What Is the Difference between 3D Printing and CNC Machining?

Ⅰ. The difference between 3D printing and CNC machining

First of all, the injection molding process is different. 3D printing and manufacturing is an additive technology, and CNC machining is a subtractive technology, so they are very different in terms of materials.

1. The difference between CNC machining materials and 3D printing 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 (FDM), 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 processing are all plates, which are plate-like materials. After the length, width, and height of the parts plus wear are measured, the plates of the corresponding size can be cut for processing.

There are more choices of CNC processing materials than 3D printing materials. General hardware and plastic plates can be CNC machined, and the density of molded parts is better than that of 3D printing.

2. The difference in parts of CNC machining and 3D printing due to the different forming 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 stack them up layer by layer/point by point in order, just like building blocks. Therefore, 3D printing can effectively process and produce parts with complex structures, such as hollow parts, while CNC is difficult to realize hollow parts and precision parts.

CNC machining is 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. But, outside right-angle can be achieved by CNC machining. Therefore, for parts with internal right angles, 3D printing processing can be taken into consideration.

Another point is the curved surface. If the surface area of the part is relatively large, it is recommended to choose 3D printing. CNC machining 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.

3. The difference between CNC machining and 3D printing operating software

Most of the 3D printed slicer is easy to operate, even a layman can operate the slicer proficiently in a day or two under professional guidance. Because the slicer is currently optimized to be very simple, the support can be automatically generated, which is why 3D printing can be popularized by 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 part can be produced through many kinds of CNC machining schemes, and 3D printing will only have a small part of the influence on the processing time because of the position, which is relatively objective.

4. The difference between the post-processing of CNC machining and 3D printing

There are not many post-processing options for 3D printed parts, generally including polishing, spraying, deburring, dyeing. The post-processing options for CNC machined parts are varied: in addition to polishing, oil injection, deburring, there are electroplating, silk screen printing, pad printing, metal oxidation, laser engraving, sandblasting and so on.

Ⅱ. Advantages and disadvantages of 3d printing and CNC machining

1. Advantages of CNC machining: CNC belongs to the traditional technology, which is manufactured by subtracting materials by machining. The products produced have good surface effects, with low cost and high precision, since high precision CNC machining is available. It is the current mainstream processing method.

Disadvantages: CNC machining time is long, due to its closed structure, it is not available to process some parts with special structures.

2. The advantages of 3d printing: fast processing speed; closed type can be printed; custom 3d printing services are available.

Disadvantages of 3d printing: the cost of metal and large products is relatively high.