What is 3D Printing?

The terms “3D printing” and “additive manufacturing” refer to processes that automatically build objects layer-by-layer from computer data. The technology is already well used in many sectors including transportation, healthcare, military, and education. Uses include buildingconcept models, functional prototypes, factory tooling (such as molds and robotarm ends), and even finished goods (such as aircraft internal components). The aerospace and medical industries in particular have developed advanced applications for 3D printing. 3D printing is sometimes referred to as “rapid prototyping,” but this term does not encompass all current uses for the technology. Materials used in 3D printing include resins, plastics, and, in some cases, metal.

Figure 1. 3D-printed models are shown with soluble support material (brown) intact, and after removal.
The earliest method, stereolithography, has been around since the late 1980s, but adoption was limited because of the toxic chemicals it required and the fragility of its models. Other technologies have evolved since then, including Fused Deposition Modeling (FDM®). FDM, introduced in the early 1990s, lays down super-thin layers of production- grade thermoplastic, yielding comparatively durable models.

Since 3D printing’s inception, system reliability and model quality have increased, resulting in diverse applications. At the same time, prices have gone down to the point where some systems are affordable even for small businesses. In a 2011 report, Wohlers Associates predicted that worldwide annual sales of additive manufacturing systems will reach 15,000 units by 2015 — more than double the 2010 rate. Lower-priced professional systems will drive most of this growth.

In FDM Technology™, printer software on the user’s Windows network or workstation accepts computer-aided design (CAD) data in major 3D file formats, including .stl, .wrl, .ply, and .sfx files. Some products also accept CT and MRI diagnostic data, protein-modeling data, and digitized 3D scans. The software works like a paper printer’s driver, sending data to the 3D printer as a job, and telling the print head where to lay down material.

Filaments of plastic modeling material and soluble support material are heated to a semi-liquid state, forced through an extrusion tip, and precisely deposited in extremely fine layers. (FDM layer thickness ranges from 0.005 inch [.127 mm] to 0.013 inch [.330 mm], depending on the system.)

The print head moves in X-Y coordinates, and the modeling base moves down the Z axis as the model and its support material are built from the bottom up. The soluble support material (shown in brown in Figure 1) holds up overhanging portions while the model is being built, and allows for complex models — even nested structures and multipart assemblies with moving parts — to be 3D printed. When the print job is complete, the support material washes away and the model is ready to be used or, if desired, finished with paint or another process.

Some 3D printers are small enough and clean enough to function as office equipment inside a department or even an individual cubicle. By comparison, large rapid prototyping systems often must be centrally located and run by a dedicated staff of experts. The very cheapest class of 3D printers comprises home-use devices now on the market for hobbyists. While fascinating for enthusiasts, these machines differ from small professional systems in that the resulting models often have poor resolution, are dimensionally inaccurate and unstable, and lack durability.

Trends toward affordability and ease of use are bringing professional 3D printing technology in-house for many designers and engineers. The growing expectation that a CAD drawing can become a real three-dimensional object in a matter of hours is altering how companies see the design process. It can be faster, more effective, and less costly.

Using 3D Printing to Accelerate Design

Time saved prototyping with in-house 3D printing vs. other methods
The longer a product stays in the design cycle, the longer it takes to get to market, meaning less potential profit for the company. With increasing pressure to get products to market quickly, companies are compelled to make quick yet accurate decisions during the conceptual stage of design. These decisions can affect the majority of total cost factors by establishing material selection, manufacturing techniques, and design longevity. 3D printing can optimize design processes for greatest potential profit by speeding iterations through product testing.

For example, Graco Inc. makes paint spraying and texturing equipment for professional use. Its engineers used a 3D printer to experiment with various paint gun and nozzle combinations to create the perfect spray pattern and volume. The resulting new spray-texture gun was based on functional prototypes 3D printed in ABS plastic. Graco estimates that 3D printing helped reduce development time by as much as 75 percent.

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