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Explain the introduction and working principles of eight 3D printing technologies

2024-04-12 14:38

3D printing is most commonly used in prototype production, and its ability to quickly produce individual parts can enable ideas to be quickly validated and save costs. The most common 3D printing technologies are SLA, DLP, FDM, etc., but these are not the only types. Below, we will introduce and explain the working principles of these 3D printing technologies.

Stereolithography (SLA)

Stereolithography (SLA) is the original industrial 3D printing process. SLA printers excel in producing parts with high levels of detail, smooth surface finish, and strict tolerances. The high-quality surface finish on SLA parts not only looks beautiful, but also helps with the functionality of the parts - for example, testing assembly fit. It is widely used in the medical industry, with common applications including anatomical models and microfluidics.

Principle: Stereolithography technology is a computer controlled laser beam that uses design data provided by a CAD system to solidify liquid photosensitive resin layer by layer. This layer by layer bonding method combines the planar motion of the laser with the vertical motion of the platform to manufacture a standing object.

Selective Laser Sintering (SLS)

Selective laser sintering (SLS) melts nylon based powders into solid plastics. Due to the SLS components being made of genuine thermoplastic materials, they are durable, suitable for functional testing, and can support movable hinges and buckles. Compared to SL, the parts are more sturdy, but the surface finish is rougher. SLS does not require a supporting structure, so it can use the entire construction platform to nest multiple parts into a single construction - making it suitable for a higher number of parts than other 3D printing processes. Many SLS components are used for prototype design and will one day be injection molded.

Principle: The laser beam is selectively sintered under computer control based on the layered cross-sectional information. After one layer is completed, the next layer is sintered. After all sintering is completed, excess powder is removed to obtain a sintered part.

Inkjet technology (PolyJet)

PolyJet is another plastic 3D printing process, but there is a turning point. It can manufacture parts with multiple attributes, such as color and material. Designers can use this technology to create prototypes of elastomers or encapsulated parts. If your design is a single rigid plastic, we recommend that you stick to using SL or SLS - this is more economical. However, if you are creating prototypes for wrap molding or silicone rubber design, PolyJet can eliminate the need to invest in tools early in the development cycle. This can help you iterate and validate your design faster and save you money.

Principle: Each layer of photosensitive polymer material is immediately solidified with ultraviolet light after being sprayed, creating a completely solidified model that can be immediately transported and used without the need for post solidification. Gel shaped support materials specially designed to support complex geometry can be easily removed by hand or by spraying water.

Digital Light Processing (DLP)

Digital light processing is similar to SLA because it uses light to cure liquid resin. The main difference between these two technologies is that DLP uses digital light projector screens, while SLA uses ultraviolet lasers. This means that the DLP 3D printer can image the entire construction layer at once, thereby improving construction speed. Although often used for rapid prototyping, the higher throughput of DLP printing makes it suitable for small batch production of plastic parts.

Principle: The principle is to pass the light source emitted by the light through a condensing lens, homogenize the light, and then use a Color Wheel to divide the light into RGB three colors (or more colors). The colors are then projected onto the DND by the lens, and finally imaged through the projection lens.

Multi jet melting (MJF)

Similar to SLS, Multi Jet Fusion also uses nylon powder to manufacture functional components. MJF does not use lasers to sinter powders, but instead uses inkjet arrays to apply the molten agent onto the nylon powder bed. Then the heating element passes through the bed layer to fuse each layer. Compared to SLS, this leads to more consistent mechanical properties and improved surface smoothness. Another benefit of the MJF process is that it accelerates construction time, thereby reducing production costs.

Principle: The working method of this technology is very interesting: first lay a layer of powder, then spray flux, and at the same time, spray a detailing agent to ensure the precision of the printed object edges, and then apply a heat source on top. This layer is considered completed. And so on, until the 3D object is completed.

Melt Deposition Modeling (FDM)

Melt deposition molding (FDM) is a common desktop 3D printing technology for plastic parts. The function of FDM printers is to extrude plastic filaments layer by layer onto the construction platform. This is an economically efficient and fast method for making physical models. In some cases, FDM can be used for functional testing, but this technology is limited due to the relatively rough surface finish and insufficient strength of the parts.

Principle: The FDM process involves melting and extruding plastic wires through high-temperature nozzles. The wires are stacked, cooled, and solidified on a platform or processed product, gradually accumulating a solid layer by layer.

Direct Metal Laser Sintering (DMLS)

Metal 3D printing has opened up new possibilities for the design of metal parts. It is usually used to reduce metal and multi-component components into single components or lightweight components with internal channels or hollowing features. DMLS can be used for prototyping and production, as the density of parts is as dense as those produced using traditional metal manufacturing methods such as machining or casting. Creating metal components with complex geometric shapes also makes them suitable for medical applications where part design must mimic organic structures.

Principle: By using high-energy laser beams controlled by 3D model data to locally melt the metal matrix, while sintering and solidifying powder metal materials and automatically stacking layers, dense geometric shaped solid parts are generated.

Electron beam melting (EBM)

Electron beam melting is another metal 3D printing technology that uses an electron beam controlled by an electromagnetic coil to melt metal powder. During the construction process, the printing bed is heated and in a vacuum state. The temperature at which the material is heated is determined by the material used.

Principle: It is to import the three-dimensional solid model data of the parts into the EBM device, and then lay a thin layer of fine metal powder in the working chamber of the EBM device. By using the high-density energy generated by the deflection and focusing of the high-energy electron beam at the focal point, the scanned metal powder layer generates high temperature in local small areas, causing the metal particles to melt. The continuous scanning of the electron beam will cause the small metal melt pools to fuse and solidify, connecting to form linear and planar metal layers.