3D Printing: The Printing We Know, Taken to Another Dimension

By: Jimmy Riley

Written For: All Engineering majors interested in the latest design technologies

Date: 10/23/12

This technical description paper was created to inform students in an engineering discipline about a new technology that they will likely encounter in a higher level engineering class and upon entering industry. This document could be used in an engineering class that features 3D printing, as it would educate students about the overall process.

Introduction

3D printingis making it easier and faster to producecomplex objects with multiple moving parts. This is achieved using 3D Computer Assisted Drawing (CAD) software and an additive process where many 2D layers of materials are laid down consecutively on top of one another.These processes sound fictitious, but have a look at the figure below.

Figure 1. Remote Device Prototype

At first glance the picture looks like a normal television remote, but it is actually a prototype created by a 3D printer. Three dimensional printingtechnologies minimizes the time necessary to transform an idea into a tangible object for testing and further development. Recent technological advances have allowed users to print composite models with up to seven different materials. Continue reading to learn about the process of changing a computer model into useful, physical matter.

Printing a 3D object requires more than just a 3D printer. Other essential tools include acomputer, CAD software, polymer material(s), and an educated user. The process can be summarized by the following steps:

1Using a computer, a 3D model must be created and saved as a STL file format.

2The user prepares the printer by adding powder to the powder feed box and the desired resin(s) into the resin reservoir.

3TheSTL file is sent to the 3D printer.

4Printing begins and the resin is sprayed onto the model tray by the print head, layer after layer.

5The user removes the completed model and washes away any supporting material.

6The part is now ready to use and the process can start over.

3D Printing Process: A Detailed Look

Let’s look at this process and the accompanying picture in more detail…

Figure 2. Diagram A is an external view of a 3D printer with the lid closed. Diagram B is an internal view of the working parts.

  1. CAD creation

Just like a 2D printer that can be found in many homes, a 3D printer must be told what to do in a language it understands. Therefore, the user must generate a 3D model using a CAD software program that translates an idea into an exact geometrical blueprint in the same way a 2D printer “reads directions” from a word document.

  1. File conversion

Unfortunately, a 3D printer doesn’t speak 3D modeling language, so the file must be converted to STL file format on the computer. This filetype consists of thousands and thousands of 2D layers which will later allow the printer to assemblethese layers into a final product.

  1. Printer preparation

Although the printer excels at precise fabrication of objects, it fails to completely replace human action. A user must load the resin reservoir with the desired resin, and fill the powder feed box with powder.

  1. Transmitting data and initiating printing

The user now must enable printing by sending the STL file to the printer. The printer then “reads” the file and it waits for the start command from its user.

  1. Printing

After the user presses start, the printing begins. The print head makes twopasses across the model tray to make each layer. The first pass rolls out a thin coating of powder and the second pass uses a nozzle to apply the resin, which acts as a binder. Once the resin (which is a semi-solid) comes into contact with the powder, they create a solid material. Additional powder remains around the bound material and acts as a support until printing is finished. The model tray is then lowered 28 micrometersto allow the print head to apply the next layer. This process repeats itself until the model is complete.

  1. Model removal and cleaning

The user may now remove the model after it cools down to a safe temperature. Finally the leftover supporting material is washed off.

  1. Post processing

Any post printing residue on the model tray must be scraped off by the user to ensure accurate printing for the next model.

  1. Model application

Use the printed object in its desired application.

Conclusion

While models are made in many ways, 3D printing enables the creation of highly accurate and complex modeling. In the most technologically advanced systems, multiple models can be made simultaneously with up to 7 different binding resins for each model, allowing for composite model fabrication. Industries can quickly test their ideas using this technology, which speeds up the product development process. Although 3D printing is currently exclusive to industry, families will print out household items in the near future. For a look at some examples of finished models, view the gallery on the following page.

Figure 3. Jeep CJ8 Scrambler printed at 1:25 Figure 4. Airplane Prototype

Figure 5.Multi-material guitar prototype Figure 6. Drill Prototype

Figure Citations:

Title Page, Figure 1: "Gallery." Gallery.N.p., n.d. Web. 22 Oct. 2012.

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Figure 2: "Rapid Prototyping - The 3D Printer." Rapid Prototyping - The 3D Printer.N.p., n.d.

Web. 22 Oct. 2012. <

Figure 3: "3D Printing Models at 1:25 : The Jeep CJ8 Scrambler." Shapeways.com. N.p., n.d.

Web. 22 Oct. 2012. <

Models-at-125-The-Jeep-CJ8-Scrambler.html>.

Figure 4,5, and 6: "Gallery." Gallery.N.p., n.d. Web. 22 Oct. 2012.

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Citations:

"Hair."Wikipedia. Wikimedia Foundation, 22 Oct. 2012. Web. 22 Oct. 2012. <

"How 3-D Printing Works." HowStuffWorks. N.p., n.d. Web. 22 Oct. 2012. <

EngATech. "See a 3D Printer in Action." YouTube. YouTube, 20 Aug. 2009. Web. 22 Oct. 2012. <

"Average Human Hair Diameter." - Dimensions Info. N.p., n.d. Web. 22 Oct. 2012. <