3D printing (3DP) is a type of rapid prototyping technology that constructs objects based on digital model files using powdery metals or plastics and other adhesive materials through a layer-by-layer printing method.
3D printing is typically realized using digital technology material printers. It is commonly used in mold manufacturing, industrial design, and other fields to create models, and has gradually been used for the direct manufacturing of certain products, resulting in components printed using this technology. This technology has applications in jewelry, footwear, industrial design, architecture, AEC (Architecture, Engineering, and Construction), automotive, aerospace, dentistry, medical industries, education, geographic information systems, civil engineering, firearms, and other fields.
Ordinary printers used in daily life can print flat items designed on a computer, while the so-called 3D printers operate on a fundamentally similar principle; the only difference is the printing materials. Ordinary printers use ink and paper, while 3D printers contain various “printing materials” such as metals, ceramics, plastics, and sand, which are actual raw materials. After connecting the printer to a computer, the printer can layer the “printing materials” based on computer control, ultimately transforming the blueprint from the computer into a physical object.
1. Engineering Plastics
Engineering plastics refer to industrial plastics used for industrial parts or shell materials, characterized by excellent strength, impact resistance, heat resistance, hardness, and aging resistance. Engineering plastics are currently the most widely used type of 3D printing material, commonly including ABS, PC-type materials, PLA, and nylon materials.
2. Photosensitive Resin
Photosensitive resin refers to ultraviolet (UV) resin, composed of polymer monomers and prepolymers, with a light (UV) initiator added. Under specific wavelengths of ultraviolet light (2500–300nm), it can immediately trigger a polymerization reaction to complete curing. Photosensitive resin is generally liquid and can be used to create high-strength, high-temperature resistant, waterproof materials.
3. Rubber Materials
Rubber materials possess characteristics of various levels of elastic materials, with hardness, elongation at break, tear strength, and tensile strength making them very suitable for applications requiring non-slip or soft surfaces. 3D printed rubber products mainly include consumer electronics, medical devices, and automotive interiors, tires, gaskets, etc.
4. Metal Materials
In recent years, 3D printing technology has gradually been applied to the manufacture of actual products, with metal material 3D printing technology developing particularly rapidly. In the defense sector, developed countries in Europe and America place great importance on the development of 3D printing technology, investing heavily in research, and 3D printed metal components have always been a focus of research and application. The metal powders used in 3D printing generally require high purity, good sphericity, narrow particle size distribution, and low oxygen content. Currently, the main metal powder materials used in 3D printing include titanium alloys, cobalt-chromium alloys, stainless steel, and aluminum alloys, as well as precious metal powders such as gold and silver used for jewelry printing.
5. Ceramic Materials
Ceramic materials possess excellent properties such as high strength, high hardness, high-temperature resistance, low density, good chemical stability, and corrosion resistance, with widespread applications in aerospace, automotive, and biomedical industries. However, due to the hard and brittle characteristics of ceramic materials, processing them into shape is particularly difficult, especially for complex ceramic parts that require molds for shaping. Mold processing is costly and time-consuming, making it difficult to meet the ever-evolving demands of product updates.
6. In addition to the 3D printing materials introduced above, currently used materials also include colored gypsum, artificial bone powder, cellular biological materials, and sugar, among others.
3D printing materials are generally linked to specific processes; choosing different materials determines the process, which in turn dictates the limitations imposed by the process, such as dimensional accuracy, minimum details, and wall thickness. Conversely, if the required dimensional accuracy, minimum details, and wall thickness of the target finished product are known, it can also determine the available 3D printing materials.
1. SL Process Forming Material: Photosensitive resin composite materials
2. LOM Process Forming Material: Ceramics, paper materials
3. SLS Process Forming Material: Polymer powder materials, paraffin powder materials, ceramic powder materials
4. LOM Process Forming Material: Ceramics, paper materials
5. FDM Process Materials: Filament materials, FDM ceramic materials, wood-plastic composite materials, FDM support materials
The design process for 3D printing involves first modeling with computer modeling software, then “slicing” the completed 3D model into layered cross-sections, guiding the printer to print layer by layer.
The standard file format for collaboration between design software and printers is the STL file format. An STL file uses triangular facets to approximate the object’s surface. The smaller the triangular facets, the higher the generated surface resolution. PLY is a 3D file generated by scanning, and the VRML or WRL files it generates are often used as input files for full-color printing.
The printer reads the cross-section information in the file, using liquid, powder, or sheet materials to print these sections layer by layer, and then bonds the layers together in various ways to create a solid object.This technology is characterized by its ability to create almost any shape of object.
The thickness of the printed cross-sections (i.e., the Z direction) and the resolution in the plane direction (i.e., the X-Y direction) are calculated in dpi (dots per inch) or micrometers. The typical thickness is 100 microns (0.1 mm), while some printers, such as the ObjetConnex series and 3D Systems’ ProJet series, can print layers as thin as 16 microns. The plane direction can achieve resolutions similar to those of laser printers. The diameter of the “ink drops” produced is typically between 50 and 100 microns. Traditional methods for manufacturing a model usually take several hours to days, depending on the size and complexity of the model. In contrast, 3D printing technology can reduce this time to a few hours, although this depends on the printer’s performance and the size and complexity of the model.
Traditional manufacturing techniques, such as injection molding, can produce polymer products in large quantities at lower costs, whereas 3D printing technology can produce relatively small quantities of products more quickly, flexibly, and at lower costs. A desktop-sized 3D printer can meet the needs of designers or concept development teams for model manufacturing.
The resolution of 3D printers is sufficient for most applications (curved surfaces may appear rough, resembling jagged edges), and higher-resolution items can be obtained by the following method: first print a slightly larger object with the current 3D printer, then lightly sand the surface to achieve a smooth “high-resolution” item.
Some technologies can print using multiple materials simultaneously. Some technologies also require supports during the printing process, such as when printing objects with overhangs, where easily removable supports (such as soluble materials) are needed.
Source:Material Museum
Editor:Lai Fan
Review:Publicity Department