FAQ About FAQ-News

I. Basic Understanding

1. What is SLA (Stereolithography Apparatus)?

SLA is a representative additive manufacturing (3D printing) technology that uses ultraviolet (UV) light to selectively cure liquid photopolymer resin layer by layer. It constructs 3D parts by solidifying the resin surface according to the cross-sectional data of the model, layer upon layer stacking from the bottom to the top. SLA is renowned for its high forming precision and smooth surface finish, making it widely used in prototype manufacturing and small-batch production.

2. What are the core differences between SLA and other 3D printing technologies (such as FDM, SLS)?

The key differences lie in materials, forming principles, and performance: ① Materials: SLA uses liquid photopolymer resin, while FDM (Fused Deposition Modeling) uses solid thermoplastic filaments, and SLS (Selective Laser Sintering) uses powdered materials (such as nylon, metal); ② Forming principle: SLA relies on UV light curing of resin, FDM on melting and extruding filaments, and SLS on laser sintering of powder; ③ Performance: SLA has the highest surface smoothness and dimensional accuracy (tolerance up to ±0.05mm), but parts are usually brittle; FDM is low-cost and easy to operate but has obvious layer lines; SLS can make parts with high toughness and no support needed, but has lower precision than SLA and higher equipment cost.

3. What types of photopolymer resins are commonly used in SLA, and their applicable scenarios?

Mainstream resin types and applications: ① Standard resin: Low cost, fast curing speed, suitable for making non-functional prototypes (such as architectural models, product appearance samples); ② Tough resin: Enhanced impact resistance and flexibility, used for functional prototypes (such as gears, hinges, structural parts); ③ High-temperature resin: Can withstand high temperatures (up to 150℃-200℃) after post-curing, suitable for mold making and high-temperature test parts; ④ Dental/medical resin: Biocompatible, compliant with medical standards, used for dental models, surgical guides; ⑤ Transparent resin: High light transmittance after polishing, suitable for light-transmitting parts (such as lenses, display covers).

II. Process Characteristics

4. What are the main process steps of SLA?

The standard process includes six steps: ① Model preparation: Design a 3D model using CAD software and export it as an STL file, then slice the model into layers (layer thickness 0.025mm-0.1mm) with slicing software; ② Resin preparation: Pour the selected photopolymer resin into the resin tank of the SLA machine, ensuring the resin temperature and viscosity meet the process requirements; ③ Layer-by-layer curing: The UV laser scans the resin surface according to the slice data, curing a single layer of the model; ④ Platform lifting: After curing one layer, the build platform rises by a distance equal to the layer thickness, and the resin covers the cured layer; ⑤ Post-curing: After the whole model is formed, take it out, clean the residual liquid resin with isopropyl alcohol (IPA), then put it into a UV curing box for secondary curing to improve mechanical properties; ⑥ Post-processing: Trim support structures, polish the surface, and perform painting or assembly if needed.

5. What are the advantages of SLA technology?

Core advantages focus on precision and surface quality: ① High precision and smooth surface: No obvious layer lines, surface roughness (Ra) can reach 0.1μm-0.8μm, avoiding a lot of post-polishing work; ② Fast forming speed for small parts: Suitable for making small and medium-sized complex prototypes, with shorter forming cycle than traditional processing; ③ Strong ability to form complex structures: Can make parts with hollow structures, undercuts, and intricate internal channels that are difficult to process by traditional methods; ④ Wide material selection: Resins with different properties (toughness, high temperature resistance, transparency) can be selected according to needs; ⑤ Low material waste: Only the resin used for forming and supports is consumed, and excess resin can be recycled.

6. What are the limitations of SLA technology, and how to address them?

Main limitations and solutions: ① Brittle parts: Most standard resins are brittle and not suitable for load-bearing parts; solve by selecting tough resin or reinforcing with fiber-filled resin; ② Resin curing shrinkage: During curing, resin shrinks, which may cause part deformation or warpage; optimize slice parameters (reduce layer thickness), extend post-curing time, and design reasonable support structures to reduce shrinkage stress; ③ Limited part size: The forming size is restricted by the resin tank volume of the SLA machine; for large parts, use split forming and then bond them with special adhesive; ④ High cost: SLA equipment and resin are more expensive than FDM; reduce costs by selecting cost-effective resins and improving production efficiency; ⑤ Environmental and safety risks: Resin is toxic and UV light is harmful; operate in a well-ventilated environment, wear protective gloves and goggles, and dispose of waste resin according to environmental regulations.

III. Applications and Quality

7. In which industries is SLA mainly applied?

Core applications cover multiple fields: ① Product design and prototyping: Automobile, consumer electronics, and home appliance industries use SLA to make appearance prototypes and functional test parts, accelerating product development cycles; ② Mold making: Make rapid prototypes for vacuum casting molds, reducing mold development time and cost; ③ Medical and dental: Dental models, surgical guides, orthopedic braces, relying on high precision and biocompatible resins; ④ Aerospace: Small complex parts, such as engine components and cabin models, for performance testing; ⑤ Cultural and creative industries: Artworks, sculptures, jewelry prototypes, realizing personalized customization; ⑥ Education and research: Used for teaching demonstrations and scientific research experiments to show 3D structure principles.

8. What are the common defects of SLA parts and their causes?

Typical defects and causes: ① Layer separation: Insufficient curing of resin, low laser power, or excessive layer thickness, leading to poor bonding between layers; ② Deformation/warpage: Resin curing shrinkage, unreasonable support structure, or uneven cooling during post-curing; ③ Surface blemishes: Residual liquid resin not cleaned thoroughly, dust in the resin, or scratches during post-processing; ④ Incomplete curing: Low UV laser energy, too fast scanning speed, or expired resin with reduced photosensitivity; ⑤ Support failure: Insufficient support density or unreasonable support position, causing the part to collapse during forming.

9. How to inspect and improve the quality of SLA parts?

Quality inspection and improvement methods: ① Dimensional inspection: Use a caliper, coordinate measuring machine (CMM) to detect dimensional accuracy, ensuring compliance with design requirements; ② Surface inspection: Visual inspection and roughness meter to test surface smoothness, removing blemishes by polishing; ③ Mechanical performance testing: Sampling test tensile strength, impact strength, and hardness after post-curing, adjusting resin type and post-curing parameters if needed; ④ Improvement measures: Optimize slice parameters (layer thickness, laser power), enhance support structure design, ensure thorough cleaning and sufficient post-curing, and use fresh resin and regular equipment maintenance.

IV. Production and Environmental Protection

10. What are the requirements for SLA equipment and operating environment?

Equipment and environment requirements: ① Equipment: The UV laser (wavelength 355nm is common) must have stable power output; the resin tank should be made of quartz glass with high light transmittance; the build platform needs high flatness and stable lifting accuracy; ② Environment: Temperature control at 20℃-25℃ (resin viscosity is sensitive to temperature), humidity 40%-60% RH; avoid direct sunlight and dust to prevent resin deterioration and surface defects; good ventilation to discharge volatile organic compounds (VOCs) from resin; ③ Safety equipment: Equip with UV protective barriers, IPA cleaning tanks, and waste resin treatment tools.

11. How to handle SLA waste resin and used parts environmentally?

Environmental protection disposal methods: ① Waste resin: Collect unused liquid resin in sealed containers, avoid mixing with water or other substances; send to professional hazardous waste treatment institutions for disposal, do not pour into sewers; ② Cleaning waste liquid: IPA used for cleaning parts contains residual resin, which needs to be sealed and stored, then distilled and recycled, or handed over to professional institutions; ③ Used parts: Non-biomedical parts can be crushed and disposed of as general solid waste; biomedical parts must be disinfected first, then disposed of in accordance with medical waste regulations; ④ Energy saving: Turn off UV light and equipment power when not in use, and recycle excess resin in the resin tank.

12. What are the key points of SLA equipment maintenance?

Core maintenance points: ① Laser system: Regularly check laser power and lens cleanliness, clean lenses with professional cleaning agents to avoid light attenuation; ② Resin tank: Clean residual resin after use, check for quartz glass scratches (replace if damaged), and avoid hard objects touching the tank bottom; ③ Build platform: Clean and calibrate flatness regularly, remove cured resin residues; ④ Motion system: Lubricate the guide rail and screw of the lifting platform to ensure stable operation; ⑤ Software and parameters: Update slicing software in time, record and optimize process parameters, and back up data regularly.

V. Selection and Cost

13. Which products are suitable for SLA instead of other 3D printing technologies?

Scenarios preferred for SLA: ① Small and medium-sized parts requiring high surface smoothness and dimensional accuracy (such as product appearance prototypes, dental models); ② Complex structure parts with hollow, undercut, or internal channels (difficult for FDM and traditional processing); ③ Functional test parts requiring specific resin properties (high temperature resistance, transparency); ④ Small-batch customized parts (such as jewelry, cultural and creative works). For large parts, low-cost prototypes, or metal parts, FDM, SLS, or other technologies are more suitable.

14. What constitutes the cost of SLA production, and how to control costs?

Cost composition and control methods: ① Equipment cost (30%-40%): Initial investment in SLA machines is high; choose equipment with appropriate forming size according to needs, avoid overcapacity; ② Resin cost (25%-35%): Resin price varies by type; select cost-effective resin for non-high-performance parts, and recycle excess resin; ③ Auxiliary cost (15%-20%): IPA, UV curing energy, support materials; optimize cleaning process to reduce IPA consumption, and shorten unnecessary post-curing time; ④ Labor and maintenance cost (10%-15%): Improve operation proficiency to reduce forming failures, and do regular maintenance to extend equipment service life; ⑤ Post-processing cost: Optimize model design to reduce support structures, minimizing trimming and polishing work.