Analyse the difference between cnc machining and 3d printing from multiple perspectives

with regards tocnc machining跟3d printingWhat is the difference in terms of common sense, 3d printing belongs to a kind of additive technology, and cnc processing belongs to a kind of subtractive technology, in terms of materials, 3d printing materials mainly contain liquid resin (SLA), metal powder (SLM), nylon powder (SLS), gypsum powder (full-colour prints), wire (DFM), sandstone powder (full-colour prints), sheet material (LOM) and so on. The materials used for cnc machining are usually sheets, and the length, width, and height of the connected parts and the corresponding losses are measured, and then the corresponding sizes of the sheets are cut out for machining.

Firstly, there exists a situation where 3D printing, the dominant contemporaryMetal 3d printing technologyThere are five main types included, one is nanoparticle jet metal forming (NPJ), the second is laser selective sintering (sls), the third is laser melting and moulding (LMD), the fourth is laser selective melting (SLM), and the fifth is electron beam selective melting (EBM) technology.

1. Nanoparticle Jet Metal Forming (NPJ)

We all know that ordinary metal 3d printing technology is the use of laser melting and laser sintering of metal powder particles, nanoparticle jet metal moulding technology (npj) technology is not in powder form, but in liquid form, the metal in the form of a one-piece is wrapped in a tube and inserted into the 3d printer, at the time of the metal 3d printing, the metal nanoparticles contained in the “iron water” jet moulding. "The advantage is that by using hot water to print the metal, the model is more rounded and can be used as a tool for normal inkjet printing, and when the printing is complete, the build chamber is heated so that the excess liquid evaporates, leaving only the metal behind.

2. Laser selective sintering (sls)

Process device sls the whole is composed of powder cylinder and moulding cylinder, powder cylinder piston rises, powder car will put the powder in the moulding cylinder evenly spread on a layer, the computer according to the circular slicing model to control the laser beam two-dimensional scanning trajectory, selective sintering of solid powder material to form a level of the part, after completing a layer, the work of the piston down a layer of thickness, the laying of the powder system laying on the new powder to control the laser beam to again scanning After completing a layer, the working piston drops one layer, the powder spreading system spreads new powder, and the laser beam is controlled to scan again to sinter a new layer, and so on until the 3D part is formed.

3、Laser Melting and Moulding Technology (LMD)

This technology has many names, different research institutes carry out their own independent research, but also to its independent name, commonly used names are DLF, LENS, DMD, LRF, etc., and SLM is the main difference is that the powder with the help of nozzles convergence to the work of the table above, and the laser convergence to become a point, the powder melting and cooling to get the accumulation of cladding entity.

4. Laser selection melting (SLM)

The basic principle of laser selective melting technology is to design a three-dimensional solid model of the part on a computer with the help of three-dimensional modelling software such as Pro/e, GATIA, UG, etc. The model is then sliced and layered to obtain the contour data of each section. Then, the 3D model is sliced and layered by the slicing software to obtain the contour data of each cross-section. Afterwards, the contour data is used to generate fill scan paths. Based on these fill scan lines, the machine controls the laser beam to selectively melt the layers of powdered metal material and gradually mould them into 3D metal parts. Before the laser beam starts scanning, the powder spreader pushes the metal powder onto the substrate of the moulding cylinder. The laser beam then processes the current layer by selectively melting the powder on the substrate according to the fill scan line of the current layer. Afterwards, the forming cylinder is lowered by one layer thickness and the powder cylinder is raised by a certain thickness distance. The powder spreading device spreads the metal powder on the processed current layer. The machine calls in the data for the next layer of the profile to be processed. This goes on and on, layer by layer, until the entire part is machined.

5. Electron beam melting technology (EBM)

Its process is extremely similar to SLM, the main difference is that the energy source used by EBM is an electron beam. The electron beam output energy of EBM is usually an order of magnitude greater than the laser output power of SLM, and the scanning speed is much higher than SLM, so when EBM is constructed, the whole of the moulding table has to be warmed up, to avoid large residual stresses caused by excessive temperature during moulding.

II. cnc machining centres

CNC machining centre originates from CNC milling machine, it integrates all the functions and processing characteristics of CNC milling machine, the structure of the two is the same, the machining process is quite similar, and, CNC machining centre integrates a variety of machine tool processing functions and machining processes, it can be completed after a clamping multi-processing, such as milling, boring, tapping, drilling and threading, etc. Multi-processing production; Usually, CNC machining centre's Usually, the classification of CNC machining centre mainly includes the following kinds:

1, according to the structure according to the spindle and table relative position for classification;

2、Classified according to the processing procedure;

3. Classify according to the number of control axes;

4, according to the cnc machining centre tool magazine tool change way to classification;

5. Categorise according to the number of benches;

6, according to cnc machining centre machining accuracy to classification;

Third, 3d printing and cnc processing post-processing

cnc machining parts, its follow-up processing can choose more, usually oil spraying, grinding, deburring, silk screen, plating, pad printing, laser engraving, metal oxidation, and sandblasting, etc.; 3d printing parts, its post-processing is relatively simple answer, usually grinding, deburring, oil spraying, but also staining, etc..

Fourth, 3d printing and cnc precision machining processing process comparison:

In terms of programming, 3d printing will go on its own by virtue of its own driver software to calculate the printing time as well as the required consumables, whereas cnc machining requires a professional programme editor plus a machine operator.

2, to see the processing time, because 3d printing is a moulding situation, so when will be less, relatively speaking, cnc precision machining compared to 3d printing, time-consuming will be longer.

3, on the number of processing, for 3d printing, as long as the tray is sufficient, it is able to print out more than one part, and no artificial guard, however, cnc machining centre is usually only able to process one part at a time.

4, from the processing accuracy and success rate, 3d printing accuracy is relatively high, the success rate of printing is also relatively high; cnc machining centre due to the existence of human error, or poor fixture conditions, which may lead to processing failure, however, from the perspective of accuracy, cnc machining centre machining accuracy will be significantly better than 3d printing.

5, on the complexity of the process, 3d printing can be used for processing more complex surfaces and shaped structure of the parts, can be a one-time moulding, cnc can process more complex surfaces together with the shaped structure of the parts, however, need to be divided into many times to carry out programming, disassembly processing.

6, on the practicality of the product, 3 d printing and forming the finished product has the strength of the situation is not high, the finished product also exists not wear-resistant shortcomings, cnc machining centre processed products with high strength advantages, the product also has wear-resistant advantages.

These are the differences between cnc machining and 3d printing, expect to be able to bring you some useful help, Shenzhen HongWeiSheng Precision Technology is dedicated to high-precision cnc numerical control machine tools to carry out external processing work, if you have the demand for precision parts processing, you are welcome to call HongWeiSheng, we will present you with the perfect product solutions and supporting the Technical support.

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