In this article we’ll explain how to apply infill or filling in 3D printing, how to set the correct percentage to optimise strength-to-weight ratios. We’ll also cover most troubleshooting issues surrounding rapid prototyping with infills.
Infill or filling is one of the most important variables when 3D printing a part, this term refers to the internal structure printed inside of an object. Its density, patterns & orientation are all factors comprising how a part is made up effecting its strength and functionality. It determines how reliable & efficient it is to print flat, horizontal faces over an empty space.
This area of a 3D print is the outside wall or surface of a part that’s typically built up on the z-axis. The golden rule for defining shell thickness is to ensure that it is a multiple of the nozzle diameter, to prevent gaps / voids between the walls leading to weaker parts.
Shells can be a useful variable when defining infills, strength can be added to parts by increasing this outside wall thickness and can help to reduce the infill density. However this is a balancing act and for smaller components can lead to increased material, print times & costs.
This is a great tool to utilise for parts that are being post-processed (sanding, polishing or chemical smoothing). It is mandatory that this variable is increased to reduce the amount of surface penetration from these processes.
Bottom section of a part, typically attached to the build plate. This variable won’t effect part strength or functionality too much, however its recommended to adjust this value so that the surface is fully filled in.
Upward section of a part, typically the last section of a component to be printed. This variable is important to ensure the infill is bridged and filled in and sometimes is a higher value than the bottom layers for certain materials.
The standard go-to infill type for 3D printer, as it provides a reasonable amount of rigidity in all directions without compromising print times. Biggest advantage of this infill type is that it requires minimal bridging.
Appropriate when strength is required in the direction of the outside wall / shell. This infill type takes longer to print, however is better suited for printing taller parts such a pillars or lithopanes.
Waveform or ripple style pattern, that’s well suited for parts that need to twist or compress, This infill type is best suited for flexible materials and is slower to print than rectangular & triangular patterns.
This is the most popular infill pattern in 3D printing, as is provides the greatest strength in all directions due to its out-of-plane shear properties. The only downside to this infill type is the increased print times.
The density of an infill refers to the percentage of the inside void space of a part that will be occupied by material. Typically the higher the density = more strength. However the gains may not be as much as you think.
At SGD we use a standard infill of 20% (light). Users can upgrade their infill to four different levels; ultra light (10%), light (20%), medium (50%) or solid (100%).
For parts that are being screwed, tapped or bolted in anyway we recommend a base infill of 50% for maximum strength. Increase in shell thickness & infill density will result in better compressible strength which provides for better anchoring.