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How Does a 3D Printer Work?

Learn how 3D printers work and are able to create 3D objects through various printing methods and technologies.

There are upwards of a dozen types of 3D printing processes in use today. 3D printing began in the early 1980s to replace hand-made models and prototypes carved from wood or stuck together from pieces of card or plastic.

3D printing is a logical extension of rapid prototyping (where models and prototypes are developed by automated methods). The result is savings of both time and money. 3D printing has expanded to engineering, manufacturing, business and even personal use.

3D printing is achieved through additive manufacturing — the process by which material is joined under computer control to create a three-dimensional object. The material, ranging from liquid resin to powdered grains, is fused together layer by layer. A variety of shapes, including very complex ones, are easily printed from a digital 3D model or CAD file.

Additive manufacturing is the opposite of subtractive manufacturing, which carves away at an object. In other words, 3D printers work by building up a three-dimensional model one layer at a time, from the bottom upward. 

Printer Types

There are upwards of a dozen 3D printing methods that are used to develop 3D objects. Here are a few of the more common and popular 3D printing technologies that use either plastic resin or a material powder to create three-dimensional objects from computer files.

Fused deposition modeling (FDM) is currently the most popular and readily available form of desktop 3D printing on the market. Developed and originally implemented in the 1980s, Fused deposition modeling allows you to print operational prototypes as well as ready-to-use products as such LEGO bricks, plastic gears and much more. All components printed with FDM can go in high performance and engineering-grade thermoplastic, which makes this technology useful for mechanical engineers and manufacturers.

Printed pieces have excellent mechanical strength and heat resistance. FDM printers construct 3D objects layer by layer, starting at the bottom and moving upwards by heating and extruding thermoplastic filament. This form of 3D printing is useful in all fields from new product development to prototyping to end-product manufacturing.

Stereolithography (SLA) is the oldest form of 3D printing. It works by exposing a layer of photosensitive liquid resin to a UV-laser beam; the resin then hardens in the desired pattern, and the object is built layer by layer until it is complete. Objects printed by SLA 3D printers have smooth surfaces, but often the quality depends upon the printer type. Printing via SLA involves a longer process as printed objects need to be rinsed using a solvent and then put into an ultraviolet oven to complete processing.

Digital Light Processing (DLP) is the fastest of all 3D printing methods. A layer of hardened material can be printed in a few seconds and quickly transferred to allow for printing of the next year. Like SLA, DLP 3D printers use liquid plastic resin but instead of a UV-laser beam, the resin is melted with arc lamps. This light source causes the impressive printing speeds because the amount of light allows the resin to quickly harden. DLP is a robust technology that produces high resolution models every time, even allowing you to use cheaper materials for complex and detailed objects.

Selective Laser Sintering (SLS) technology builds objects layer by layer like other printing methods, but a major difference is that it uses powdered material rather than liquid resin. SLS uses a laser to form strong 3D printed objects from powdered material, which allows objects to be printed without any additional support structures. SLS is popular for printing customized goods because a large selection of materials may be used, such as nylon, glass, ceramic, aluminum, silver, steel and more.

Advantages and Disadvantages of 3D Printing

3D printing is more than 10 times faster and five times cheaper than other methods, allowing you to build prototypes and other objects in hours rather than days. In addition, 3D printers are often one-tenth of the price of more sophisticated rapid prototyping machines. The printers are small, safe, reliable and easy-to-use, which is why they are becoming more and more popular in areas outside of manufacturing.

There are a few cons to using 3D printers as well. Compared to high-end rapid prototyping machines, the finish of your objects will be inferior, including the texture. Material choice is often limited, as well as the colors you want to use. Lower-end devices will produce lower quality objects, so if you want better results, it will cost you a lot more money.

With so many uses for 3D printers and so many different printer types available, it is easy to see how 3D printing has grown exponentially over the past three decades.

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