3D printing is an additive manufacturing technology. The printed products are accumulated on a plane and accumulated layer by layer. CNC machining is a subtractive manufacturing technology. The raw material is a whole plate. According to the characteristics of the product, the plate is processed to carve off the excess material. To make the same object, 3D printing wastes less material. The technology only needs to accumulate material in the part of the printed product, and there is no waste in other parts. In CNC machining, the excess sheet parts need to be removed and the removed parts are usually not recycled.

Different processing materials

CNC machining is mainly composed of square plates, which are divided into CNC plastic machining and CNC metal machining. CNC machining has more than 20 years of experience in China, and its technology is relatively mature. Materials suitable for CNC machining are relatively common compared with 3D printing technology.

However, the materials for 3D printing need to be divided by specific 3D printing technologies. For example, SLA technology materials in 3D printing of Qile Shouban are mostly resin. The materials of SLS technology are wax powder and plastic powder. FDM materials are generally thermoplastic materials, such as wax, ABS, nylon, etc. Filamentous materials cover most types of products made on the market.

Differences in the structure of the machining model

3D printing materials are superimposed layer by layer, and 3D printing can process complex curved surfaces and structural replication parts, forming at one time. CNC machining of parts with complex curved surfaces and heterogeneous structures requires step-by-step programming, disassembly and processing, and later pasting with chemical glue, thus affecting the overall performance consistency of the model.

Because CNC machining relies on gongs and knives to continuously rotate plates to remove excess materials. When making complex curved surfaces and heterogeneous structure models, manual replacement of tools and fixtures is required to complete the machining, which has a great impact on the loss of precision and cannot be completed by some thin and light samples. Moreover, since the gong knife is round and cannot make a 90-degree right angle, models with right angles or oblique angles cannot be processed.

However, CNC machining is an open processing environment, with a large proportion of manual intervention, which requires manual turning over of the plate, and the forming size is larger than that of 3D printing. For relatively large, relatively simple structure, CNC machining has an advantage.

The difference between processing speed and cost

3D printing can process multiple parts at a time, directly import 3D data maps, and guide the data through calculation. Computer data can be directly transmitted to the machine for printing. During this period, personnel are not required to be on duty, and only constant temperature and humidity are required throughout the day in the operation room.

The drawings of CNC machining need to be identified manually and the processing program is written. Due to the long programming time and only one part can be processed at a time, the fixture design needs to be replaced by the operator during the processing. The processing time and labor cost are 2-3 times that of 3D printing.

3D printing can easily make complex structural models; CNC is more advantageous in material selection and large-scale model making. The two processing methods are complementary to each other.