40 HD moving pictures, understand the principle of 3D printing in seconds!

-Reprinted from 3D Printing World
This paper mainly introduces the five technologies of SLA, CLIP, 3DP, PolyJet and FDM, as well as NPJ,

1. SLA（StereoLithography）

SLA, or light curing molding technology, refers to the use of ultraviolet light irradiation liquid photosensitive resin polymerization reaction, to layer by layer curing and generating three-dimensional solid molding method, SLA preparation of the workpiece scale precision is high, is the earliest commercial 3D printing technology.

SLA Process Engineering:

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2. CLIP 

CLIP, the continuous liquid interface extraction technology, is a revolutionary 3D printing technology developed by Carbon 3D on the basis of SLA technology, which increases the speed of 3D printing by 100 times!

CLIP is projected from the bottom to cure the photosensitive resin, and the part that does not need to be cured forms a dead zone by controlling oxygen to inhibit the light curing reaction and maintain a stable liquid area, thus ensuring the continuity of curing.

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↑ Oxygen inhibits the light curing process ↑

↑ Light Curing Dead Zone Demonstration ↑

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3. 3DP（Three-DimensionalPrinting）

3DP is a three-dimensional printing rapid prototyping technology, which is close to traditional two-dimensional inkjet printing. Binder is sprayed from the nozzle (color binder can print color parts), and powder on the platform is bonded and molded, usually using gypsum powder as the molding material. 3DP technology currently has two main applications: full-color 3D printing and sand casting.

The following is Exone's sand casting process with 3DP technology:

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4. PolyJet

PolyJet is polymer injection technology, its molding principle is similar to 3DP technology, but the injection is not adhesive but light curing resin, after the injection is completed by ultraviolet radiation curing molding.

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The PolyJet adopts an array nozzle, and even different materials can be sprayed at the same time to achieve simultaneous printing of multiple materials and multi-color materials.

↑ Array Sprinkler Working Process ↑

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5. FDM（FusedDeposition Modeling）

FDM is the melting lamination technology, which uses high temperature to melt the material, extrude it into filaments through the print head, and accumulate and form on the component platform. FDM is the simplest and most common 3D printing technology, usually applied to desktop-level 3D printing equipment.

Here's how FDM technology works:

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↑ Layer-by-layer printing process ↑

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Metal 3D printing technology can be directly used for rapid prototyping and manufacturing of metal parts. It has broad industrial application prospects and is the key development of 3D printing technology at home and abroad. Here are five metal 3D printing principles: NPJ, SLM, SLS, LMD and EBM.

6. NPJ（Nano Particle Jetting）

NPJ technology is a metal 3D printing molding technology developed by Israeli company Xjet. Compared with ordinary laser 3D printing molding, NPJ technology uses nano liquid metal to deposit molding in an inkjet manner. The printing speed is 5 times faster than ordinary laser printing, and has excellent precision and surface roughness.

The following is the Xjet device working process:

↑ Metal particle refinement ↑

↑ Distribution of metal particles in droplets ↑

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↑ Liquid phase discharge process ↑

↑ The parts after sintering ↑

7. SLM（Selective Laser Melting）

SLM, or selective laser melting forming technology, is currently the most common technology in metal 3D printing forming. It uses fine focusing light spots to quickly melt preset metal powder to directly obtain parts with arbitrary shapes and complete metallurgical bonding, and the resulting manufacturing density can reach more than 99%.

The laser galvanometer system is one of the key technologies of SLM. The following is a working diagram of SLM Solution's galvanometer system:

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↑ Laser transmission ↑

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In the process of metal 3D printing, because the parts are usually more complex, the support material needs to be printed, and the support needs to be removed after the parts are completed, and the surface of the parts is treated.

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8. SLS（Selective Laser Sintering）

SLS is a selective laser sintering technology, similar to SLM technology, the difference is that the laser power is different, usually used for 3D printing of polymer.

The following is the process of SLS to prepare plastic parts:

↑ Model Layered Slice ↑

↑ Removal of parts ↑

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SLS can also be used to make metal or ceramic parts, but the resulting parts have low density and require post-densification before they can be used.

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9. LMD（Laser Metal Deposition）

LMD is laser cladding forming technology. The technology has many names. Different research institutions independently study and name it independently. Common names include LENS, DMD, DLF, LRF, etc. The biggest difference from SLM is that its powder is gathered on the worktable through nozzles, converged with laser at one point, and the powder is melted and cooled to obtain the accumulated cladding entity.

The following is the working process of LENS technology:

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↑ Build process ↑

10. EBM(Electron Beam Melting)

EBM is electron beam melting technology, and its process is very similar to SLM, except that the energy source used by EBM is electron beam. The electron beam output energy of the EBM is usually an order of magnitude larger than the laser output power of the SLM, and the scanning speed is much higher than that of the SLM, so the EBM needs to preheat the whole molding table during the construction process to prevent the excessive temperature during the molding process from causing large residual stress.

The following is the EBM process:

↑ Overall preheat ↑

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↑ Change of powder during melting ↑