Eliminate Material Waste: Understanding 3D Printing Infill Patterns to Create Stronger, Lighter Parts
Unlike many traditional manufacturing techniques, 3D printing allows for precise control over the two most important elements of a part: the outer walls and the infill. If infill density and pattern settings are not optimized, it leads to material waste, part failure, and longer print times.
Regardless of thickness, the walls constitute the outermost layer of a part, while the infill is the material that fills the interior. While the scope for adjusting walls is limited, infill is more flexible and plays a critical role in various properties, such as the part's strength, weight, structure, and buoyancy.
In 3D printing, these properties are controlled via parameters in your slicing software. Two particularly important settings are infill density (0% to 100%) and infill pattern (usually selectable from multiple shapes).
Let’s explore what options are available and how you can utilize them for your 3D printed parts.
What is Infill Density?
Infill density is a value indicating how "filled" the interior of a part is. It is defined in slicing software as a percentage from 0% to 100%, where 0% means hollow and 100% means completely solid. As you might imagine, it significantly affects the weight of the part, but being solid doesn't always guarantee the highest strength.
Density also affects print time, material consumption, and even buoyancy. Some slicing software allows for "variable infill density," which lets you set different densities within a single part. This allows you to increase infill and reinforce only the necessary areas without adding weight to the entire model.
What Percentage Should I Set for Infill Density?
You should choose the infill density based on the requirements of your part, but density alone does not determine strength. Material, print orientation, wall thickness, infill pattern, and the direction and type of load are equally important.
Setting infill density to 100% maximizes the amount of internal material, but it significantly increases print time and material consumption, and is rarely necessary. Instead of making the entire part completely solid, it is generally more efficient to add more walls or use local infill modifiers to reinforce areas subject to high loads.
Display models such as figurines can usually be printed with a relatively low infill density of 5%–15%. Depending on the geometry, it may even be possible to print completely hollow (0% infill), but internal support may be needed to ensure top surfaces or gentle slopes print cleanly.
Lithophanes are a special case. Because they need to transmit light uniformly through the image area, they are usually printed at near-solid or fully solid settings. Depending on the model, you can achieve the same effect by configuring a sufficient density of walls.
For screw threads or fastening components, you may need to add material around holes or bosses, but it is not necessarily required to set the entire model to 100% infill density.
For flexible materials like TPU, infill density is a crucial means of adjusting the feel of the finished product. Generally, lower density makes the part easier to deform, while higher density makes the part stiffer and more resistant to compression. Since wall thickness, infill pattern, and the hardness of the TPU itself also have a significant impact, there is no single infill density that is appropriate for all flexible prints.
Slicing Software Presets and Bambu Studio Infill Settings
Many modern slicing software packages come with density presets optimized for various printing needs. By using these, you can quickly select appropriate print parameters without having to adjust every setting manually.
For example, in Bambu Studio, you set the infill percentage in the "Sparse Infill Density" field. There are also printing modes that combine recommended infill patterns, which is useful when you want to prioritize slicing speed. These modes indirectly affect infill density and the strength of the printed object by changing various settings.
Which Infill Pattern Should I Choose for 3D Printing?
To help you choose the best pattern for your part requirements, we have summarized common options below, categorized by relative strength, the planes/directions where strength is achieved, material efficiency, print speed, and primary applications.
Infill Patterns for Figurines and Display Items
| Pattern | Strength | Material Usage | Print Speed | Applications |
|---|---|---|---|---|
| Line | Very low (X or Y axis direction) | Low | Fast | Prototypes, geometry verification prints |
| Grid | Low to Medium | Low to Medium | Medium | From prototypes to functional models depending on density |
| Lightning | Low (strength only where needed) | Low | Fast | Prototypes, decorative models, shell-only designs |
| Voronoi | High (organic and irregular) | Low | Slow | Protective cages, lampshades |
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Line
Line infill prints lines in one direction (X or Y axis) while alternating the direction for each layer. It provides strength only in two-dimensional directions and is suitable for quick printing, but it ranks among the weakest of all patterns. It is characterized by low material usage and being lightweight. It is best suited for initial prototyping and geometry verification prints, such as simple smartphone stands or rough models.
Grid
Grid infill is commonly used as a default setting. While it looks similar to the line pattern, it differs by placing a two-dimensional grid of lines in each layer rather than lines in one direction. Both material usage and print time are medium, and it is often used for wall-mounted brackets and support components for cameras or other housings.
Lightning Pattern
This pattern is designed to focus material only where structurally necessary, such as under the top layer or overhangs, to support the interior. The result is a tree-like structure resembling lightning. Because it significantly reduces print time and material usage, it is suitable for prototypes, decorative models, and shell designs that do not require much internal strength.
Voronoi
Voronoi is a geometric structure that divides space into regions based on the proximity of points to a specific set of seed points. It creates organic shapes resembling natural structures like honeycombs or skeletons. Unlike other patterns, it is not usually applied directly in slicing software; instead, the model's geometry must be modified in advance using different software.
Infill Patterns for General Prints
| Pattern | Strength | Material Usage | Print Speed | Applications |
|---|---|---|---|---|
| Honeycomb | High (2D) | Medium | Moderately fast | Drone frames, structural panels |
| Grid | Medium (2D) | Medium | Medium | Wall brackets, housings |
| Triangular | Medium to High (2D) | Medium | Medium | Flat covers for housings |
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Honeycomb
Because honeycomb structures distribute force evenly, they are suitable for prints that need to ensure medium strength without adding too much weight. For example, they can be used for drone frames, skateboard parts requiring durability, and structural panels.
Triangular
The triangular pattern consists of lines in three directions on the XY plane. It is suitable for parts requiring high rigidity within a plane, such as flat covers for housings.
Infill Patterns for Functional Parts
| Pattern | Strength | Material Usage | Print Speed | Applications |
|---|---|---|---|---|
| Tri-Hexagon | High (2D) | Medium | Medium | Speaker grilles, decorative covers |
| Cubic | High (3D) | Medium to High | Medium to Slow | Drone arms, structural connectors |
| Cubic Subdivision | High (3D strength where needed) | Medium | Medium | Large parts, thick-walled housings, toolbox lids |
| Quarter Cubic | High (3D) | Medium | Slow | Thin parts, robot housings, spacers between parts |
| Gyroid | High (Isotropic) | Medium | Medium | Prosthetics, wind tunnel structures |
| Octet | High (3D) | High | Slow | Motor brackets, jigs and fixtures |
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Tri-Hexagon
Tri-hexagonal infill is composed of lines in three directions on the XY plane, with triangles placed between hexagons. It ensures two-dimensional strength while creating a visually distinctive shape, making it suitable for speaker grilles and decorative electronic housings.
Cubic
The cubic pattern has excellent strength in three-dimensional directions but requires more material and time than other patterns. It is suitable for mechanical parts subjected to stress from multiple directions, such as drone arms, structural joints, and connectors.
Cubic Subdivision / Adaptive Cubic
Essentially a smarter version of the cubic pattern, it maintains strength while reducing material usage and increasing print speed. It consists of cubes of different sizes, with larger cubes placed in the center of the part. In slicing software like Bambu Studio or PrusaSlicer, this pattern is called "Adaptive Cubic."
Quarter Cubic
Composed of tetrahedrons and truncated tetrahedrons, it forms high-strength infill layers that effectively distribute large loads. It is suitable for thin functional parts that require high strength, such as robot housings or spacers between parts.
Gyroid
The spiral-like gyroid infill pattern connects walls in three-dimensional space, ensuring relatively well-balanced strength overall. Composed of continuous complex curved surfaces, it is often used for applications where a balance of strength, material usage, and print time is important, such as prosthetics, bicycle handlebars, and wind tunnel structures.
Octet
The octet infill is a three-dimensional pattern that is not only visually beautiful but also suitable for high-strength parts. For example, it can be used for motor brackets, 3D printer parts, and workshop jigs and fixtures.
Infill Patterns for Flexible Prints
| Pattern | Strength | Material Usage | Print Speed | Applications |
|---|---|---|---|---|
| Concentric | Low (Rigid only in Z-axis) | Low | Fast | Transparent parts, TPU gaskets, dampers, wearable wristbands |
| Cross | High (2D) | Medium | Medium | Ergonomic grips, flexible smartphone cases, compressible buttons |
| Cross 3D | High (Flexible in 3D directions) | Medium | Medium | Art lighting, decorative vases, flexible printed parts |
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Concentric Infill
Concentric infill is composed of concentric lines that follow the contour of the part. It features fast print speeds and lower material consumption than many other patterns. It is commonly used for TPU gaskets, dampers, and wearable watch bands.
Cross
Cross is suitable for flexible materials, forming a cross-shaped structure inside the part. Since there are no long straight lines, it is easy to bend or twist, and it is often used for ergonomic grips, flexible smartphone cases, and compressible buttons.
Cross 3D
Cross 3D is softer in all directions and has excellent elasticity, but it has the disadvantage of taking longer to slice. It is also suitable for flexible filaments because it does not require frequent retractions.
Common 3D Printing Infill Issues and Solutions
While infill patterns and density help improve strength, improper settings can cause problems. Here are common symptoms and how to deal with them.
If the infill density is too low, the internal structure may not sufficiently support the top layer, leading to surface irregularities, sagging, or pillowing. This can be addressed by increasing the infill density or inserting solid layers at regular intervals.
If infill lines become thin, weak, broken, or incomplete, it is often caused by under-extrusion. Reduce the infill print speed or increase the extrusion width, and check that there are no clogs in the PTFE tube.
If the infill does not bond well to the walls, the strength of the interior of the part is reduced. This can be addressed by increasing the overlap between the walls and the infill. For example, in Bambu Studio, you can adjust the default 15% to about 20%, though setting it too high may lead to surface defects.
Using patterns with fast print speeds but low strength, such as Line or Lightning, for structural parts that bear loads can lead to structural failure. Consider using 3D infills like Cubic or Gyroid for parts requiring high strength.
If infill does not align layer by layer or appears shifted, it may be caused by loose belts, pulley defects, or print speed and acceleration settings being too high. Check the tension of your belts and consider reducing speed and acceleration.
Variable Infill Settings: Reinforcing Only Where Truly Needed
Infill density does not need to be uniform throughout the model. Many slicing software packages allow you to change the infill density or number of walls in selected areas. This allows you to add material only where necessary without increasing the density of the entire printed object.
Bambu Studio
Bambu Studio has two practical ways to achieve this. The "Height Range Modifier" allows you to override settings such as sparse infill density within a specified height range of the model. For example, you can set the bottom half of the print to 10% infill density and increase it to 50% above a specified height.
For more precise local reinforcement, you can also add 3D shapes for use as modifiers to the model. By placing a cube or other shape at mounting points, screw bosses, or other selected areas, you can change the sparse infill density or number of walls only in the part where the modifier overlaps with the model.
Bambu Studio also features Adaptive Cubic infill. It automatically adjusts the size of the cubic structure, using higher density near the model's surface and lower density in the interior. Support Cubic infill is based on a similar principle, but its primary purpose is to increase density as you approach the interior ceiling to provide support.
PrusaSlicer
PrusaSlicer also allows you to change settings for specific Z-ranges with the height range modifier. It also supports local changes using modifier meshes, allowing you to increase infill or add perimeters only around high-load areas.
PrusaSlicer’s Adaptive Cubic infill uses fine cells near the model surface and larger cells in the center. This reduces material usage while still supporting the top layers.
Cura
Cura also allows you to apply different settings to selected areas using modifier meshes. By combining support blockers with "Per-model settings," you can locally change the infill density in areas that overlap with the model.
Cura also has a feature that gradually decreases infill density as the distance from the top surface increases. This maintains high support density just below the top layer while saving material and print time.
Infill Layer Height and Angle
In some slicing software, you can set the infill layer height independently from the model's wall thickness. Increasing the infill layer height allows you to combine multiple infill layers into a single printing operation, reducing the number of passes and saving time. If you set it to the same height as the standard layer height, the infill will be printed on every layer.
The impact of infill on mechanical properties depends on the material, pattern, geometry, and loading. Therefore, changing this setting is not a universal solution for increasing strength.
Infill orientation also affects mechanical properties. For example, an alternating orientation setting like +45° and -45° is commonly used to achieve relatively balanced performance within the XY plane.
On the other hand, if the primary loading direction is known, aligning the extrusion path closer to that direction can potentially increase strength in that axis. Therefore, when designing functional parts, you must consider not only the infill angle but also the orientation of the part and the placement of the perimeters.
Infill Art: Using Infill Beyond Just Hiding It Inside the Model
Infill patterns can be used not only to stay hidden inside a model but also as part of the printed object's aesthetics. By using geometric structures such as Gyroid, triangles, or honeycomb, you can create decorative lattice patterns suitable for jewelry, accessories, lighting, and exhibits.
Setting the number of top or bottom solid layers to zero allows you to expose the infill on those surfaces. Additionally, reducing the wall thickness or the number of perimeters can make the infill visible on the sides.
Depending on the design, using a small-diameter nozzle can reproduce finer lattice details. However, there is no single ideal nozzle diameter or material color for infill art. You can create various visual effects by adjusting the pattern, density, orientation, material color, translucency, and surrounding shell.