It might seem obvious to 3D print one solid piece if all you care for is the overall strength of the final build. But it makes for a terrible idea financially as –
- You’ll require much more material per build, thus leading to much more expenditure on the spools of material you want to print.
- As you’re printing one solid block of material, it will inadvertently increase the time spent per-build, reducing the overall output from the machines.
- The entire argument about the strength of the final product goes out of the window when you realize that there are better methods to get nearly the same level of strength by using less material, as we’ll explain in the following sections.
- Printing more material also leads to some problems when slight amounts of over-extrusion can take place.
And as this is 3D printing we are talking about, we can control both the interior design (infill) as well as the exterior (walls) of the build. But is mostly the infill that contributes to the overall mechanical strength as well as the weight and other physical factors of the end product. Infills are also required when the print angle is more than 45 to support the overhanging. Thus by making the right choice about the infill, you can get an end product that is almost equally strong whilst requiring less time and material to print.
This is not to say that we are ignoring the contribution of the other factor, namely, wall thickness. But we’re going to focus on infill in this article.
Introduction to infill
Infill, in other areas related to construction, refers to filling the end-product with other materials in order to achieve physical and/or mechanical properties. In 3D printing, it refers to the density and the pattern of filament inside the build, which is either used for aesthetic purposes, or mechanical strength.
Before we move on any further, there are two important parameters, which you might have noticed about infill, pattern and density. These two factors play a huge role in terms of material used as well as the build time.
Combining the right combination of infill with specific wall thickness needed will lead to massive reduction in the cost and time required, thus leading to much more output.
Infill density or percentage
Infill density simply refers to how much of the internal volume is going to be consumed by the pattern.
Infill density can be defined in terms of the amount of filament used inside the print structure. In 3D printing density can be adjusted with the help of the slicer one can easily define the density in terms of the percentage 0% means hollow from inside and 100% means completely solid print.
The percentage simply defines the size and frequency per unit of the infill pattern, higher the percentage smaller will be the size and higher will be the infill pattern frequency. High infill density has more probability of warping and lesser density will simply not be able to support the overhanging and the print structure.
Some slicing software allows for variable density in the build, which can be beneficial for strengthening the prone areas, whilst cutting some slack on the less prone areas.
Infill pattern refers to the structure and the shape of the material inside the build, which can range from simple linear matrix to complex honeycomb-like patterns, which can have massive effects on the print time, strength as well as flexibility.
There are many types of infill pattern available on most slicing softwares, but here are the most common and useful ones –
- This pattern refers to criss-cross lines in one direction every other layer, thus providing strength along the x and y axis.
- The line pattern leads to faster builds as it consumes much less material.
- Due to its advantages it is one of the most commonly used pattern.
- Building on the lines, grid pattern refers to lines along both the x and y axis, in such a way that it makes a 90 degree angle thus strengthening the build along the dimensions mentioned.
- Grid pattern consumes average amount of material and time to build and gives a good surface finish to the printed object.
- Printed object has great strength in vertical direction when compared to diagonal direction.
- This pattern refers to the overlapping triangles with lines going along three directions in the xy plane, thus providing much more strength along the two dimensions than the above mentioned patterns.
- Triangle pattern is ideal for builds that involve much more strength along all directions whilst consuming less material and time as compared to the upcoming printing materials.
- It is a decorative infill, it has a honeycomb structure.
- This pattern is ideal to provide middle of the line-end quality in terms of strength along all the directions and the material consumption.
- It takes more time and material to print due to its complex structure.
- It is a decorative infill, having a wave like structure it is not that strong as supports don’t touch each other
- This infill pattern is used typically with flexible materials as it acts like a cushion and adds to more flexibility.
- This pattern results in the making of an infill pattern that matches the structure of the walls in the layer, just like concentric circles hence it is suited for symmetrical structures.
- Concentric pattern is ideal for quick prints with flexible parts, whilst also consuming much less material than the other patterns.
- Since the infill is simply moving along the outer surface it has more strength vertically along Y axis and due to lack of support structure in horizontal level X axis is weak.
- This pattern might be the most visually stunning, as it involves irregular curves that meet along the z-axis, just like graphene (the strongest material discovered till now), which was the inspiration for this design.
- Gyroid pattern is probably the most reliable in terms of uniformly high tensile and compressive strength along all three directions, whilst not taking too much of a toll on material and time resources.
- There are also 2D and 3D infill patterns. 2D patterns are quick to print and strong against the vertical force and not that strong when force is from any other direction. 3D patterns are strong against perpendicular force and also can tolerate force from other directions but weak in terms of vertical force.
Also time taken and material required to print each infill pattern is not the same. 10% of a pattern simply does not mean that the same amount of filament material and time will be required to print it, each printing pattern will require different time and material to print.
10% of honeycomb requires more material when compared to line patterns. This variance in time is due to the movement of the extruder, a straight line is easily printed by the extruder when compared to the complex honeycomb structure.
Depending on use of the final build, here are our generalized recommendations for printing.
Figurines or show pieces
- These pieces will not have any benefit from high structural strengths, thus you can focus on a somewhat strong build with an emphasis on time and material resources.
- Density – 0-15%
- Pattern – lines or grid
- You can ramp up the wall thickness in order to account for the low density.
- These pieces have to be of mild to moderate structural strengths whilst also maintaining the balance with weight, thus you need to strike a balance between materials and strength.
- Density – 15-50%
- Pattern – line, triangles, honeycomb
- These pieces have to be strong, thus you’ll require much more dense parts which are structurally sound, hence strength is the only thing you should focus on.
- Density – 50-100%
- Pattern – honeycomb or gyroid
- These prints are designed to be flexible, thus more than the density and pattern of the build, you should focus on the material of the build. Flexible materials such as Elastomers should suffice.
- Density – Totally dependent on the amount of flexibility you want.
- Pattern – concentric, Wiggle
It is ideal to use different infill patterns and density while printing as each portion of the print and the filament has its own specific requirement. Hence variable infill is used, these techniques can be achieved by advanced slicers which have the capabilities to slice different print portions with different infill and density settings. This practice helps saving both time and money without compromising with the print.