Plastic compound mold processing—also known as vacuum injection molding or soft mold casting—is a cost-effective manufacturing method for producing plastic parts using reusable silicone-based molds. Unlike traditional steel mold processes, it prioritizes speed, flexibilidad, and detail replication, making it ideal for small-batch production and product development. This article breaks down its core definitions, step-by-step workflow, selecciones de materiales, ventajas, and limitations—with clear comparisons and real-world examples to help you optimize the process for your projects.
1. Definición de núcleo & Principios clave
Antes de sumergirse en el proceso, it’s critical to understand what makes plastic compound mold processing unique and how it differs from traditional methods.
| Aspecto | Plastic Compound Mold Processing | Traditional Steel Injection Molding |
| Material de molde | Primarily silicone rubber (flexible, elástico, and detail-retaining). | Rigid materials like acero o aluminio (highly durable but costly to machine). |
| Principio fundamental | Replicates parts by pouring liquid plastic into a silicone mold (created from a prototype), then curing and demolding. | Injects molten plastic into a steel mold under high pressure (10–150 MPA) para la producción en masa. |
| Batch Suitability | Ideal para lotes pequeños (10–500 unidades) y prototipos. | Designed for mass production (10,000+ unidades) to offset high mold costs. |
| Ventaja clave | Low mold cost, cambio rápido, and ability to replicate complex shapes/textures. | Alta eficiencia de producción, superior part accuracy, and long mold life (100,000+ ciclos). |
Key Question: Why choose plastic compound mold processing?
For projects where speed and cost matter more than ultra-high volume—such as new product testing, niche market parts, or custom crafts—silicone-based molds eliminate the need for expensive steel tooling, cutting both time and upfront investment.
2. Step-by-Step Processing Workflow
Plastic compound mold processing follows a linear, repeatable workflow that starts with a prototype and ends with finished plastic parts. Each step directly impacts the final part’s quality and the mold’s durability.
2.1 Escenario 1: Prototype Preparation (The “Master Model”)
The prototype serves as the template for the silicone mold—its quality determines the detail and accuracy of all subsequent parts.
| Método de fabricación de prototipos | Características clave | Ideal para |
| 3D impresión (SLA/DLP) | – Alta precisión (± 0.05 mm) for intricate details (P.EJ., logotipos, texturas).- Acabado superficial liso (RA 0.8–1.6 μm) reduces post-processing.- Cambio rápido (12–24 hours for small parts). | Partes complejas: caparazones de dispositivos electrónicos (fundas telefónicas, TV remote casings), decorative items with fine patterns. |
| Mecanizado CNC | – Ultra-high accuracy (± 0.01 mm) for tight tolerances.- Suitable for hard materials (metal, plástico rígido, madera).- Ideal for flat or geometrically precise parts. | High-precision components: soportes automotrices, carcasa de dispositivos médicos, parts requiring strict dimensional consistency. |
| Hand Engraving/Crafting | – Low cost for simple shapes.- Flexible for one-of-a-kind designs.- No specialized equipment needed. | Simple decorative parts: custom keychains, small figurines, low-precision prototypes for visual testing. |
Sugerencia crítica: Ensure the prototype is clean and defect-free (no dust, aceite, o rayones). Even tiny flaws will be replicated in the silicone mold—for example, a dusty prototype will create a mold with embedded particles, ruining the finish of plastic parts.
2.2 Escenario 2: Fabricación de moho de silicona (The “Negative Template”)
This stage transforms the prototype into a reusable mold. Proper silicone mixing, torrencial, and curing are essential to avoid bubbles, lágrimas, or incomplete detail capture.
Paso 1: Mold Frame Setup
- Frame Selection: Choose a frame material (madera, plástico, o metal) large enough to fit the prototype with 5–10mm of space on all sides (ensures even silicone coverage).
- Caza de focas: Use masking tape or acrylic sealant to seal frame edges—prevents silicone leakage, which wastes material and distorts the mold shape.
- Prototype Positioning: Secure the prototype in the frame with clay or double-sided tape—keep it centered to ensure uniform silicone thickness.
Paso 2: Silicone Mixing
- Selección de material: Use two-component silicone rubber (Parte A: base; Part B: agente de curado) with a mixing ratio specified by the manufacturer (típicamente 1:1 by volume/weight for additive silicone, 10:1 for condensation silicone).
- Mixing Rules:
- Stir slowly and thoroughly (2–3 minutos) to avoid air bubbles—uneven mixing causes weak spots in the mold.
- Para lotes grandes, usar un máquina desgasificadora al vacío (1–2 minutos a las -0.1MPA) to remove trapped air—critical for parts with tiny details (P.EJ., 0.5ranuras de mm de ancho).
Paso 3: Vertido de silicona & Curación
- Técnica de vertido: Tilt the frame at a 45° angle and pour silicone slowly along the frame wall (no directamente sobre el prototipo)—reduces bubble formation. Para moldes gruesos (>10mm), usar vertido en capas: derramar 1/3 de la silicona, esperar 30 minutos para que las burbujas suban, luego agrega la siguiente capa.
- Parámetros de curado:
| Tipo de silicona | Temperatura de curado | Tiempo de curado (for 5mm Thickness) | Post-Curing Tip |
| Aditivo (Platinum-Cure) | 20°C–25°C | 2–4 horas | No post-curing needed; ready to demold once firm. |
| Condensation | 20°C–25°C | 4–8 horas | Cure for an extra 1 hour if mold is thicker than 10mm. |
| High-Temperature Resistant | 20°C–25°C (inicial); 80° C (post) | 6–10 horas (inicial); 2 horas (post) | Post-cure in an oven to activate heat resistance (hasta 200 ° C). |
Paso 4: Demolding the Prototype
- Una vez curado, gently peel the silicone mold from the prototype—silicone’s elasticity ensures easy removal without damaging either the mold or prototype.
- Trim excess silicone (destello) from mold edges with a sharp knife—creates a clean, precise mold for plastic casting.
2.3 Escenario 3: Plastic Part Production (The “Replica Process”)
Con el molde de silicona listo, this stage produces finished plastic parts through pouring, curación, and demolding.
Paso 1: Plastic Material Selection
Choose a material based on the part’s end-use (fortaleza, flexibilidad, resistencia al calor):
| Material de plástico | Propiedades clave | Aplicaciones ideales |
| Poliuretano (PUS) Resina | – Curado rápido (1–2 hours at 20°C).- Good wear resistance and flexibility (Shore A 30–80).- Bajo costo ($20–40 per kg). | Partes funcionales: Botones del control remoto del televisor, componentes de juguete, flexible gaskets, small electronic housings. |
| Resina epoxídica | – Alta fuerza (resistencia a la tracción: 50–80MPa) and chemical resistance.- A prueba de calor (120°C–180°C after curing).- Baja contracción (0.5–1%). | Partes estructurales: moldura automotriz, manejas de dispositivos médicos, parts requiring durability under stress. |
| Cloruro de polivinilo (CLORURO DE POLIVINILO) | – Low cost and good chemical stability.- Rigid or flexible variants available.- Suitable for food-contact parts (when food-grade). | Custom containers, adorno decorativo, low-stress household items. |
Paso 2: Torrencial & Curación
- Torrencial: Pour liquid plastic into the silicone mold slowly (use a small funnel for narrow openings) para evitar burbujas. For complex parts with internal cavities, usar sectional pouring: fill one section, esperar 10 minutes for partial curing, then fill the next—ensures full cavity coverage.
- Curación:
- Curado a temperatura ambiente: Resina PU (1–2 horas), resina epoxídica (4–6 horas).
- Curado acelerado: Use a low-temperature oven (50°C–60°C) para reducir el tiempo por 50% (P.EJ., epoxy resin cures in 2–3 hours).
Paso 3: Fundamento & Postprocesamiento
- Gently peel the silicone mold from the plastic part—silicone’s flexibility prevents cracking or deformation.
- Trim excess plastic (destello) with scissors or a utility knife. For better finish, sand the part with 400–800 grit sandpaper.
3. Advantages of Plastic Compound Mold Processing
This method solves key pain points for small-batch and prototyping projects:
| Categoría de ventaja | Beneficios clave | Ejemplo del mundo real |
| Bajo costo | – Silicone mold cost is 50–70% lower than steel molds (P.EJ., \(200 VS. \)5,000 for a small part mold).- No expensive machining equipment needed for mold production. | A startup producing 50 test samples of a new smartwatch casing saves $4,800 by using a silicone mold instead of steel. |
| Cambio rápido | – Entire process (prototype → mold → parts) takes 3–7 days, VS. 2–4 weeks for steel molds. | A consumer electronics company needs 20 TV remote prototypes for user testing—plastic compound processing delivers them in 4 días, enabling faster design iterations. |
| Complex Detail Replication | – Captures tiny textures (0.1mm -0.5 mm), superficies curvas, and internal structures that steel molds may struggle to replicate. | A jewelry brand replicates a hand-sculpted pendant with fine engravings—each plastic part retains the pendant’s intricate patterns, which would require costly steel mold machining. |
| Flexibilidad | – Easy to adjust mold design (P.EJ., modify a prototype and make a new silicone mold in 1–2 days).- Switch plastic materials or colors without changing the mold. | A phone case manufacturer tests 3 bandera (negro, blanco, azul) using the same silicone mold—no need for multiple molds, cutting color-testing costs by 60%. |
4. Limitaciones a considerar
While highly effective for specific use cases, plastic compound mold processing has constraints:
- Vida limitada del molde: Silicone molds last 20–500 ciclos (VS. 100,000+ for steel molds). Parts with sharp edges or high friction (P.EJ., clips de plástico) wear down molds faster—after 50 ciclos, a mold may start to lose detail.
- Lower Part Accuracy: Dimensional accuracy is ±0.1mm–±0.3mm (VS. ±0.01mm for steel injection molding). This is sufficient for most consumer parts but not for precision components like aerospace parts.
- Lower Production Efficiency: Each part requires manual pouring and demolding—production speed is 1–10 parts per hour (VS. 100+ parts per hour for steel injection molding). Para lotes superiores 500 unidades, it becomes slower and more costly than traditional methods.
5. Yigu Technology’s Perspective on Plastic Compound Mold Processing
En la tecnología yigu, we see plastic compound mold processing as a “development enabler”—it lets clients test designs fast and avoid overinvesting in unproven products. A common mistake we address is clients overusing it for large batches: one client tried to produce 2,000 phone cases with a silicone mold, only to face mold wear and inconsistent parts after 300 ciclos. We advised switching to steel molds for mass production, Guardarlos 40% en costos de retrabajo. Para prototipos, we recommend additive silicone (1:1 relación) for detail retention and PU resin for fast functional testing. Our key insight: This process shines when paired with a clear transition plan—use it for 10–500 units, then scale to steel molds if demand grows.
6. Preguntas frecuentes: Common Questions About Plastic Compound Mold Processing
Q1: Can I use plastic compound mold processing for high-temperature parts (P.EJ., parts exposed to 150°C)?
A1: Sí, but use heat-resistant materials. Elegir high-temperature silicone (service temp: 200° C - 300 ° C) for the mold and heat-resistant epoxy resin (cured temp: 120°C–180°C) para la parte. Test a sample first—expose it to 150°C for 24 hours to ensure no deformation. Avoid standard silicone (Temperatura máxima: 150° C) or PU resin (Temperatura máxima: 80° C) for high-heat applications.
Q2: How can I extend the life of my silicone mold?
A2: – Clean the mold with mild soap and water after each use (avoid harsh solvents like acetone, which break down silicone).- Apply a thin layer of silicone oil to the mold before pouring plastic—reduces friction and wear.- Guarde el molde en una fría, lugar seco (humedad <60%) and avoid folding or stretching it—prevents tears.
Q3: Are parts made via plastic compound mold processing suitable for food contact?
A3: Only if you use food-grade materials. Elegir food-safe silicone (certified by FDA or EU standards) for the mold and food-grade plastic resins (P.EJ., food-grade PU, CLORURO DE POLIVINILO, or epoxy). Regular materials may leach chemicals into food—always test the final part for compliance (P.EJ., FDA 21 CFR 177.2600 para resina) antes de usar.