The strength optimization of 3D printed models focuses on adjusting the printing structure and material parameters, while precision optimization centers on controlling the error sources during the forming process. Both need to be adjusted according to specific printing technologies (such as FDM, SLA, SLS).
I. Strength Optimization: From Structure to Parameters
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Internal Structure Optimization: This is the key to improving strength, requiring a balance between strength and weight.
- Infill Rate: Directly determines the internal density of the model. Ranging from 10%-20% for lightweight infill to 50%-100% for high-strength infill, the strength increases significantly with the infill rate, but the printing time and material consumption also double.
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Infill Pattern: Different patterns have great differences in mechanical properties.
- Triangle/Honeycomb: Optimal mechanical properties with uniform stress distribution, suitable for load-bearing parts.
- Rectangle/Grid: Medium strength and fast printing speed, suitable for general structures.
- Line: Low strength, only used for non-load-bearing decorative models.
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Printing Parameter Adjustment:
- Layer Height: Smaller layer height results in tighter interlayer bonding and higher overall strength, but longer printing time.
- Wall Thickness: Increasing the outer wall thickness is one of the most direct ways to improve strength. It is recommended to set it to at least 2-3 times the nozzle diameter (e.g., for a 0.4mm nozzle, wall thickness ≥ 0.8mm).
- Printing Temperature and Speed: Ensure the material is fully melted (e.g., PLA at approximately 190-210°C) and reduce the printing speed (especially for the outer layer and infill) to reduce interlayer gaps and improve bonding strength.
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Material Selection:
- Prioritize functional materials: Such as PETG (better toughness and strength than PLA), ABS (high temperature resistance and strength but prone to warping), and nylon (wear-resistant and impact-resistant, suitable for SLS process).
- Avoid brittle materials: For example, ordinary PLA is easy to break under large external forces or low-temperature environments, making it unsuitable for load-bearing scenarios.
II. Precision Optimization: Controlling Errors and Calibration
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Equipment and Model Preprocessing:
- Model Slicing Calibration: Ensure the nozzle diameter and filament diameter set in the slicing software are consistent with the actual equipment, which is the basis for ensuring dimensional accuracy.
- Adding Support Structures: For structures such as overhangs (overhang angle > 45°) and arches, supports must be added to avoid deformation or collapse during printing, which affects precision.
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Printing Parameter Control:
- Layer Height and Initial Layer: Small layer height (e.g., 0.1-0.2mm) can improve surface precision and detail reproduction; appropriately increase the initial layer height (e.g., 0.25-0.3mm) to ensure the model adheres tightly to the printing platform and avoid misalignment.
- Flow Rate and Retraction: Calibrate the material flow rate to avoid "bulging" caused by excessive extrusion; set a reasonable retraction distance (e.g., 2-5mm) to reduce the "stringing" phenomenon when the nozzle moves, improving surface finish.
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Post-Processing Optimization:
- Support Removal and Sanding: Carefully remove supports with tools (SLA models can be cleaned with alcohol first), then sand the surface with sandpaper from coarse to fine (e.g., 400#→800#→1200#) to improve precision and hand feel.
- Chemical Polishing (for Specific Materials): ABS models can be polished with acetone vapor to dissolve small surface protrusions and achieve a mirror effect; for PLA, special polishing fluid or a heat gun (temperature must be controlled to avoid deformation) can be used.
