3D printing is based on the design of three-dimensional models, which are then layered by layer through the 3D printing equipment to increase the material used to manufacture three-dimensional products; this layer-by-layer stacking forming technology is also known as “additive manufacturing.”

3D printing is a set of digital modeling technology, electromechanical control technology, information technology, materials science and chemistry, and other fields of cutting-edge technology in the integrated

technology, known as the core technology of the ‘Third Industrial Revolution’.

Compared with traditional manufacturing technology, 3D printing does not have to make molds in advance, does not have to remove a large amount of material in the manufacturing process, and does not have to go through the complex forging process to get the final product, so it can achieve structural optimization, material savings, and energy savings in production.

3D printing technology is suitable for new product development, rapid single-piece and small-batch parts manufacturing, manufacturing of complex shaped parts, mold design, and manufacturing, etc., but also suitable for the manufacture of difficult-to-machine materials, shape design checking, assembly inspection, and rapid reverse engineering, etc. Therefore, the 3D printing industry, with more and more foreign attention, will become the next broad prospect for developing the sunrise industry.

At present, 3D printing has been applied to product prototypes, mold manufacturing, art and creative products, jewelry production, and other fields; it can replace these areas that rely on the traditional fine machining process; 3d printing can be to a large extent, enhance the production of efficiency and precision, in addition to bioengineering and medicine, construction, clothing, and other fields, the introduction of 3D printing technology has also opened up a broader space for its development.

At present, the United States, Europe, and Japan are standing in the 21st-century manufacturing competition at the strategic height of rapid prototyping technology, which has invested a lot of research, so that 3D printing technology has been rapidly developing.

In the field of national defense, Europe and the United States developed countries attach great importance to the application of 3D printing technology, and invested heavily in the development of additive manufacturing metal parts, in particular, vigorously promote the application of additive manufacturing technology in the manufacture of titanium alloys and other high-value material parts.

Material is an important fundamental of 3D printing but also the bottleneck of the current constraints on its development. Here is a brief introduction to the current status of the development of 3D printing materials and the problems that exist.

3D printing materials

3D printing materials are an important material basis for developing 3D printing technology. Materials development determines whether 3D printing can have a wider range of applications. At present, 3D printing materials mainly include engineering plastics, photosensitive resins, rubber materials, metal materials, and ceramic materials, etc., in addition to colorful gypsum materials, artificial bone powder, cell biological raw materials, as well as sugar and other food materials have been used in the field of 3D printing.

3D printing of these raw materials is specifically for 3D printing equipment and process and research and development, and ordinary plastics, gypsum, resin, etc., there is a difference: its material development determines whether 3D printing can have a wider range of applications. The shape of the material is generally powder, filament, laminated, liquid, etc. Usually, according to the type of printing equipment and different operating conditions, powdered 3D printing material particle size of 1 ~ 100μm and maintaining good powder flow generally require the powder to have a high degree of sphericity.

1.Engineering plastics

Engineering plastics are used as industrial parts or shell materials. They are excellent plastics in terms of strength, impact resistance, heat resistance, hardness, and aging resistance. Engineering plastics are currently the most widely used class of 3D printing materials, including common Acrylonitrile Butadiene Styrene (ABS) class materials, Polycarbonate (PC) materials, nylon materials, etc.

ABS material is a Fused Deposition Modeling (FDM, fused deposition modeling) rapid prototyping process commonly used in thermoplastic engineering plastics. With high strength, good toughness, impact resistance, and other advantages, the normal deformation temperature of more than 90 ℃ can be machined (drilling, tapping threads), painted, and electroplated.

 

ABS material has a variety of colors, such as ivory, white, black, dark grey, red, blue, rose red, etc., in the field of automotive, home appliances, and consumer electronics, there is a wide range of applications.

PC material is a true thermoplastic material with all the characteristics of engineering plastics: high strength, high-temperature resistance, impact resistance, and bending resistance and can be used as the final parts. Sample parts made of PC materials can be directly assembled and used in the transportation and home appliance industries. PC materials have a single color, only white.

Still, its strength is about 60% higher than that of ABS materials, and it has super engineering material properties, which are widely used in consumer electronics, home appliances, automotive manufacturing, aerospace, medical equipment, and other fields.

Nylon fiberglass is a white powder; compared with ordinary plastics, its tensile and bending strength have been enhanced, the heat distortion temperature and modulus have been increased, the shrinkage of the material is reduced, but the surface becomes rougher, the impact strength is reduced, and the heat distortion temperature of the material is 110 ° C. The material is mainly used in automobiles, home appliances, and consumer electronics.

PC-ABS material is one of the most widely used thermoplastic engineering plastics; PC-ABS has the toughness of ABS and the high strength and heat resistance of PC materials, mostly used in the automotive, home appliance, and telecommunications industries.

The strength of prototypes made using this material with FORTUS equipment is about 60% higher than that of parts made using traditional FDM systems, so PC-ABS can print thermoplastic parts, including conceptual models, functional prototypes, manufacturing tools, and final parts.

Polycarbonate-ISO (PC-ISO) is a hygienically certified white thermoplastic material with high strength that is widely used in the pharmaceutical and medical device industries for surgical simulation, cranial repair, dentistry, and other specialized applications.

Because it has all the properties of PC, it can also be used in the food and pharmaceutical packaging industry, making samples that can be used as conceptual models, functional prototypes, manufacturing tools, and final parts.

Polysulfone (PSU)- based materials are amber-colored and have a heat deflection temperature of 189 degrees Celsius. They are the strongest, most heat-resistant, and most corrosion-resistant thermoplastic materials and are commonly used as final components in the aerospace, transportation, and healthcare industries. PSU-based materials offer a direct digital fabrication experience with stable performance and can achieve stunning results when used with FORTUS equipment.

2.Photosensitive resins

Light-sensitive resins, i.e., Ultraviolet Rays (UV) resins, are composed of polymer monomers and prepolymers to which light (ultraviolet) initiators (or photosensitizers) are added. Under the irradiation of a certain wavelength of ultraviolet light (250~300nm), the polymerization reaction can be caused immediately to complete the curing.

Photosensitive resins are generally liquid and make high-strength, high-temperature-resistant, and waterproof materials. Currently, the research of photosensitive materials 3D printing technology is mainly the United States 3DSystem company and Israel Obiect company, common photosensitive resin Somos Next material, resin Somos 11122 material, Somos 19120 material and epoxy resin.

Somos Next is a new, white, PC-like material with very good toughness, which meets the performance of nylon materials made by selective laser sintering (SI.S, selective laser sintering) but with better precision and surface quality.

Parts made from Somos Next have the best rigidity and toughness to date, while retaining the Components made from Somos Next materials offer the best rigidity and toughness to date while maintaining the precision, dimensional accuracy, and aesthetic appeal of light-cured, three-dimensional molding materials for automotive, home appliance and consumer electronics applications.

Somos 11122 material looks more like real transparent plastic. It has excellent water resistance and dimensional stability and offers a wide range of engineering plastics-like properties, including ABS and PBT, which make it suitable for use in automotive, medical, and electronic products.

Somos 19120, a pink material, is a casting material that can be molded to directly replace the wax film prototype for precision casting. This avoids mold development risk and reduces cycle time, with low ash retention and high precision.

Epoxy resin is a casting-friendly laser rapid prototyping resin; it has very low ash content (800 ℃ when the residual ash content <0.01%), can be used for fused silica and alumina high-temperature shell system and does not contain heavy metals antimony, can be used for the manufacture of extremely precise rapid casting molds.

3.Rubber-based materials

Rubber materials have a variety of levels of elastic material characteristics. These materials have hardness, elongation at break, tear strength, and tensile strength, so they are very suitable for the requirements of non-slip or soft surface applications. 3D printing of rubber products is mainly used in consumer electronics, medical equipment, automotive interiors, tires, gaskets, and so on.

4.Metal materials

In recent years, 3D printing technology is gradually applied to the manufacture of actual products, in which the 3D printing technology of metal materials is developing particularly rapidly; in the field of national defense, Europe and the United States developed countries attach great importance to the development of 3D printing technology, at the expense of investing huge sums of money to research, and 3D printing of metal parts and components has always been a key focus of research and application.

3D printing of metal powders is used to meet the general requirements of high purity and good spherical degree; the metal powder used in 3D printing generally requires high purity, good sphericity, narrow particle size distribution, and low oxygen content.

The application metal powder materials used in 3D printing are mainly titanium alloys, cobalt-chromium alloys, stainless steel, aluminum alloys, etc., and gold, silver, and other precious metal powder materials used for printing jewelry.

Titanium is an important structural metal, titanium alloy because of its high strength, good corrosion resistance, heat resistance, and other characteristics are widely used in the production of aircraft engine compressor parts, as well as rockets, missiles, and aircraft structural parts, cobalt-chromium alloy is a high-temperature alloy with cobalt and chromium as the main components, its corrosion resistance and mechanical properties are very good, with its production of parts and components of high strength, high temperature, using 3D printing technology to make titanium alloy and cobalt-chromium alloy.

Titanium alloy and cobalt chromium alloy parts manufactured using 3D printing technology, very high strength and precise size, can produce the smallest size of up to 1mm, and the mechanical properties of its parts are better than the forging process.

Stainless steel is widely used for its resistance to air, steam, water, and other weak corrosive media and acid, alkali, salt, and other chemical corrosive media corrosion. Stainless steel powder! Metal 3D printing is often used in a class of cost-effective metal powder materials. A 3D-printed stainless steel model has a high strength and is suitable for printing larger-size items.

5.Ceramic Materials

Ceramic materials have high strength, hardness, high-temperature resistance, low density, good chemical stability, corrosion resistance, and other excellent characteristics in the aerospace, automotive, biological, and other industries. They have a wide range of applications, but ceramic materials’ hard and brittle characteristics make them particularly difficult to process and form, especially complex ceramic parts that need to be formed through molds. Mold processing costs are high, the development cycle is long, and it is difficult to meet the demand for continuous product updating.

Ceramic powder for 3D printing is a mixture of ceramic and binder powder. Due to the binder powder’s low melting point, laser sintering only melts the binder powder and binds the ceramic powder together. After laser sintering, the ceramic products must be put into a temperature-controlled furnace for post-processing at higher temperatures.

The ratio of the ceramic powder to the binder powder affects the performance of the ceramic parts. The more the binder portion, the easier the sintering, but in the post-processing process of the parts shrinkage is relatively large, will affect the dimensional accuracy of the parts; the binder portion is less, it is not easy to sinter and mold, the surface morphology of the particles and the original size of the ceramic material is significant to the sintering properties of ceramic materials, ceramic particles, the smaller, the closer the surface to the spherical shape. The smaller the ceramic particles and the nearer the surface is to a spherical shape, the better the sintering quality of the ceramic layer.

Ceramic powder in the laser direct rapid sintering of the liquid phase surface tension is large. The rapid solidification process will produce a large thermal stress, resulting in the formation of more micro-cracks. At present, the ceramic direct rapid prototyping process is not yet mature. Domestic and foreign, it is in the research stage and has not been commercialized.

6.Other 3D printing materials

In addition to the 3D printing materials described above, other materials currently in use include colored gypsum, artificial bone powder, cellular biomaterials, and sugar.

Colored gypsum is a full-color 3D printing material based on stone bone. It is fragile, strong, and clear in color. Based on the molding principle of printing layer by layer on the powder medium, the finished 3D printed product may have a fine granular effect on the surface after processing, which looks like a rock, and a fine annual texture may appear on the curved surface, so it is mostly used in the field of animation dolls and so on.

Combining 3D printing technology with medicine and tissue engineering could create medicines and artificial organs to treat diseases. Canada is currently developing a “bone printer” that uses similar inkjet printer technology, artificial bone powder into precise bone tissue; the printer will be made of bone powder on the film sprayed with a kind of acidic agent to make the film more rigid.

The University of Pennsylvania printout of fresh meat is the first to use the laboratory cultured cell medium, generated similar to fresh meat instead of material, water-based sol as a binder, together with special sugar molecules made. It is still in the conceptual stage of using human cells made of bio-ink, as well as the same special bio-paper. For printing, bio-ink is sprayed onto the bio-paper under the control of a computer, resulting in the formation of various organs.

Regarding food materials, the CandyFab 4000, a sugar 3D printer, can spray heated sugar to create beautiful and tasty desserts in various shapes.