Manufacturing Methods and Materials: 3D Printing

Objectives and Overview

The goal of this lesson is to provide a big picture overview of 3D Printing. Many of the youth will have a basic understanding of 3D design and printing, so this lesson provides supplemental information. This lesson can be supplemented with additional relevant examples.

Lesson Objectives

  • Understand the basics of the additive manufacturing process and be able to explain how 3D printing is additive manufacturing.
  • Recognize, understand, and properly use the key terminology of 3D printing.
  • Identify the strengths and use cases for 3D printing as a manufacturing medium and be able to explain why.
  • Recognize and explain when and why to use 3D printing.

Additive vs Subtractive Manufacturing

3D Printing is a form of additive manufacturing. Additive manufacturing is when the material is added, over time, one layer at a time.

You can really see how the layers are being added on top of each other. It’s sometimes helpful to contrast additive manufacturing with another common form, subtractive manufacturing. Subtractive manufacturing is the process of starting with a large block of material and removing or cutting away chunks and pieces until it takes the form that you want. Many of the traditional forms of sculpture are examples of subtractive manufacturing.

Let’s review some examples. Wood carving is a great example of subtractive manufacturing. Here are two images demonstrating two methods of wood carving:

Two examples of wood carving: chainsaw and chunk of wood and lathe

Even though the tool is different, the process is similar. Both examples involve using a tool to create something by subtracting material from a source.

Here’s a time-lapse video that shows the difference between the two methods:

When you watch the time-lapse of the methods side by side you’re really able to pinpoint the distinctions between the processes. One core takeaway to emphasize is the difference between the amount of waste material produced by each method.

Strengths of Additive Manufacturing and 3D Printing

One of the most important things to keep in mind as you take your 3D design and printing skills to the next level is that 3D printing isn’t always the best tool for the job. It’s crucial to understand the strengths of additive manufacturing and 3D printing so that you’ll develop a sense of the best time to use this tool.

One of the strengths of additive manufacturing is that you can print hollow objects and print around something that you place inside. One example of this is a penny trap: a hollow cube with a penny inside. Here is an example of the final print with a penny inside. Laura Taalman, aka mathgrrl, has designed and printed this:

3D printed penny trap – a penny inside a 3D printed cube

This type of toy is only possible through additive manufacturing since you’re able to place an object inside while the cube is printing. Other examples are maracas since you can place the beads or rice inside the hollow object while printing.

Rapid Prototyping

One of the key strengths of 3D printing is prototyping. Since 3D printing is a relatively lower cost than other manufacturing methods, it’s a great way to prototype designs before they’re sent to mass production. 3D printing is so useful for prototyping because you essentially have an “undo” button for your physical creations. You’re able to quickly iterate and modify a design if you find something that needs to be changed after printing. This is a much faster “undo” process than in subtractive manufacturing – imagine if you had to start over while carving a wooden block! You’d likely need to get another block and start from scratch.

Making Customized Objects

Another of the main strengths of 3D printing is that you’re able to create personalized/customized objects and print them on demand. Since digital designs are relatively easy to modify once they’re created, you can create an inventory of design files that you can then modify (and sell!) when someone places a custom order. This is a much cheaper and effective way of building an inventory than having to create and store physical objects with the hope that someone will buy them.

3D Printing is Not…

While it’s definitely useful to be aware of the strengths and benefits of 3D printing and additive manufacturing, it’s also helpful to understand the limits of the medium. 3D Printing is not the new mass manufacturing as some news articles have claimed it to be in recent years. While 3D printing is an effective form of manufacturing when you’re using it with regard to its strengths, it’s certainly not a fast or cost-effective method of manufacturing lots of items. You could, however, use 3D printing to create a mold and then use that to mass manufacture objects!

3D printing is also not the best tool for every job. This is a key concept to be aware of when working with this technology. 3D printing is great when you need to create custom fits for objects, and it’s a solid choice working on projects that require this precision. 3D printing isn’t the best way to print a large box or non-customized container. You’ll begin to develop this understanding through continued practice!