Solid ground curing (SGC) is a photo-polymer-based additive manufacturing (or 3D printing) [1] technology used for producing models, prototypes, patterns, and production parts, in which the production of the layer geometry is carried out by means of a high-powered UV lamp through a mask. As the basis of solid ground curing is the exposure of each layer of the model by means of a lamp through a mask, the processing time for the generation of a layer is independent of the complexity of the layer. [2] SGC was developed and commercialized by Cubital Ltd. of Israel in 1986 [3] in the alternative name of Solider System.
While the method offered good accuracy and a very high fabrication rate, it suffered from high acquisition and operating costs due to system complexity. This led to poor market acceptance and systems are no longer being sold. [4] Objet Geometries of Israel retained intellectual property of the process after the closure of Cubital Ltd. in 2002, [5]
The SGC process involved hardening photopolymers by exposing the entire surface to UV light using masks. Each layer of the prototype was simultaneously cured by the UV lamp, eliminating the need for post-curing processes. The key steps in SGC include calculating the cross-section of each layer, generating an optical mask, applying a thin layer of liquid photopolymer, and exposing it to UV light. Residual liquid is removed, voids are filled with melted wax, and the layer is trimmed to the desired thickness. This process is repeated until the final layer is processed, after which the wax is melted away to reveal the completed part.
The primary advantage of SGC is that it does not require support structures, as wax is used to fill voids, resulting in highly accurate products. Models produced by SGC are particularly accurate in the Z-direction due to the milling step after each light exposure. However, the technology generates significant waste and has high operating costs, which have contributed to its decline in use.
Solid ground curing utilizes the general process of hardening of photopolymers by a complete lighting and hardening of the entire surface, using specially prepared masks. [6] In SGC process, each layer of the prototype is cured by exposing to an ultra violet (UV) lamp instead of by laser scanning. So that, every portion in a layer are simultaneously cured and do not require any post-curing processes. The process contains the following steps. [7]
The primary advantage of the solid ground curing system is that it does not require a support structure since wax is used to fill the voids, highly accurate products can be obtained. [8] The model produced by SGC process is comparatively accurate in the Z-direction because the layer is milled after each light-exposure process. [9] Although it offers good accuracy coupled with high throughput, it produces too much waste and its operating costs are comparatively high due to system complexity. [10]
Flexography is a form of printing process which utilizes a flexible relief plate. It is essentially a modern version of letterpress, evolved with high speed rotary functionality, which can be used for printing on almost any type of substrate, including plastic, metallic films, cellophane, and paper. It is widely used for printing on the non-porous substrates required for various types of food packaging.
Laser cutting is a technology that uses a laser to vaporize materials, resulting in a cut edge. While typically used for industrial manufacturing applications, it is now used by schools, small businesses, architecture, and hobbyists. Laser cutting works by directing the output of a high-power laser most commonly through optics. The laser optics and CNC are used to direct the laser beam to the material. A commercial laser for cutting materials uses a motion control system to follow a CNC or G-code of the pattern to be cut onto the material. The focused laser beam is directed at the material, which then either melts, burns, vaporizes away, or is blown away by a jet of gas, leaving an edge with a high-quality surface finish.
Since the mid-20th century, electron-beam technology has provided the basis for a variety of novel and specialized applications in semiconductor manufacturing, microelectromechanical systems, nanoelectromechanical systems, and microscopy.
Stereolithography is a form of 3D printing technology used for creating models, prototypes, patterns, and production parts in a layer by layer fashion using photochemical processes by which light causes chemical monomers and oligomers to cross-link together to form polymers. Those polymers then make up the body of a three-dimensional solid. Research in the area had been conducted during the 1970s, but the term was coined by Chuck Hull in 1984 when he applied for a patent on the process, which was granted in 1986. Stereolithography can be used to create prototypes for products in development, medical models, and computer hardware, as well as in many other applications. While stereolithography is fast and can produce almost any design, it can be expensive.
3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer control, with the material being added together, typically layer by layer.
Spin casting, also known as centrifugal rubber mold casting (CRMC), is a method of utilizing inertia to produce castings from a rubber mold. Typically, a disc-shaped mold is spun along its central axis at a set speed. The casting material, usually molten metal or liquid thermoset plastic, is then poured in through an opening at the top-center of the mold. The filled mold then continues to spin as the metal solidifies.
Powder coating is a type of coating that is applied as a free-flowing, dry powder. Unlike conventional liquid paint, which is delivered via an evaporating solvent, powder coating is typically applied electrostatically and then cured under heat or with ultraviolet light. The powder may be a thermoplastic or a thermoset polymer. It is usually used to create a thick, tough finish that is more durable than conventional paint. Powder coating is mainly used for coating of metal objects, particularly those subject to rough use. Advancements in powder coating technology like UV-curable powder coatings allow for other materials such as plastics, composites, carbon fiber, and MDF to be powder coated, as little heat or oven dwell time is required to process them.
Fusion bonded epoxy coating, also known as fusion-bond epoxy powder coating and commonly referred to as FBE coating, is an epoxy-based powder coating that is widely used to protect steel pipe used in pipeline construction from corrosion. It is also commonly used to protect reinforcing bars and on a wide variety of piping connections, valves etc. FBE coatings are thermoset polymer coatings. They come under the category of protective coatings in paints and coating nomenclature. The name fusion-bond epoxy is due to resigning cross-link and the application method, which is different from a conventional paint. In 2020 the market size was quoted at 12 billion dollars.
A photopolymer or light-activated resin is a polymer that changes its properties when exposed to light, often in the ultraviolet or visible region of the electromagnetic spectrum. These changes are often manifested structurally, for example hardening of the material occurs as a result of cross-linking when exposed to light. An example is shown below depicting a mixture of monomers, oligomers, and photoinitiators that conform into a hardened polymeric material through a process called curing.
A UV coating is a surface treatment which either is cured by ultraviolet radiation, or which protects the underlying material from such radiation's harmful effects. They have come to the fore because they are considered environmentally friendly and do not use solvents or produce volatile organic compounds (VOCs), or Hazardous Air Pollutant (HAPs), although some materials used for UV coating, such as PVDF in smart phones and tablets, are known to contain substances harmful to both humans and the environment.
Investment casting is an industrial process based on lost-wax casting, one of the oldest known metal-forming techniques. The term "lost-wax casting" can also refer to modern investment casting processes.
Rapid prototyping is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design (CAD) data. Construction of the part or assembly is usually done using 3D printing or "additive layer manufacturing" technology.
Chuck Hull is an American inventor who is the co-founder, executive vice president and chief technology officer of 3D Systems. He is one of the inventors of the SLA 3D printer, the first commercial rapid prototyping technology, and the widely used STL file format. He is named on more than 60 U.S. patents as well as other patents around the world in the fields of ion optics and rapid prototyping. He was inducted into the National Inventors Hall of Fame in 2014 and in 2017 was one of the first inductees into the TCT Hall of Fame.
Dhokra is non–ferrous metal casting using the lost-wax casting technique. This sort of metal casting has been used in India for over 4,000 years and is still used. One of the earliest known lost wax artefacts is the dancing girl of Mohenjo-daro. The product of dhokra artisans are in great demand in domestic and foreign markets because of primitive simplicity, enchanting folk motifs and forceful form. Dhokra horses, elephants, peacocks, owls, religious images, measuring bowls, and lamp caskets etc., are highly appreciated. The lost wax technique for casting of copper based alloys has also been found in China, Egypt, Malaysia, Nigeria, .Central America, and other places.
Solidscape, Inc. is a company that designs, develops and manufactures 3D printers for rapid prototyping and rapid manufacturing, able to print solid models created in CAD.
Binder jet 3D printing, known variously as "Powder bed and inkjet" and "drop-on-powder" printing, is a rapid prototyping and additive manufacturing technology for making objects described by digital data such as a CAD file. Binder jetting is one of the seven categories of additive manufacturing processes according to ASTM and ISO.
Projection micro-stereolithography (PμSL) adapts 3D printing technology for micro-fabrication. Digital micro display technology provides dynamic stereolithography masks that work as a virtual photomask. This technique allows for rapid photopolymerization of an entire layer with a flash of UV illumination at micro-scale resolution. The mask can control individual pixel light intensity, allowing control of material properties of the fabricated structure with desired spatial distribution.
Digital manufacturing is an integrated approach to manufacturing that is centered around a computer system. The transition to digital manufacturing has become more popular with the rise in the quantity and quality of computer systems in manufacturing plants. As more automated tools have become used in manufacturing plants it has become necessary to model, simulate, and analyze all of the machines, tooling, and input materials in order to optimize the manufacturing process. Overall, digital manufacturing can be seen sharing the same goals as computer-integrated manufacturing (CIM), flexible manufacturing, lean manufacturing, and design for manufacturability (DFM). The main difference is that digital manufacturing was evolved for use in the computerized world.
A variety of processes, equipment, and materials are used in the production of a three-dimensional object via additive manufacturing. 3D printing is also known as additive manufacturing, because the numerous available 3D printing process tend to be additive in nature, with a few key differences in the technologies and the materials used in this process.
3D printing speed measures the amount of manufactured material over a given time period, where the unit of time is measured in Seconds, and the unit of manufactured material is typically measured in units of either kg, mm or cm3, depending on the type of additive manufacturing technique.