3D printing is a form of additive manufacturing technology, in which three-dimensional objects are created by building upon a series of physical layers. Compared to other additive manufacturing technologies, 3D printers offer advantages such as speed, affordability, and ease of use. A 3D printer is a device that can "print" real 3D objects. Functionally, it works similarly to laser forming, employing layer-by-layer processing and additive manufacturing—that is, creating 3D entities by adding material layer by layer—which is completely different from traditional material removal processing techniques. The term "printer" is used to describe its technological principle, as the layer-by-layer processing is very similar to inkjet printing.
In recent years, the price of 3D printers has become affordable for small and medium-sized enterprises, enabling the prototyping process in heavy industry to be completed in office environments, and allowing for the use of different types of raw materials for printing.
Because rapid prototyping technology dominates the market, 3D printers have enormous potential in production applications. 3D printing technology can be widely used in jewelry, footwear, industrial design, architecture, automotive, aerospace, dental, and medical fields.
Each layer of the printing process consists of two steps. First, a layer of special adhesive is sprayed onto the area to be formed. The adhesive droplets are very small and do not spread easily. Then, a layer of uniform powder is sprayed. The powder quickly solidifies and bonds when it comes into contact with the adhesive, while the areas without adhesive remain loose. By alternating between layers of adhesive and powder, the solid model will be "printed" into shape. After printing, the loose powder can be swept away to "shave" out the model, and the remaining powder can be recycled.
Printing consumables have shifted from traditional ink and paper to glue and powder. Of course, both glue and powder are specially treated materials, which not only have requirements on the curing reaction speed but also directly affect the model's strength and the "printing" resolution. Current 3D printing technology can achieve a resolution of 600 dpi, with each layer only 0.01 mm thick, allowing for clear printing even on surfaces with text or images. However, due to the limitations of inkjet printing principles, the printing speed is inevitably not very fast. More advanced products can achieve a vertical speed of 25 mm per hour, a 10-fold improvement over earlier products, and can utilize colored glue to achieve color printing with a color depth of up to 24 bits.
Due to its high printing precision, the quality of the printed models is naturally excellent. Besides accurately depicting external curves, it also reproduces structures and moving parts with ease. When used to print mechanical assembly drawings, gears, bearings, and tie rods move normally, while the positions of cavities and grooves are precise, even meeting assembly requirements. The printed objects can be further processed through grinding, drilling, and electroplating. Furthermore, the powder material is not limited to sand casting; other materials such as elastic stretchable materials, high-performance composites, and investment casting materials are also available.
However, although 3D printer prices are constantly decreasing, and many manufacturers, design institutes, and universities are starting or preparing to equip themselves with them, the prices remain relatively high. 3D Systems' new InVisionLD entry-level desktop model is priced at $15,900, while Z Corporation's mid-range Z510 costs $100,000. Fortunately, the cost of consumables for 3D printers is not exorbitant; for example, printing a mobile phone model costs approximately $20 in materials, which is much lower than the cost of other molding technologies.
