The implementation principle and key technologies of 3D printing hollow models are as follows:

Design phase:

Wall thickness control: Actively design the shell thickness (usually 0.8-2mm) through CAD software (such as Fusion 360/SolidWorks), and retain the cavity inside

Topology optimization: Use generative design tools (such as nTopology) to automatically calculate the optimal material distribution and maximize the hollow area while ensuring strength

Hollow structure: Lightweight internal structures such as honeycomb and lattice can be designed instead of being completely hollow

Slicing:

Wall thickness parameters: Set "Wall Thickness" in Cura/PrusaSlicer (usually 2-4 layers of extruder width)

Filling density: Set "Infill Density" to 0% to achieve full hollowness, or 5-15% to obtain partial support

Top/bottom layer: Sufficient "Top/Bottom" must be set Layers" (usually 4-6 layers) to prevent collapse

Printing process:

FDM technology: By precisely controlling the start and stop of the extruder, stop extruding the material in the cavity area

Support structure: The suspended part needs to add soluble support (such as PVA material) or easily removable support

Multi-material printing: Some industrial-grade printers can print support structures and main bodies simultaneously

Special implementation methods:

Lost core casting: First print the hollow mold with PLA, and then dissolve the internal support material by heating

Powder sintering: SLS technology naturally forms hollow support through unsintered powder

Resin printing: LCD/DLP technology reduces the amount of resin through hollow design, and drainage holes need to be reserved

Application advantages:

Material saving is the most Up to 70% (especially for expensive materials such as metals/engineering plastics)

Weight reduction while maintaining structural strength (typical weight reduction in the aerospace field is 30-50%)

Complex internal cavity structures that cannot be achieved by traditional processes can be manufactured (such as integrated molding of hydraulic systems)

Notes:

Completely hollow structures require reserved vents (Φ1-2mm) to prevent internal air pressure from affecting printing

Thin-wall design requires consideration of material shrinkage (About 0.5-0.7% for ABS)

Functional parts require finite element analysis (FEA) to verify structural strength

Typical case: Germany's EOS metal 3D printed turbine blades, with internal cooling channels and wall thickness precisely controlled to 0.3mm, increase the operating temperature by 200℃.