds of CNC machining schemes, while 3D printing only has a small effect on the processing time because of the position, which is relatively objective.
4. Differences in post-processing
There are not many post-processing options for 3D printed parts, generally polishing, spraying, deburring, dyeing and so on. The post-processing options of CNC machined parts are varied, in addition to polishing, oil spraying, deburring, as well as electroplating, silk screen printing, pad printing, metal oxidation, laser engraving, sandblasting and so on. There is a sequence of hearing the truth, and there is a specialization in the surgery industry. CNC machining and 3D printing have their own advantages and disadvantages. Choosing the right processing technology has a vital influence on your prototype project.