Stereolithography process

Generally speaking, the stereolithography process works by building the prototype, layer by layer, using a laser beam that solidifies each slice of the model until it is complete. As the model is created, multiple horizontal slices are stacked on top of each other until the model is complete. Most... 

In order to reduce the time to biuld a part via a stereolithography process, modem stereolithography machines require a more versatile liquid radiation curable resin composition. 

Methods are used to produce the more costly rapid prototypes include those that produce models within a few hours. They include photopolymerization, laser tooling, and their modifications. The laser sintering process uses powdered TP rather than chemically reactive liquid photopolymer used in stereolithography. Models are usually made from certain types of plastics. Also used in the different processes are metals (steel, hard alloys, copper-based alloys, and powdered metals). With powder metal molds, they can be used as inserts in a mold ready to produce prototype products. These systems enable having precise control over the process and constructing products with complex geometries. 

As an example stereolithography is a 3-D rapid process that produces automatically simple to very complex shaped models in plastic. Basically it is a method of building successive layers across sections of pho-topolymerized plastics on top of each other until all the thin printed layers can be joined together to form a whole product. The chemical key to the process, photopolymerization, is a well established technology in which a photo initiator absorbs UV energy to form free radicals that then initiate the polymerization of the liquid monomers. The degree... 

Rapid prototyping or stereolithography or three-dimensional object curing is a photochemical process used to produce solid three-dimensional objects, such as models, masters, or patterns with any shape directly from a design. 

Rapid prototyping (or stereolithography or 3D object curing) is a photochemical process used to produce solid 3D objects such as models, masters or patterns of any shape, directly from a design generated on a computer. The computer is used to control the illumination system that builds up the object, usually by a rapid polymerization process. An important part of the design is that the object is sectioned... 

Besides the economy-based drivers, an important factor must be considered Certain products cannot be produced by any other process but UV/EB. The cases in point optical fibers, vinyl flooring, photoresists, stereolithography and more.2... 

Stereolithography is simple in concept and it provides great economies for the design lab as well as for the modeling process. It also provides previously unrecognized challenges for the polymer photochemist, for it is entirely a laser-initiated technology, and the polymerization reactions take place to depths below a finitely thin surface layer. 

An acrylic chip was fabricated by stereolithography without an assembly process such as bonding. This fabrication method is a 3D method by solidifying a photopolymerizable resin layer-by-layer via the scanning of a UV laser beam. A special double-controlled surface method was adopted in order to produce a smooth and transparent surface for high-quality optical detection [240]. 

Although Stereolithography (SLA) is not an Inkjet 3D printing process, this method is briefly described here in order to give a better perspective on the state-of-the-art SFF technologies. 

The stereolithography (STL) process requires that you export your CAD file into an STL -file. In turn this file directs the stereolithography machine to build your prototype. If you aren t using stereolithography, you will have to convert your CAD data into another type of file format, depending on the process used. 

The thicker your stereolithography iayers are the iess accurate your prototype will be, and the less time it will take to build. Thinner layers create a smoother, more accurate model, but it takes a longer time to complete the process. 

This is when all of your initial data, prep work, and STL files merge to create your rapid prototype. The human involvement is over, and the rapid prototyping machine builds the prototype in layers—a process that can take from 10 minutes to several hours or more. Exhibit 42.1 is a stereolithography machine made by 3D Systems Corporation. 

Stereolithography builds plastic parts layer by layer by passing a laser beam (guided by a three-dimensional image) on the surface of a pool of liquid photopolymer. This photopolymer quickly solidifies where the laser beam strikes the surface of the liquid. Once one layer is completely traced, the part is lowered a small distance into the pool, allowing new liquid to cover the completed layer, and then a second layer is traced on top of the first. The layers bond and eventually form a complete, three-dimensional object after many such layers have been formed. A schematic diagram of this process is shown in Figure 6.26. 

Advantages of stereolithography are the excellent dimensional accuracy, excellent surface hnish, variable vat size and ability to use a range of materials. The disadvantages are the need for handling of liquid photopolymers and the requirement of post-processing (removal of supports) and post-curing in some cases. 

The stereolithography system is controlled by the interconnected CAD system, computer-controlled optical scanning system, control system for the platform and levelling wiper or blade for the recoating process (in between laser curing steps). 

Photofabrication or photoforming is an optical method that is similar to the stereolithography or the photomask layering process, which involves the solidification of a photochemical resin by light exposure. 

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