3D printing technology is an intelligent manufacturing technology that dates back to1980s, which integrates machinery, computers, numerical control, and materials. The basic principle of 3D printing is to obtain two-dimensional cross-section information by the layered processing of the three-dimensional substantial parts, and achieve the sustanital part or prototype by  building up layer by layer with the point, line, or surface used as the basic unit. 3D printing is different from traditional subtractive (such as cutting) and iso-material (such as forging) manufacturing methods, and it can realize the manufacture of complex structural parts that traditional methods cannot or are difficult to achieve. 3D printing can greatly reduce the processing procedures and shorten the processing cycle, so it has received extensive attention from scientific researchers all over the world.

Ⅰ. The development of 3D printing service

3D printing service was first applied to the rapid manufacturing of various prototypes, so it was also called Rapid Prototyping (RP) in the early days. Due to the limitation of material types, the early 3D printing technology mostly used organic polymer materials, whose mechanical and chemical properties were most difficult to meet the needs of practical applications. With the development of material technology and equipment technology, the need to apply this technology to the manufacture of terminal components is becoming more and more urgent for 3D printing service providers. Therefore, not only higher requirements are put forward for 3D printing equipment, but the requirements for various properties of 3D printing materials are also increasing.

Ⅱ. The material for 3D printing service

3D printing materials are an important material basis for 3D printing technology, and its performance largely determines the overall performance of the formed parts. With the increasingly in-depth application of 3D printing services in various fields, the safety of 3D printing materials has become a hot topic. We can discuss the current popular polymer materials and metal materials.

1. Polymer material

Polymer materials for 3D printing mainly include photosensitive resins, thermoplastics, and hydrogels. Paper, starch, sugar, chocolate, etc. can also be included in the category of polymer materials, but the scope of temporary applications in the industrial manufacturing field is not very common. Take photosensitive resin as an example. It is one of the earliest materials used in 3D printing and is suitable for SLA 3D printing service. Its main component is a small molecule resin (prepolymer, monomer) that can undergo polymerization reaction, which is added with photoinitiators, polymerization inhibitors, leveling agents, and other additives, and can be exposed to specific light (usually ultraviolet light)  for polymerization reaction to achieve curing. Photosensitive resin is not a new material. Photoresist, photocurable coatings, photocurable inks, etc., with similar working principles have been widely used in electronic manufacturing, holographic imaging, adhesives, printing, medical and other fields.

2. Metal materials for 3D printing

According to Wohlers Report, the metal 3D printing industry has developed significantly. As a very important material in 3D printing, metal materials have prosperous application prospects in industries such as automobiles, vowin.cn/' target='_blank'>molds, energy, aerospace, and biomedicine. Since metal materials are mostly directly used in industrial rather than verification, the safety guarantee during the application process is more worthy of discussion.