If you work with 3D printed light-cured parts—whether for prototypes, medical models, or jewelry—understanding surface roughness is critical to meeting quality and functional needs. Light-cured 3D printing (like SLA and DLP) is known for high detail, but its surface roughness can vary widely from Real academia de bellas artes 0.5 μm a RA 5 μm depending on key factors. This guide breaks down typical roughness ranges, core influencing factors, practical application standards, and actionable tips to improve surface quality.
1. Typical Roughness Ranges for 3D Printed Light-Cured Surfaces
Light-cured 3D printing (SLA and DLP) produces smoother surfaces than many other technologies (P.EJ., MDF), but the exact roughness depends on technology type, parámetros, y materiales. Below is a detailed breakdown of standard ranges:
| Tipo de tecnología | Typical Roughness (Real academia de bellas artes) | Optimal Roughness (With Optimization) | Key Advantages for Surface Quality |
| SLA (Stereolithic) | 1 μm ~ 3 μm | < 1 μm | High laser precision, líneas de capa mínima |
| DLP (Procesamiento de luz digital) | 1 μm ~ 5 μm | ~ 1 μm (High-Resolution DLP) | Impresión rápida; 4K projectors narrow roughness gaps with SLA |
| General-Purpose Resin (Any Tech) | 2 μm ~ 5 μm | 1 μm ~ 2 μm (With Post-Processing) | Rentable; suitable for non-critical prototypes |
| High-Precision Resin (P.EJ., Dental) | < 1 μm | 0.5 μm ~ 1 μm (With Fine Tuning) | Baja contracción; ideal for medical or jewelry parts |
Nota: Real academia de bellas artes (Average Surface Roughness) is the most common metric—lower values mean smoother surfaces. Como referencia, a polished metal surface has an Ra of ~0.02 μm, while a standard light-cured part (sin postprocesamiento) falls between 1 μm ~ 3 μm.
2. 4 Core Factors That Impact Light-Cured Surface Roughness
Surface roughness isn’t random—it’s shaped by controllable factors. Understanding these lets you adjust parameters to achieve your desired smoothness. Below is a breakdown with specific examples and data:
(1) Tecnología de impresión & Equipment Precision
The type of light-curing technology and device resolution directly affect surface quality:
- SLA: Uses a focused UV laser to cure resin layer by layer. Industrial-grade SLA machines (P.EJ., Stratasys) have laser spot sizes as small as 0.02 milímetros, producing surfaces with Ra < 1 μm. Consumer-grade SLA machines may have larger spots (0.05 mm ~ 0.1 milímetros), leading to Ra 2 μm ~ 3 μm.
- DLP: Uses a projector to cure entire layers at once. Resolution matters here—4K DLP projectors (with smaller pixel sizes) can reach Ra ~ 1 μm, while 1080p projectors may result in Ra 3 μm ~ 5 μm due to visible pixel edges.
(2) Parámetros de impresión
Even with the right equipment, poor parameter settings can ruin surface smoothness. The two most critical parameters are:
Espesor de la capa
Thinner layers mean fewer visible layer lines, but overly thin layers can cause resin flow issues. Here’s how layer thickness impacts roughness:
| Espesor de la capa | Typical Roughness (Real academia de bellas artes) | Notas |
| 0.025 milímetros | 0.5 μm ~ 1 μm | Ideal for high-detail parts (P.EJ., joyas) |
| 0.05 milímetros | 1 μm ~ 2 μm | Balances smoothness and print speed |
| 0.1 milímetros | 2 μm ~ 3 μm | Impresión rápida; líneas de capa visibles |
| > 0.1 milímetros | 3 μm ~ 5 μm | Only for rough prototypes |
Tiempo de exposición
- Insufficient exposure: Resin doesn’t cure fully, leaving sticky, superficies desiguales (Ra can jump to 4 μm ~ 6 μm).
- Overexposure: Resin shrinks excessively, causing warping or surface cracks (Ra increases by 1 μm ~ 2 μm).
Mejor práctica: Follow the resin manufacturer’s recommended exposure time (P.EJ., 5 seconds per layer for standard resin).
(3) Resin Material Properties
Not all resins are equal—formulation affects shrinkage and surface finish:
- Contracción: Most resins shrink 2% ~ 8% Durante el curado. High-shrinkage resins (P.EJ., general-purpose resin) pull the surface unevenly, leading to Ra 2 μm ~ 5 μm. Low-shrinkage resins (P.EJ., dental-specific resin) shrink < 2%, producing Ra < 1 μm.
- Tipo de resina:
- General-purpose resin: Real academia de bellas artes 2 μm ~ 5 μm; affordable but rough.
- High-precision resin (P.EJ., for medical models): Real academia de bellas artes < 1 μm; formulated for minimal shrinkage.
- Flexible resin: Slightly higher roughness (Real academia de bellas artes 1.5 μm ~ 3 μm) due to elastic properties.
(4) Post-Processing Processes
Post-processing is the final step to refine surface roughness—even a rough printed part can become smooth with the right treatments:
| Paso postprocesado | Roughness Reduction (Real academia de bellas artes) | Rango de costos (RMB/Piece) | Mejor para |
| Simple Cleaning (Isopropyl Alcohol) | 0.5 μm ~ 1 μm | 5 ~ 10 | Removes uncured resin; suavidad básica |
| Lijado (1200 ~ 2000 Grit Sandpaper) | 2 μm ~ 4 μm | 20 ~ 50 | Eliminates layer lines; Ra drops from 5 μm a < 1 μm |
| Pulido (Pasta de pulido) | 0.3 μm ~ 0.5 μm | 30 ~ 80 | Mirror-like finish; ideal for jewelry |
| Secondary UV Curing | 0.2 μm ~ 0.5 μm | 10 ~ 30 | Reduces stickiness; improves surface uniformity |
| Pulverización (Clear Coat) | 0.5 μm ~ 1 μm | 40 ~ 100 | Fills micropores; adds protection |
3. Surface Roughness Standards for Practical Applications
Different use cases require different levels of smoothness. Below are common applications and their recommended roughness:
| Application Type | Required Roughness (Real academia de bellas artes) | Post-Processing Needed? | Razonamiento clave |
| Basic Prototypes (P.EJ., part fit checks) | 2 μm ~ 5 μm | No | Smoothness isn’t critical; saves time/cost |
| Aesthetic Parts (P.EJ., custom figurines) | 1 μm ~ 2 μm | Sí (Lijado + Pulido) | Visible surface quality matters |
| Modelos médicos (P.EJ., coronas dentales) | 0.5 μm ~ 1 μm | Sí (High-Precision Polishing) | Prevents bacterial growth; ensures biocompatibility |
| Joyas (P.EJ., colgantes) | < 1 μm | Sí (Pulido + Clear Coat) | Mirror finish enhances appearance |
| Partes funcionales (P.EJ., engranajes pequeños) | 1 μm ~ 2 μm | Sí (Lijado) | Reduce la fricción; improves part longevity |
4. 5 Step-by-Step Tips to Improve Light-Cured Surface Roughness
If your parts are too rough, follow these actionable steps to optimize smoothness:
- Choose the right technology: Use industrial-grade SLA or 4K DLP for Ra < 1 μm; avoid low-resolution DLP machines for high-detail parts.
- Set thin, but not too thin, capas: Comenzar con 0.05 capas mm (balances smoothness and speed); usar 0.025 mm for critical parts.
- Select low-shrinkage resin: Opt for dental or high-precision resin instead of general-purpose resin to reduce surface warping.
- Master exposure time: Test 3–5 exposure times (P.EJ., 4s, 5s, 6s) to find the sweet spot—avoid under/overexposure.
- Invest in post-processing: For Ra < 1 μm, sand with 1200 papel de lija, then polish with a microfiber cloth and polishing paste.
Yigu Technology’s Perspective on Light-Cured Surface Roughness
En la tecnología yigu, creemos balance between precision, costo, y necesidades de aplicación is key to managing light-cured surface roughness. Many clients overspend on ultra-thin layers or expensive post-processing when their parts don’t require it—for example, usando 0.025 mm layers for basic prototypes (unnecessary for Ra 2 μm ~ 5 μm). Our team helps clients match parameters to their use case: for dental models, we recommend industrial SLA + low-shrinkage resin + high-precision polishing (achieves Ra 0.5 μm ~ 1 μm); para prototipos, sugerimos 0.1 capas mm + no post-processing (salvamentos 30% ~ 50% of time/cost). We also provide resin testing kits to let clients compare shrinkage and roughness before full-scale production—ensuring they get the right smoothness without overpaying.
Preguntas frecuentes
- Can DLP ever be smoother than SLA for light-cured parts?
Yes—high-resolution 4K DLP machines (with pixel sizes < 0.01 milímetros) can reach Ra ~ 1 μm, matching mid-grade SLA machines. Sin embargo, industrial-grade SLA (with smaller laser spots) still outperforms DLP for ultra-smooth surfaces (Real academia de bellas artes < 1 μm).
- Why does overly thin layer thickness (P.EJ., < 0.02 milímetros) increase roughness?
Thinner layers require more frequent resin refilling, which can cause uneven resin levels across the build plate. This leads to inconsistent curing and visible surface defects, pushing Ra up by 1 μm ~ 2 μm compared to 0.025 capas mm.
- How much does post-processing (lijado + pulido) reduce roughness?
For a part with initial Ra 5 μm (de 0.1 capas mm + general resin), sanding with 1200 grit sandpaper can drop Ra to 1 μm ~ 2 μm. Adding polishing paste further reduces it to < 1 μm—total roughness reduction of 80% ~ 90%.