For many B2B buyers, Infill 3D Printing is mistakenly viewed as a simple way to save material. In reality, the internal structure of a 3D printed part is a vital, functional design parameter—a strategic tool used to control mechanical strength, weight, thermal properties, and even sealing capability. Mastering infill is essential for elevating a prototype from a visual model to a reliable, load-bearing component.
This guide goes beyond simple percentages, focusing on the sophisticated strategies used by industrial providers like Jucheng Precision Technology, especially for high-performance materials using SLS and MJF. We treat infill not as a default setting, but as an engineering decision to ensure your parts pass rigorous functional and structural tests.
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Infill is Not Just for FDM: Strategies for SLS and MJF
Infill as a Load-Bearing Design Parameter (Strength Direction)
The Hidden Role of Infill in Post-Processing and Sealing
Infill vs. Wall Thickness: Optimizing Cost and Material Use
Infill is Not Just for FDM: Strategies for SLS and MJF
While FDM (Fused Deposition Modeling) uses infill percentage to determine how much plastic thread to lay down, industrial processes like SLS (Selective Laser Sintering) and MJF (Multi Jet Fusion) operate differently, yet the concept of internal structure remains critical.
SLS/MJF: These powder-bed fusion technologies typically produce near-solid nylon parts. Infill control here is primarily about shell thickness and hollowing. Manufacturers hollow large parts to save material and time, but must engineer internal support structures to prevent collapse during the cooling process. This "hollowed structure" serves the same cost-saving function as infill.
Resin Printing (SLA/DLP): For large resin parts, hollowing is mandatory to prevent material waste and cracking due to thermal stress. The internal structure becomes a lattice (like a dense infill), providing critical support while allowing uncured resin to drain out.
The Engineering Decision: For a functional prototype, a service provider must analyze the part. If a part needs to be chemically smoothed or vapor polished, a thin shell (low infill equivalent) risks collapse. A thicker shell (higher infill equivalent) ensures dimensional stability during post-processing.
Infill as a Load-Bearing Design Parameter (Strength Direction)
The geometry of the internal structure is not random; it is chosen based on the direction of the expected load. This is a concept known as anisotropy (strength that varies by direction), which is crucial for FDM and, to a lesser extent, for other technologies when thin shells are used.
Pattern vs. Strength: A Rectilinear or Grid pattern provides uniform strength and stability, suitable for compression loads. A Honeycomb or Triangular pattern offers a better balance of rigidity and material savings, often used for parts under multi-directional stress.
Load Direction Priority: For FDM parts, if the part is loaded heavily in one direction (e.g., a simple bracket), the infill lines are oriented perpendicular to the stress for maximum resistance. A professional service analyzes the part's function to select the optimal orientation.
Aviation Aerospace Example: Components in this sector are often designed to be lightweight. Selective hollowing (the infill equivalent) is used, but the remaining outer walls are thickened in areas of high stress, effectively using the infill as a targeted support structure.
The Hidden Role of Infill in Post-Processing and Sealing
The internal structure directly impacts what can be done to the part after printing, especially for demanding applications like fluid reservoirs or outdoor enclosures.
Sealing and Porosity: Low-infill parts (especially FDM and hollowed SLS/MJF parts) are inherently porous, making them unsuitable for holding liquids or gases. For effective sealing, the outer walls must be thickened to create a dense, non-porous shell, often requiring a 100% solid fill equivalent in critical areas.
Chemical Smoothing: Processes like vapor smoothing, which are often used to achieve a final, injection-molded-like finish, can be aggressive. If the shell is too thin (due to low infill/hollowing), the chemical agent can penetrate and damage the internal structure, leading to part failure.
Vibration Dampening: Conversely, low-density infill or hollowing can be intentionally used in consumer product grips or enclosures to absorb kinetic energy, optimizing the part for shock resistance rather than maximum strength.
Infill vs. Wall Thickness: Optimizing Cost and Material Use
The most common cost mistake is over-specifying infill percentage when simply increasing the outer wall thickness would provide better strength at a lower total cost and print time.
Shell Rigidity: The outer walls contribute the vast majority of a part's stiffness and resistance to bending. For most parts, increasing the outer wall count from 2 to 3 layers has a far greater positive impact on strength than increasing infill from 20% to 40%.
Cost-Effective Strategy: A professional service will recommend a low infill (or hollowing) paired with a robust wall thickness. This strategy uses material only where it provides structural value, significantly reducing both material consumption and the long print times associated with high-density internal structures.
Transition to Molding: Understanding the optimal wall thickness from 3D printing is crucial for the eventual transition to Injection Molding, where uniform wall thickness is a fundamental DFM (Design for Manufacturing) rule.
Infill in 3D printing is a sophisticated engineering parameter, not a basic cost-saving trick. Jucheng Precision Technology’s expertise across SLS, MJF, and FDM ensures that your internal structure is optimized for mechanical performance, post-processing, and cost-effectiveness.
Elevate your prototypes from visual models to functional components. Contact us today to leverage our expertise in 3D Printing Infill and functional polymer manufacturing.
