3D Impresión Postprocesamiento: A Complete Guide to MJF and SLS Parts

Si trabajas con MJF (Fusión de chorro múltiple) o SLSS (Sinterización láser selectiva) 3D impresión, you know that the printed part isn’t the final product. Post-processing is key to unlocking their full potential—whether you need a smooth surface, better water resistance, or electrical conductivity. This guide breaks down every critical post-processing step for MJF and SLS parts, con ejemplos del mundo real, datos, y consejos para resolver desafíos comunes.

1. Understanding MJF and SLS: Por qué es importante

Primero, let’s recap: both MJF and SLS are Tecnologías de impresión 3D a base de polvo that use thermoplastics (like nylon PA12) or elastomers. A diferencia de FDM (Modelado de deposición fusionada), they don’t need support structures—but their raw printed parts still have limitations:

• Rough surfaces from leftover powder
• Porosity that affects water tightness
• Opciones de color limitadas (MJF prints gray; SLS prints white/gray)
• Basic mechanical properties (no conductivity or extra hardness)

Post-processing fixes these issues. A continuación se muestra un desglose detallado de los métodos más efectivos., con pros, contras, and real use cases.

2. Essential Post-Processing Steps for MJF & SLS Parts

We’ve organized the most common processes by goal—from cleaning to enhancing performance. Each section includes data and examples to help you choose.

2.1 Powder Removal & Disparó a Peening: The First Step

Every MJF/SLS part starts with leftover powder (trapped in crevices or on the surface). Este paso no es negociable.

Cómo funciona:

1. Powder removal: Use a soft brush or compressed air to blow loose powder off the part. For tight spaces (like hollow tubes), use a vacuum nozzle.
2. Disparó a Peening: Blast the part with high-pressure compressed air mixed with tiny glass beads (100–150 μm in size). This removes remaining powder and smooths minor surface roughness.

Datos clave:

Ejemplo real:

A manufacturer of SLS nylon PA12 gears used shot peening to remove powder from tooth gaps. The process cut assembly time by 40% (no more manual picking of powder) and reduced friction between gears by 15%.

Pros:

• Fast and low-cost (no special chemicals)
• No effect on part size or shape
• Works for all MJF/SLS geometries

Contras:

• Only removes powder (doesn’t fix deep scratches or add color)

2.2 Media Tumbling (Pulido de vibración): For a Satin Finish

If you need a smooth, matte surface (like for consumer products or medical devices), media tumbling is ideal.

Cómo funciona:

Place 10–50 parts in a vibrating drum filled with small ceramic chips (3–5 mm) and a mild detergent. Let it run for 4–8 hours—the chips gently rub against the part, Reducción de aspereza.

Ejemplo real:

A startup making SLS nylon watch cases used media tumbling. The process turned rough, powdery surfaces into a satin finish (Ra from 8 μm a 2 μm) and allowed them to process 30 cases at once—saving 60% of labor time vs. hand polishing.

Pros & Contras (De un vistazo):

2.3 Tintura: Add Color Without Altering Size

Dyeing is the cheapest way to add color to MJF and SLS parts—perfect for branding or aesthetic needs.

Cómo funciona:

Immerse parts in a heated water bath (60–80 ° C) with acid dyes. Let them soak for 10–15 minutes (longer for darker colors). The dye penetrates the surface but not the core.

Critical Differences: MJF VS. SLSS

Ejemplo real:

Una compañía de juguetes teñida 500 SLS nylon PA12 figurines green. They processed 100 at a time, costo \(0.20 per part—far cheaper than painting (\)1.50 por parte). The only downside: a scratch on the figurine revealed the white base (since dye only goes 0.5 mm profundo).

Pros:

• Bajo costo (\(0.10- )0.30 por parte)
• No effect on part size or weight
• Rápido (10–15 minutes per batch)

Contras:

• Dye wears off with heavy use (solo 0.5 mm profundo)
• Doesn’t smooth surfaces (rough parts stay rough)

2.4 Cuadro: For Gloss, Metallic Sheen, or Extra Protection

Painting goes beyond color—it adds physical benefits like water resistance and scratch protection.

Cómo funciona:

1. Pretratamiento: Clean the part with alcohol to remove oil/dust (crítico para la adhesión).
2. Cuadro: Apply 3–5 thin coats of paint (en lugar de 1 thick coat) because MJF/SLS parts are porous. Use acrylic or enamel paints for best results.
3. Curación: Let each coat dry for 1–2 hours before applying the next.

Ejemplo real:

An automotive supplier painted MJF nylon PA12 sensor housings with a metallic silver paint. The paint added a glossy finish (popular with customers) and improved water resistance—testing showed the housings could withstand 500 hours of rain without leaking (VS. 200 hours for uncoated parts).

Pros:

• Adds gloss, metallic, or matte finishes
• Improves water tightness and scratch resistance
• Works for both MJF and SLS parts

Contras:

• Labor-intensive (parts must be painted one by one)
• Pre-treatment is critical (bad cleaning = paint peeling)
• Adds minor weight (0.5–1 g per part)

2.5 Watertight Coatings: For Sealing Porous Parts

While raw MJF/SLS parts have basic water resistance, coatings like silicone or acrylate make them fully watertight—ideal for underwater or medical devices.

Key Coating Options:

Ejemplo real:

A medical device company used silicone coating on SLS nylon PA12 insulin pump reservoirs. The coating made the reservoirs 100% watertight—no leakage even when dropped in water for 30 días. It also didn’t affect the part’s flexibility (critical for pump use).

Pros:

• Excellent water resistance
• Silicone coatings preserve flexibility

Contras:

• Recubrimientos más gruesos (0.1–0.3 mm) may affect small part dimensions
• Requires curing time (2–4 hours for silicone)

2.6 Metal Plating: For Strength and Conductivity

Metal plating is for high-performance parts—think aerospace components or electrical connectors that need extra strength or conductivity.

Cómo funciona:

1. Deberes: Clean the part and apply a thin conductive layer (like graphite) because plastic isn’t conductive.
2. Electro Excripción: Submerge the part in a solution with dissolved metal (cobre, níquel, oro, etc.). Pass an electric current—metal particles stick to the part’s surface.

Common Metal Options:

Ejemplo real:

An electronics firm nickel-plated SLS nylon PA12 connectors. The plating increased the part’s tensile strength by 30% and made it conductive—perfect for linking circuit boards. La desventaja: each connector cost \(5 to plate (VS. \)1 to paint).

Pros:

• Boosts strength and conductivity
• Creates a high-quality, acabado duradero

Contras:

• Caro (3–10x cost of painting)
• Adds weight (5–10% of part weight)

3. Yigu Technology’s Perspective on MJF/SLS Post-Processing

En la tecnología yigu, we’ve supported hundreds of clients in optimizing MJF and SLS post-processing. Our experience shows that choosing the right process depends on three factors: end-use, presupuesto, and volume. Por ejemplo, small-batch consumer products (como fundas telefónicas) benefit from media tumbling + tintura (cost-effective and fast), while medical devices need watertight coatings + quality checks. We also recommend combining processes—e.g., shot peening followed by painting—to get both smoothness and protection. By aligning post-processing with your part’s purpose, you can reduce waste and improve performance.

4. Preguntas frecuentes: Common Questions About MJF/SLS Post-Processing

Q1: Can I skip powder removal if my MJF part looks clean?

No. Even if the surface looks clean, powder trapped in crevices (como agujeros o ranuras) can cause cracking or warping over time. Always do shot peening after brush/vacuum removal.

Q2: Why can’t MJF parts be dyed bright colors (P.EJ., red or green)?

MJF parts have a jet-black core. Bright dyes can’t cover this—they’ll look dull or uneven. Stick to black dye for MJF; SLS parts (white/gray core) work with any bright color.

Q3: Is metal plating worth the cost for non-aerospace parts?

Depende de tus necesidades. If you need conductivity (P.EJ., electrónica) or extra strength (P.EJ., herramientas industriales), Sí. For basic parts (P.EJ., corchetes), painting or media tumbling is a cheaper alternative.