The term 3D is a popular technology in recent years, such as 3D film, display, scanning and 3D printing technology. Today, we will discuss what the 3D printing technology is. 3D printing technology is to divide the 3D model of an object into several layers through layered software in the computer, and then sinter or stick materials such as plastics, metals and even biological tissue active cells on a plane according to layered graphics through 3D printing equipment, and finally form an object layer by layer.
Features of 3D printing technology: short production cycle, personalized manufacturing, diverse production materials, relatively low production costs, and wide application fields.
According to the characteristics of 3D printing technology and the materials used, we can divide it into five categories: photosensitive curing molding, melt deposition molding, selective laser sintering, layered solid manufacturing, and finally 3D printing technology.
Photocuring takes liquid photosensitive resin as the raw material. Under the control of computer, the UV laser scans the liquid resin point by point to generate photopolymerization reaction, and so on until the curing and molding of the whole part are completed.
Layered entity manufacturing: according to the layered geometric information of temporary buildings, cut foil and paper, etc., and bond the obtained layers into three-dimensional entities.
Selective laser sintering: It is a 3D printing method that uses laser selective layer by layer sintering to fix the powder and superpose to generate 3D solid parts of predetermined shape.
Melt deposition molding: melt the thermoplastic material wire into liquid through the extrusion head of the heater, and the computer controls the extrusion head to accurately move along the contour of each section of the part, so as to take advantage of the melt at a fixed rate.
Metal 3D printing technology is the most advanced and optimal potential technology in 3D printing technology today. It can be divided into three types: selective laser melting, laser near net forming technology, and electron beam melting.
At present, there are two main factors restricting the development of 3D printing technology: printing materials and equipment. At present, 3D printing materials mainly include engineering plastics, photosensitive resins, rubber materials, photosensitive materials and ceramic materials. Its shape is generally powder, filiform, lamellar and liquid.
Engineering plastics have excellent strength, hardness, impact resistance, durability and aging resistance. Photosensitive resin is composed of polymer monomer and prepolymer, which can immediately cause polymerization reaction to complete curing under certain wavelength of ultraviolet light. Rubber material, which has a variety of levels of elasticity. Its hardness, elongation at break, tear resistance and tensile strength make it very suitable for applications requiring anti-skid or soft surfaces. Ceramic materials, with high strength, high hardness, high temperature resistance, low density, good chemical stability, corrosion resistance and other excellent characteristics, are widely used in aerospace, automotive, biological and other industries. Metal materials: metal powder materials for 3D printing mainly include titanium alloy, stainless steel, aluminum alloy, superalloy, etc. In addition, there are precious metal printing materials. Among all materials, titanium alloy is particularly valued because of its low density, high strength, corrosion resistance and high melting point. It is an ideal aerospace material, especially suitable for using laser 3D printing technology. Stainless steel is currently the cheapest and cheapest 3D printing material, which is often used for 3D printing of jewelry, functional components, etc. Superalloys have become the main 3D printing materials in the aviation industry due to their high strength, stable chemical properties, difficult forming and high cost of traditional processing technologies.
The reason why metal materials are difficult to print is that the melting point of metal is very high, which involves a variety of physical processes such as solid-liquid phase transition, surface diffusion and heat conduction of metal. The problems to be considered include whether the crystal structure formed is good, impurities and void size. In addition, rapid heating and cooling will also cause large residual stress in the test piece.