O que afeta a rugosidade das superfícies fotopolimerizáveis ​​impressas em 3D? Um guia completo

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 Rá 0.5 μM a RA 5 μm depending on key factors. This guide breaks down typical roughness ranges, principais fatores de influência, 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 (Por exemplo, Fdm), but the exact roughness depends on technology type, parâmetros, e materiais. Below is a detailed breakdown of standard ranges:

Observação: Rá (Average Surface Roughness) is the most common metric—lower values mean smoother surfaces. Para referência, a polished metal surface has an Ra of ~0.02 μm, while a standard light-cured part (sem pós-processamento) 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) Tecnologia de impressão & 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 (Por exemplo, 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) Parâmetros de impressão

Even with the right equipment, poor parameter settings can ruin surface smoothness. The two most critical parameters are:

Espessura da camada

Thinner layers mean fewer visible layer lines, but overly thin layers can cause resin flow issues. Here’s how layer thickness impacts roughness:

Período de exposição

• Insufficient exposure: Resin doesn’t cure fully, leaving sticky, superfícies irregulares (Ra can jump to 4 μm ~ 6 μm).
• Overexposure: Resin shrinks excessively, causing warping or surface cracks (Ra increases by 1 μm ~ 2 μm).

Prática recomendada: Follow the resin manufacturer’s recommended exposure time (Por exemplo, 5 seconds per layer for standard resin).

(3) Resin Material Properties

Not all resins are equal—formulation affects shrinkage and surface finish:

• Encolhimento: Most resins shrink 2% ~ 8% durante a cura. High-shrinkage resins (Por exemplo, general-purpose resin) pull the surface unevenly, leading to Ra 2 μm ~ 5 μm. Low-shrinkage resins (Por exemplo, dental-specific resin) shrink < 2%, producing Ra < 1 μm.
• Tipo de resina:
• General-purpose resin: Rá 2 μm ~ 5 μm; affordable but rough.
• High-precision resin (Por exemplo, for medical models): Rá < 1 μm; formulated for minimal shrinkage.
• Flexible resin: Slightly higher roughness (Rá 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:

3. Surface Roughness Standards for Practical Applications

Different use cases require different levels of smoothness. Below are common applications and their recommended roughness:

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:

1. Choose the right technology: Use industrial-grade SLA or 4K DLP for Ra < 1 μm; avoid low-resolution DLP machines for high-detail parts.
2. Set thin, but not too thin, camadas: Comece com 0.05 camadas mm (balances smoothness and speed); usar 0.025 mm for critical parts.
3. Select low-shrinkage resin: Opt for dental or high-precision resin instead of general-purpose resin to reduce surface warping.
4. Master exposure time: Test 3–5 exposure times (Por exemplo, 4é, 5é, 6é) to find the sweet spot—avoid under/overexposure.
5. Invest in post-processing: For Ra < 1 μm, sand with 1200 Lixa de grão, then polish with a microfiber cloth and polishing paste.

Yigu Technology’s Perspective on Light-Cured Surface Roughness

Na tecnologia Yigu, acreditamos balance between precision, custo, and application needs 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 protótipos, we suggest 0.1 camadas mm + no post-processing (salva 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.

Perguntas frequentes

1. 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. No entanto, industrial-grade SLA (with smaller laser spots) still outperforms DLP for ultra-smooth surfaces (Rá < 1 μm).

2. Why does overly thin layer thickness (Por exemplo, < 0.02 milímetros) increase roughness?

Thinner layers require more frequent resin refilling, o que pode causar níveis irregulares de resina na placa de impressão. Isso leva a uma cura inconsistente e a defeitos superficiais visíveis, empurrando Ra para cima 1 μm ~ 2 μm em comparação com 0.025 camadas mm.

3. Quanto custa o pós-processamento (lixar + polimento) reduzir a rugosidade?

Para uma peça com Ra inicial 5 μm (de 0.1 camadas mm + resina geral), lixar com 1200 lixa de grão pode deixar Ra cair 1 μm ~ 2 μm. Adicionar pasta de polimento reduz ainda mais < 1 μm - redução total da rugosidade de 80% ~ 90%.