First of all, 3D printing is an additive technology, and CNC machining is a subtractive technology, so they are very different in terms of materials.
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 (LOM) and many more. Liquid resins, nylon powders and metal powders account for the vast majority of the market for industrial 3D printing.
The materials used for CNC machining are all pieces of plates, that is, plate-like materials. By measuring the length, width, height and wear of the parts, the corresponding size plates are cut for processing. There are more choices of CNC machining materials than 3D printing. General hardware and plastic sheets can be CNC machined, and the density of molded parts is better than 3D printing.
2. Differences in parts due to molding principles
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 pile them up layer by layer/bit by bit in order, just like building blocks Same. Therefore, 3D printing can effectively process parts with complex structures, such as hollow parts, while CNC is difficult to process hollow parts.
CNC machining is subtractive manufacturing. Through various tools running at high speed, the required parts are cut out 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, which must be realized by wire cutting/sparking and other processes. Outside right angle CNC machining is no problem. Therefore, parts with inner right angles can be considered for 3D printing.
There is also the surface. If the surface area of the part is relatively large, it is recommended to choose 3D printing. CNC machining of the surface is time-consuming, and if the programming and operator experience is not enough, it is easy to leave obvious lines on the parts.
3. Differences in operating software
Most of the slicing software for 3D printing is easy to operate, even a layman can operate the slicing software proficiently in a day or two with professional guidance. Because the slicing software is currently very simple to optimize, and supports can be automatically generated, which is why 3D printing can be popularized to individual users.
CNC programming software 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.
Because the programming is very complicated, a component can have many kinds of CNC processing solutions, while 3D printing only has a small impact on the processing time and consumables because of the placement position, which is relatively objective.
4. Differences in post-processing
There are not many post-processing options for 3D printed parts, generally grinding, oil injection, deburring, dyeing, etc.
There are various post-processing options for CNC machined parts, in addition to grinding, oil injection, deburring, electroplating, silk screen printing, pad printing, metal oxidation, laser engraving, sandblasting and so on.