SLA (Stereolithography)

SLA is a high-precision 3D printing technology that uses liquid photopolymer resin that cures when exposed to ultraviolet light. It produces some of the finest details and smoothest surface finishes available in 3D printing.

How It Works

1. Liquid Resin: Parts are built in a vat of liquid photopolymer resin
2. UV Exposure: A laser or LCD screen exposes specific areas of resin
3. Layer Curing: Exposed resin hardens, forming one layer of the part
4. Platform Movement: Build platform moves up for the next layer
5. Support Removal: Finished parts require support removal and cleaning

Key Components

Light Source

• Laser SLA: Precise laser beam traces each layer
• LCD/DLP: Entire layer exposed simultaneously
• UV Wavelength: Specific wavelengths cure different resins

Resin System

• Resin Vat: Holds liquid photopolymer material
• FEP Film: Transparent bottom allows light transmission
• Cleaning: Regular maintenance required for optimal quality

Advantages

• High Resolution: Layer heights as low as 0.01mm
• Smooth Surfaces: Minimal post-processing for smooth finish
• Fine Details: Excellent for miniatures and detailed parts
• Overhangs: Better overhang capabilities than FDM
• Speed: Can print multiple parts simultaneously

Limitations

• Material Restrictions: Limited to photopolymer resins
• Build Volume: Generally smaller than FDM printers
• Post-Processing: Requires washing and UV curing
• Material Handling: Resins require safety precautions
• Cost: Higher material costs than FDM filaments

Material Types

Standard Resins

• Gray: General purpose, good detail
• Clear: Transparent parts after polishing
• Black: High contrast for detailed inspection
• White: Clean appearance, good for prototypes

Engineering Resins

• Tough: Impact resistant, ABS-like properties
• Flexible: Rubber-like flexibility
• High Temp: Elevated temperature resistance
• Castable: For jewelry and investment casting

Specialty Resins

• Dental: Biocompatible for dental applications
• Ceramic-filled: High temperature, ceramic properties
• Conductive: Electrically conductive properties
• Water Washable: Easier post-processing

Post-Processing Requirements

Cleaning Process

1. Remove Supports: Carefully cut away support material
2. IPA Wash: Clean in isopropyl alcohol to remove uncured resin
3. Water Rinse: Remove IPA residue
4. UV Curing: Final cure under UV light for full strength

Safety Considerations

• Ventilation: Use in well-ventilated area or fume hood
• PPE: Wear gloves and eye protection
• Skin Contact: Avoid direct contact with uncured resin
• Disposal: Proper disposal of waste resin and supports

Best Applications

Miniatures and Models

• Gaming Miniatures: High detail figurines
• Architectural Models: Precise scale models
• Prototypes: Detailed visual prototypes

Jewelry and Art

• Jewelry Patterns: Castable patterns for metal casting
• Artistic Pieces: Sculptures and decorative items
• Custom Items: Personalized detailed objects

Professional Use

• Dental Models: Surgical guides, orthodontic models
• Engineering Prototypes: Precise functional testing
• Manufacturing Tools: Jigs, fixtures, and tooling

Quality Optimization

Layer Height Selection

• 0.01-0.025mm: Maximum detail for miniatures
• 0.05mm: Good balance of quality and speed
• 0.1mm: Faster printing for larger parts

Support Strategy

• Light Supports: Minimize marks on finished parts
• Strategic Placement: Support only where necessary
• Easy Removal: Design supports for clean removal

Exposure Settings

• Bottom Layers: Longer exposure for bed adhesion
• Normal Layers: Optimized for resin type
• Over-exposure: Can cause loss of detail
• Under-exposure: Results in failed prints