Création d'un plastic injection molding prototype is a critical step in product development—it lets you test design feasibility, Valider les performances, and avoid costly mistakes in mass production. Contrairement aux pièces produites en masse, prototypes prioritize speed, cost-efficiency, et l'adaptabilité, 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
Choisir le bon matériau est le premier (and often make-or-break) step for prototypes. The goal is to balance Propriétés des matériaux with prototype goals—whether you’re testing durability, apparence, ou coût. Here’s how to navigate key choices:
| Catégorie de matériel | Exemples clés | Key Considerations for Prototypes |
| Thermoplastique | Pp, Abs, PC, Nylon, ANIMAL DE COMPAGNIE | Most common for prototypes—melt and re-solidify, facile à ajuster. Ideal for testing form, ajuster, and basic function. |
| Thermosets | Époxy, Résines phénoliques | Harden permanently after molding—good for high-heat or chemical-resistance tests. Less common for prototypes (hard to modify). |
| Additifs | Remplissage (fibre de verre), Stabilisateurs UV, retardateurs de flamme | Add only if the prototype needs to mimic final part performance (Par exemple, 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. |
Pour la pointe: Prioriser rentabilité 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) pour éviter le gaspillage. Aussi, check densité (affects part weight) et débit (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 & Conseils
- Conception de pièces: Keep it simple—avoid overcomplicating with unnecessary features (Par exemple, intricate logos) in early prototypes. Focus on testing the part’s core function.
- Épaisseur de paroi: Viser 1-3 MM (uniform across the part). Murs plus minces (<1 MM) cause short shots; thicker walls (>3 mm) lead to sink marks. Use gradual transitions if thickness must change.
- Angles de projet: Ajouter 1-3 degrees to all vertical surfaces. This lets the prototype eject smoothly from the mold—no more stuck parts or scratches.
- Côtes & Patrons: Côtes (for stiffness) should be 0.5x the wall thickness; les patrons (Pour les vis) should have a diameter 2x the screw size. Ajouter les filets (radius = 0.5 MM) to avoid stress cracks.
- Sous-dépouille: Minimize them! Sous-dépouille (Par exemple, side grooves) require complex mold slides, which increase prototype cost and lead time. Si nécessaire, use temporary solutions like post-machining.
- Tolérances: Loosen tolerances for early prototypes (±0.1 mm is enough for fit tests). Tolérances étroites (<± 0,05 mm) add cost and slow production.
Design Validation Tools
Before finalizing the design:
- Utiliser CAD Modelling (Par exemple, Solide, Fusion 360) to create 3D models—share these with your mold maker to avoid miscommunication.
- Courir Mold Flow Simulation (Par exemple, Autodesk Moldflow) to test resin flow. This catches issues like air traps or uneven filling early.
- Pour les pièces à stress élevé (Par exemple, supports automobiles), utiliser Analyse par éléments finis (Fea) to test strength—this avoids building prototypes that fail under load.
3. Mold Preparation for Prototypes
Moules prototypes (called “soft tools”) are simpler and cheaper than mass-production molds. They’re often made from aluminum (au lieu de l'acier) to speed up machining. Voici le processus clé:
Mold Components & Étapes de préparation
| Composant | But | Prototype-Specific Tips |
| Mold Base | Provides structure for the mold | Use standard-sized aluminum bases (Par exemple, 150×150 MM) pour réduire les coûts. |
| Cavités & 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. |
| Ejector Pins | Push the prototype out of the mold | Utiliser 2-4 petites épingles (3-5 diamètre mm) — place them near thick areas to avoid warping. |
| Canaux de refroidissement | 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 (point de fusion >220° C). Aluminum retains heat well, so extra heating is rarely needed. |
Mold Making Process
- Mold Machining: Use CNC milling for simple shapes; utiliser GED (Usinage à décharge électrique) only for fine details (Par exemple, petits trous). Aluminum machines 5x faster than steel—perfect for quick prototypes.
- Mold Polishing: Polish cavities to a #4 finition (mat) Pour les prototypes fonctionnels. High-gloss finishes (#8) are only needed for appearance tests.
- Assemblage du moule: Assemble components loosely first—test fit with a dummy resin (Par exemple, cire) to ensure alignment. Tighten screws only after test fitting.
- Mold Testing: Courir 5-10 test shots with scrap resin. Check for leaks, désalignement, 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 parties) and adjust parameters on the fly. Here’s how to execute it smoothly:
Key Machine Settings (for ABS Prototype Example)
| Paramètre | Plage optimale | Pourquoi cela compte pour les prototypes |
| Clamping Force | 50-100 tonnes | Lower force works for small prototypes—avoids damaging the aluminum mold. |
| Pression d'injection | 60-90 MPA | Too high = flash (excess resin); too low = short shots. Start low and increase if needed. |
| Faire fondre | 210-240° C | Keep 10-15°C lower than mass production—prevents resin degradation in small batches. |
| Temps de cycle | 30-60 secondes | Longer than mass production (gives aluminum molds time to cool). Rushing leads to warped parts. |
| Vitesse de vis | 60-100 RPM | Slow speed mixes resin evenly without generating excess heat. |
| Drying Process | 80° C pour 2-3 heures (pour les abdos) | Critical for resins like nylon or PC—moisture causes bubbles. Skip only for dry resins like PP. |
Step-by-Step Molding Workflow
- Alimentation des matériaux: Charger 1-2 kg of resin into the hopper (small batches reduce waste). Add a few pellets of colorant if needed.
- Conception de buse: Use a small-diameter nozzle (3-5 MM) to fill narrow prototype cavities. Keep the nozzle 1-2 mm from the mold to avoid leaks.
- Vitesse d'injection: Start at 40-60 mm / s. If the part has thin walls, increase to 70-80 mm/s to avoid short shots.
- Packing Pressure: Appliquer 80-90% of injection pressure for 2-3 secondes. This fills any small gaps in the prototype.
- Temps de refroidissement: Let the mold cool for 15-25 secondes (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. Post-traitement facultatif
| Tâche | But | Quand utiliser |
| Deburring/Deflashing | Remove excess resin from edges/parting lines | Always do this—sharp burrs ruin fit tests. Use a hand file (pour les petits lots) or rotary brush. |
| Garniture | Cut off runner systems (the plastic channels that feed resin) | Always do this—runners make prototypes hard to test. Use scissors (for soft resins) ou une scie à bande. |
| Usinage (Perçage/taraudage) | Add holes or threads for assembly | Only if testing assembly (Par exemple, attaching the prototype to another part). Use a handheld drill for small holes. |
| Peinture/Placage | Improve appearance | Only for appearance tests (Par exemple, showing the prototype to stakeholders). Utiliser de la peinture en aérosol (dries in 30 minutes) for quick results. |
| Assemblée | Join multiple prototype parts | Utiliser Soudage à ultrasons (rapide, no adhesives) ou liaison adhésive (faible coût) pour les petits lots. Avoid rivets (permanent, hard to modify). |
Pour la pointe: Pour les prototypes fonctionnels, skip painting/plating—focus on deburring and trimming. For appearance prototypes, utiliser impression (Par exemple, 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
- Pièces automobiles: Test fit of interior components (Par exemple, Clips de tableau de bord) or durability of small parts (Par exemple, poignées de porte).
- Électronique grand public: Validate the size of phone cases or the fit of charging port covers.
- Dispositifs médicaux: Test the ergonomics of syringes or the compatibility of plastic parts with liquids.
- Conditionnement: Check if a bottle prototype holds liquid without leaking or if a lid seals properly.
- Jouets: Test safety (Par exemple, no small parts that break off) et durabilité (Par exemple, withstands dropping).
- Composants aérospatiaux: Test lightweight parts (Par exemple, supports en plastique) for strength under low pressure.
Prototype Stages in Product Development
- Concept Prototype: Early-stage, faible coût (Par exemple, Pièces d'abs) to test basic form.
- Prototype fonctionnel: Mid-stage, uses final material (Par exemple, PC) to test performance.
- Pre-Production Prototype: Late-stage, identical to mass-produced parts—used for final validation.
La vue de la technologie Yigu
À la technologie Yigu, we know prototype success hinges on balancing speed, coût, and clarity of goals. For plastic injection molding prototypes, we prioritize aluminum molds (rapide, 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, Réduire le temps de reprise par 30%. Our focus is on delivering prototypes that solve real problems—whether it’s testing a fit, validating a design, or impressing stakeholders.
FAQ
- Q: How long does it take to make a plastic injection molding prototype?
UN: 1-2 weeks for simple prototypes (aluminum mold + Pièces d'abs). Prototypes complexes (with undercuts or FEA testing) prendre 3-4 semaines.
- Q: Can I use the same mold for prototype and mass production?
UN: Rarely—prototype molds are aluminum (doux, wears out after 1,000+ coups de feu), while mass-production molds are steel (dur, dure 100,000+ coups de feu). 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?
UN: \(500-\)2,000 for a simple prototype (aluminum mold + 10-50 parties). Costs rise to \(3,000-\)5,000 Pour des conceptions complexes (EDM machining, FEA testing, or final materials like PC).