Creando un plastic injection molding prototype is a critical step in product development—it lets you test design feasibility, validar el rendimiento, and avoid costly mistakes in mass production. A diferencia de las partes producidas en masa, prototypes prioritize speed, rentabilidad, y adaptabilidad, while still following core injection molding principles. Below is a complete, actionable breakdown of the prototype development process, from material pick to final application.
1. Material Selection for Prototypes
Elegir el material correcto es el primero (and often make-or-break) step for prototypes. The goal is to balance propiedades del material with prototype goals—whether you’re testing durability, apariencia, o costo. Here’s how to navigate key choices:
| Categoría de material | Ejemplos clave | Key Considerations for Prototypes |
| Termoplástico | PÁGINAS, Abdominales, ordenador personal, Nylon, MASCOTA | Most common for prototypes—melt and re-solidify, fácil de ajustar. Ideal for testing form, adaptar, and basic function. |
| Termossets | Epoxy, Resinas fenólicas | Harden permanently after molding—good for high-heat or chemical-resistance tests. Less common for prototypes (hard to modify). |
| Aditivos | Relleno (fibra de vidrio), Estabilizadores UV, Retardantes de la llama | Add only if the prototype needs to mimic final part performance (P.EJ., glass fiber for stiffness). Skip non-essential additives to cut costs. |
| Colorants | Liquid dyes, masterbatches | Use only if appearance testing is critical. Clear or natural resins save time and money for functional prototypes. |
Para la punta: Priorizar rentabilidad for early-stage prototypes—opt for common resins like PP or ABS instead of high-end materials like PEEK. For supplier selection, choose vendors who offer small batch sizes (1-5 kilos) to avoid waste. También, check densidad (affects part weight) y caudal (ensures the resin fills small prototype mold cavities easily).
2. Design Considerations for Prototype Success
Prototype design should be “mold-friendly” to speed up production and reduce defects. Even small design tweaks can save days of rework. Here’s a checklist of critical factors:
Core Design Elements & Consejos
- Part Design: Keep it simple—avoid overcomplicating with unnecessary features (P.EJ., intricate logos) in early prototypes. Focus on testing the part’s core function.
- Espesor de la pared: Apuntar 1-3 milímetros (uniform across the part). Paredes más delgadas (<1 milímetros) cause short shots; thicker walls (>3 mm) lead to sink marks. Use gradual transitions if thickness must change.
- Ángulos de borrador: Agregar 1-3 degrees to all vertical surfaces. This lets the prototype eject smoothly from the mold—no more stuck parts or scratches.
- Costillas & Jefe: Costillas (for stiffness) should be 0.5x the wall thickness; bosses (para tornillos) should have a diameter 2x the screw size. Agregar filetes (radius = 0.5 milímetros) to avoid stress cracks.
- Subvenciones: Minimize them! Subvenciones (P.EJ., side grooves) require complex mold slides, which increase prototype cost and lead time. Si es necesario, use temporary solutions like post-machining.
- Tolerancias: Loosen tolerances for early prototypes (±0.1 mm is enough for fit tests). Tolerancias apretadas (<± 0.05 mm) add cost and slow production.
Design Validation Tools
Before finalizing the design:
- Usar CAD Modelling (P.EJ., Solidworks, Fusión 360) to create 3D models—share these with your mold maker to avoid miscommunication.
- Correr Simulación de flujo de moho (P.EJ., Autodesk Moldflow) to test resin flow. This catches issues like air traps or uneven filling early.
- Para piezas de alto estrés (P.EJ., soportes automotrices), usar Análisis de elementos finitos (Fea) to test strength—this avoids building prototypes that fail under load.
3. Mold Preparation for Prototypes
Moldes prototipo (called “soft tools”) are simpler and cheaper than mass-production molds. They’re often made from aluminum (instead of steel) to speed up machining. Aquí está el proceso clave:
Mold Components & Pasos de preparación
| Componente | Objetivo | Prototype-Specific Tips |
| Mold Base | Provides structure for the mold | Use standard-sized aluminum bases (P.EJ., 150×150 milímetros) to cut costs. |
| Cavidades & Cores | Shape the prototype (cavity = outer surface; core = inner surface) | For single-cavity molds (most prototypes), machine cavities directly into the aluminum—faster than multi-cavity molds. |
| Alfileres de eyectores | Push the prototype out of the mold | Usar 2-4 alfileres (3-5 diámetro mm) — place them near thick areas to avoid warping. |
| Canales de enfriamiento | Cool the mold to set the resin | Drill simple straight channels (instead of complex curved ones) — aluminum cools quickly, so basic channels work. |
| Heating Elements | Warm the mold (for resins with high melting points) | Skip unless using resins like PC (punto de fusión >220° C). Aluminum retains heat well, so extra heating is rarely needed. |
Mold Making Process
- Mold Machining: Use CNC milling for simple shapes; usar electroerosión (Mecanizado de descarga eléctrica) only for fine details (P.EJ., pequeños agujeros). Aluminum machines 5x faster than steel—perfect for quick prototypes.
- Mold Polishing: Polish cavities to a #4 finalizar (mate) para prototipos funcionales. High-gloss finishes (#8) are only needed for appearance tests.
- Mold Assembly: Assemble components loosely first—test fit with a dummy resin (P.EJ., wax) to ensure alignment. Tighten screws only after test fitting.
- Pruebas de molde: Correr 5-10 test shots with scrap resin. Check for leaks, desalineación, or stuck parts—fix issues before running the actual prototype batch.
4. The Injection Molding Process for Prototypes
Prototype injection molding focuses on speed and flexibility—you’ll often run small batches (10-50 regiones) and adjust parameters on the fly. Here’s how to execute it smoothly:
Key Machine Settings (for ABS Prototype Example)
| Parámetro | Rango óptimo | Por qué importa para los prototipos |
| Clamping Force | 50-100 montones | Lower force works for small prototypes—avoids damaging the aluminum mold. |
| Inyección | 60-90 MPA | Too high = flash (excess resin); too low = short shots. Start low and increase if needed. |
| Temperatura de fusión | 210-240° C | Keep 10-15°C lower than mass production—prevents resin degradation in small batches. |
| Tiempo de ciclo | 30-60 artículos de segunda clase | Longer than mass production (gives aluminum molds time to cool). Rushing leads to warped parts. |
| Velocidad del tornillo | 60-100 rpm | Slow speed mixes resin evenly without generating excess heat. |
| Drying Process | 80° C para 2-3 horas (para ABS) | Critical for resins like nylon or PC—moisture causes bubbles. Skip only for dry resins like PP. |
Step-by-Step Molding Workflow
- Alimentación por material: Carga 1-2 kg of resin into the hopper (small batches reduce waste). Add a few pellets of colorant if needed.
- Diseño de boquilla: Use a small-diameter nozzle (3-5 milímetros) to fill narrow prototype cavities. Keep the nozzle 1-2 mm from the mold to avoid leaks.
- Velocidad de inyección: Start at 40-60 mm/s. If the part has thin walls, increase to 70-80 mm/s to avoid short shots.
- Packing Pressure: Aplicar 80-90% of injection pressure for 2-3 artículos de segunda clase. This fills any small gaps in the prototype.
- Tiempo de enfriamiento: Let the mold cool for 15-25 artículos de segunda clase (aluminum cools fast!). Eject the part only when it’s cool to the touch.
Common Issue Fix: If the prototype has flash (excess resin), reduce injection pressure by 5-10 MPA. If it has short shots, increase melt temperature by 5-10°C.
5. Post-Processing and Finishing for Prototypes
Post-processing turns raw molded parts into usable prototypes. Focus on tasks that support your test goals—skip unnecessary steps to save time.
Essential vs. Postprocesamiento opcional
| Tarea | Objetivo | When to Use |
| Deburring/Deflashing | Remove excess resin from edges/parting lines | Always do this—sharp burrs ruin fit tests. Use a hand file (para lotes pequeños) or rotary brush. |
| Guarnición | Cut off runner systems (the plastic channels that feed resin) | Always do this—runners make prototypes hard to test. Use scissors (for soft resins) o una sierra de banda. |
| Mecanizado (Perforación/roscado) | Add holes or threads for assembly | Only if testing assembly (P.EJ., attaching the prototype to another part). Use a handheld drill for small holes. |
| Painting/Plating | Improve appearance | Only for appearance tests (P.EJ., showing the prototype to stakeholders). Use pintura en aerosol (dries in 30 minutos) for quick results. |
| Asamblea | Join multiple prototype parts | Usar soldadura ultrasónica (rápido, no adhesives) o enlace adhesivo (bajo costo) para lotes pequeños. Avoid rivets (permanent, hard to modify). |
Para la punta: Para prototipos funcionales, skip painting/plating—focus on deburring and trimming. For appearance prototypes, usar impresión (P.EJ., pad printing) for logos instead of expensive plating.
6. Applications and Uses of Injection Molding Prototypes
Prototypes are used across industries to de-risk product development. Here’s how different sectors leverage them:
Industry-Specific Uses
- Piezas automotrices: Test fit of interior components (P.EJ., clips de tablero) or durability of small parts (P.EJ., manijas de las puertas).
- Electrónica de consumo: Validate the size of phone cases or the fit of charging port covers.
- Dispositivos médicos: Test the ergonomics of syringes or the compatibility of plastic parts with liquids.
- Embalaje: Check if a bottle prototype holds liquid without leaking or if a lid seals properly.
- Juguetes: Test safety (P.EJ., no small parts that break off) y durabilidad (P.EJ., withstands dropping).
- Componentes aeroespaciales: Test lightweight parts (P.EJ., corchetes) for strength under low pressure.
Prototype Stages in Product Development
- Concept Prototype: Early-stage, bajo costo (P.EJ., Piezas de abdominales) to test basic form.
- Prototipo funcional: Mid-stage, uses final material (P.EJ., ordenador personal) to test performance.
- Pre-Production Prototype: Late-stage, identical to mass-produced parts—used for final validation.
Vista de la tecnología de Yigu
En la tecnología yigu, we know prototype success hinges on balancing speed, costo, and clarity of goals. For plastic injection molding prototypes, we prioritize aluminum molds (rápido, rentable) and common thermoplastics for early stages, then shift to final materials for functional tests. We integrate CAD, Mold Flow, and FEA to catch issues before molding, Cortar el tiempo de retrabajo por 30%. Our focus is on delivering prototypes that solve real problems—whether it’s testing a fit, validating a design, or impressing stakeholders.
FAQs
- q: How long does it take to make a plastic injection molding prototype?
A: 1-2 weeks for simple prototypes (aluminum mold + Piezas de abdominales). Prototipos complejos (with undercuts or FEA testing) llevar 3-4 semanas.
- q: Can I use the same mold for prototype and mass production?
A: Rarely—prototype molds are aluminum (suave, wears out after 1,000+ tiros), while mass-production molds are steel (duro, duración 100,000+ tiros). Use the prototype mold to refine the design, then make a steel mold for production.
- q: How much does a plastic injection molding prototype cost?
A: \(500-\)2,000 for a simple prototype (aluminum mold + 10-50 regiones). Costs rise to \(3,000-\)5,000 Para diseños complejos (EDM machining, FEA testing, or final materials like PC).