Click image to open full size
3D Printing and Additive Manufacturing
Slicing, Infill, Supports, Materials, and Tolerances
Related Tools
Related Labs
Related Worksheets
3D printing, also called additive manufacturing, is a way of making objects by building them one layer at a time from a digital design. Engineers use it to create prototypes, custom tools, medical devices, and even parts for aircraft and cars. It matters because it can reduce waste, shorten design cycles, and make shapes that are hard or impossible to produce with traditional machining. The process connects computer modeling directly to physical production, which makes it a powerful engineering tool.
In additive manufacturing, a CAD model is sliced into many thin horizontal layers, and the printer follows those instructions to deposit or solidify material in each layer. Different systems use plastics, metals, resins, or powders, and each method has tradeoffs in strength, speed, cost, and surface finish. Engineers must think about layer thickness, print orientation, support structures, and post processing because these choices affect accuracy and mechanical performance. The result is a manufacturing approach that is especially useful for rapid iteration, lightweight design, and low volume production.
Key Facts
- Additive manufacturing builds parts layer by layer from a digital 3D model.
- A sliced model divides the object into thin layers, and total build height is H = N x t where N is number of layers and t is layer thickness.
- Print time generally increases as layer thickness decreases because more layers are required for the same height.
- Material efficiency is often higher than subtractive manufacturing because less raw material is cut away as waste.
- Density = mass/volume is important for checking whether a printed part has internal voids or poor infill.
- Engineers often compare percent error using percent error = |measured - designed| / designed x 100%.
Vocabulary
- Additive manufacturing
- A manufacturing process that creates an object by adding material layer by layer from a digital design.
- CAD model
- A computer aided design file that defines the shape and dimensions of a part before it is printed.
- Slicing
- The process of converting a 3D model into many thin layers and tool paths that a printer can follow.
- Support structure
- Temporary printed material that holds up overhangs or complex features during the printing process.
- Infill
- The internal pattern and density inside a printed part that affects strength, mass, and print time.
Common Mistakes to Avoid
- Assuming 3D printing makes every part stronger, which is wrong because printed parts can be weaker between layers and their strength often depends on print orientation.
- Ignoring support material, which is wrong because overhangs and bridges may fail or deform if the design does not include enough support.
- Choosing the smallest possible layer thickness every time, which is wrong because finer layers improve detail but also increase print time and may not be necessary for the part's function.
- Treating the CAD dimensions as the final exact dimensions, which is wrong because shrinkage, warping, and printer calibration can cause the printed part to differ from the design.
Practice Questions
- 1 A part is 60 mm tall and is printed with a layer thickness of 0.20 mm. How many layers are needed to complete the part?
- 2 A printed bracket was designed to be 50.0 mm long, but the measured length after printing is 49.2 mm. What is the percent error in length?
- 3 A metal part can be made either by machining from a solid block or by additive manufacturing. Explain one engineering reason why additive manufacturing might be preferred and one reason why machining might still be better.