Moulage sous vide en silicone is a high-precision manufacturing process used to replicate complex parts—from electronic device shells to art prototypes—by eliminating air bubbles via vacuum pressure. The success of this process depends entirely on selecting the right materials, which include silicone molds, base prototypes, auxiliary agents, and casting resins. This article breaks down each material category with clear comparisons, technical specs, et applications du monde réel, helping you optimize vacuum casting for accuracy, durabilité, et rentable.
1. Core Silicone Mold Materials: The Foundation of Casting
Silicone is the heart of vacuum casting molds—its flexibility and detail-retaining ability ensure replicas match the original prototype. Materials are categorized by curing mechanism and performance, each suited to specific needs.
| Type en silicone | Caractéristiques clés | Curing Parameters | Applications idéales |
| Silicone à condensation | – Releases small molecules (ethanol/acetic acid) during curing.- Faible coût (30–50% cheaper than additive silicone).- Moderate shrinkage (2–3%), which may blur fine details.- Rivage une dureté: 20–40 (doux, Demolding facile). | – Mixing ratio: 100:2–5 (silicone:agent de durcissement).- Temps de durcissement: 4–8 heures (20°C–25°C).- No vacuum needed for mixing (but vacuum casting still requires bubble removal). | Simple parts with low precision demands: handicrafts, prototypes jouets, and non-critical decorative items (Par exemple, plastic plant pots). |
| Additif (Platinum-Cure) Silicone | – No small molecule release during curing.- Ultra-low shrinkage (0.1–0,5%)—critical for high-precision parts.- High durability (reusable 40–60 cycles, contre. 20–30 for condensation).- Rivage une dureté: 30–60 (versatile for soft/hard parts). | – Mixing ratio: 1:1 (by volume/weight—easy to measure).- Temps de durcissement: 2–4 heures (20°C–25°C; 1 hour at 50°C–60°C).- Requires vacuum defoaming (1–2 minutes à -0.1MPA) to avoid internal bubbles. | High-precision components: Shels de dispositif électronique (TV remote casings), pièces de dispositif médical (syringe nozzles), and automotive interior trim (boutons de tableau de bord). |
| High-Temperature Resistant Silicone | – Withstands post-casting heat (200° C - 300 ° C) for heat-curing resins.- Retains flexibility and shape at extreme temperatures.- Faible retrait (0.3–0,8%) and high tear resistance. | – Mixing ratio: 100:5 (silicone:agent de durcissement).- Temps de durcissement: 6–10 heures (20°C–25°C; 2–3 hours at 80°C).- Must be cured in a temperature-controlled oven to activate heat resistance. | High-heat casting scenarios: metal alloy replicas (low-melting tin-lead alloys), thermoset resin parts (epoxy cured at 120°C), and aerospace component prototypes. |
| Transparent Silicone | – Transmission lumineuse élevée (85–95% after curing)—lets you monitor casting material flow.- Available in both condensation and additive types (additive preferred for precision).- Similar mechanical properties to non-transparent counterparts. | – Same curing parameters as matching non-transparent silicone (Par exemple, 1:1 ratio for additive transparent).- Requires extra care to avoid dust (which reduces transparency). | Composants optiques: light diffusers, transparent device housings (Par exemple, LED lamp covers), and prototypes where internal casting defects need visual inspection. |
2. Base Prototype Materials: The “Original Model”
The prototype (ou maître modèle) defines the shape of the final replica. It must be durable enough to withstand silicone pouring and compatible with silicone (no chemical reactions).
| Matériau prototype | Traits clés | Compatibility with Silicone | Idéal pour |
| 3D-Printed Resins (SLA/DLP) | – Haute précision (± 0,05 mm) for complex details.- Surface lisse (RA 0,8–1,6 μm) reduces sanding time.- Available in rigid or flexible variants. | Excellent (no reaction with silicone). Use a light release agent (huile de silicone) pour un démoulage facile. | Rapid prototyping of intricate parts: jewelry patterns, electronic connector prototypes, and TV interface panels. |
| CNC-Machined Metals (Aluminium / laiton) | – Ultra-durable (reusable for 100+ mold makings).- High surface finish (Ra 0.4–0.8μm) for mirror-like replicas.- Résistant à la chaleur (suitable for high-temperature silicone). | Bien. Use petroleum jelly or specialized metal release spray to prevent silicone sticking. | Industrial-grade masters: automotive part prototypes (boîtiers d'équipement), mold inserts for repeated use, and high-wear components. |
| CNC-Machined Resins/Wax | – Lower cost than metal.- Facile à machine (faster turnaround than metal).- Wax is ideal for low-temperature casting (melts away if needed). | Très bien. Wax requires petroleum jelly (l'alcool dissout la cire); resin uses standard release agents. | Art prototypes: sculptural replicas, custom candle molds, and low-volume decorative parts (Par exemple, ceramic vase masters). |
| Existing Finished Parts | – No need to design a new prototype (gagner du temps).- Must be clean and undamaged (scratches transfer to the mold). | Depends on the part material: plastic/metal works; rubber may react with condensation silicone. | Reverse-engineering projects: copying legacy parts (old TV knobs), replacement components for out-of-production equipment, and competitor product analysis. |
3. Auxiliary Materials: Ensure Process Smoothness & Mold Performance
These materials enhance mold durability, prevent defects, and optimize casting results—they’re often overlooked but critical for success.
| Auxiliary Material | But | Conseils d'utilisation |
| Agents de libération de moisissure | Create a barrier between silicone and the prototype/replica to avoid sticking. | – Petroleum Jelly: Pour les prototypes en cire (faible coût, facile à appliquer).- Silicone Oil (100–500 cSt): For plastic/metal prototypes (no residue, won’t blur details).- Specialized Spray: For silicone-on-silicone casting (prevents chemical bonding).- Appliquer un mince, even layer—thick coats distort details. |
| Matériaux de renforcement | Boost mold strength and wear resistance (prevents tearing during demolding). | – Fiberglass Cloth: Lay 1–2 layers over the silicone surface (after pouring, before curing) for large molds (Par exemple, Moules de couverture arrière de téléviseur).- Silicone Fillers (Silica Powder): Mix 5–10% into silicone to increase hardness (Shore A +5–10) pour les pièces à haute teneur. |
| Curing Agents/Catalysts | Control silicone curing speed and final properties. | – Condensation Catalysts: Use 2–5% (more = faster cure, but may reduce flexibility).- Platinum Catalysts: 1:1 rapport (fixed—cannot adjust cure speed without changing temperature).- Store in cool, dry places (heat deactivates platinum catalysts). |
| Sealants/Tapes | Prevent silicone leakage from the mold frame during pouring. | – Acrylic Sealant: For permanent frame seals (wood/metal frames).- Masking Tape: For temporary seals (plastic frames, easy to remove).- Apply 2–3 layers along frame edges to fill gaps. |
4. Matériaux de coulée: The “Replica” Materials
After the silicone mold is made, these materials are poured (sous vide) pour créer la partie finale. They’re chosen based on strength, flexibilité, and end-use.
| Casting Material | Propriétés clés | Vacuum Casting Parameters | Applications |
| Polyuréthane (Puan) Résine | – Durcissement rapide (1–2 hours at 20°C–25°C; 30 minutes à 60 ° C).- Faible coût ($20–40 per kg).- Polyvalent: rigide (Shore D 60–80) ou flexible (Shore A 30–50).- Bonne résistance à l'impact (10-14 kJ / le). | – Pression de vide: -0.095 à -0.1MPA (Supprime les bulles).- Température de coulée: 25°C–30°C (too hot = flash curing). | Small-batch functional parts: Boutons de la télécommande du téléviseur, phone case replicas, and toy components. |
| Résine époxy | – Forte résistance (résistance à la traction: 50–80 MPa, contre. PU’s 30–50 MPa).- Résistant à la chaleur (120°C–180°C after curing).- Faible retrait (0.5–1%)—good for structural parts. | – Pression de vide: -0.1MPA (hold for 2–3 minutes to remove deep bubbles).- Temps de durcissement: 4–6 heures (20°C–25°C; 1–2 hours at 80°C). | Composants structurels: supports automobiles, boîtiers d'appareils électroniques (laptop bases), and medical tool handles. |
| Low-Melting Alloys (Tin-Lead/Bismuth) | – Point de fusion: 183°C–250°C (compatible with high-temperature silicone).- Finition métallique (Aucune peinture nécessaire).- Densité élevée (feels like real metal). | – Pression de vide: -0.1MPA (critical—metal bubbles cause cracks).- Température de coulée: 20°C–30°C above melting point (avoids premature solidification). | Metal replicas: matériel décoratif (poignées de porte), scale model parts (miniature car bodies), and jewelry (metal pendants). |
| Gypsum/Plaster | – Coût ultra-bas ($5–10 per kg).- Easy to color (mix pigments before pouring).- Fragile (low impact resistance—not for functional parts). | – Pression de vide: -0.08 à -0.09MPA (too high = sucks out fine particles).- Temps de durcissement: 24–48 heures (air-dry; no oven needed). | Art/teaching models: sculptural replicas, modèles anatomiques (skull casts), and classroom demonstrations. |
5. Yigu Technology’s Perspective on Silicone Vacuum Casting Materials
À la technologie Yigu, we’ve found that material mismatches cause 70% of vacuum casting failures—e.g., using condensation silicone for high-precision TV prototypes or low-temperature silicone for metal casting. Our key advice is: prioritize silicone type based on precision and end-use. For clients making electronic device shells (Par exemple, smartwatch casings), we always recommend additive silicone—it eliminates shrinkage-related defects, économie 30% en frais de reprise. For budget-sensitive projects (Par exemple, répliques artisanales), condensation silicone works but requires extra sanding to fix detail blurring. We also emphasize testing material compatibility: a client once used a rubber prototype with condensation silicone, causing the rubber to degrade—switching to a 3D-printed resin prototype solved the issue. Enfin, don’t skip reinforcement for large molds: fiberglass-clad silicone molds last 2x longer than unreinforced ones, critical for small-batch production (50+ répliques).
6. FAQ: Common Questions About Silicone Vacuum Casting Materials
T1: Can I use condensation silicone for high-precision parts (Par exemple, electronic connectors with 0.1mm slots)?
A1: No—condensation silicone’s 2–3% shrinkage will close 0.1mm slots or blur fine details. Use additive silicone instead (0.1–0.5% shrinkage) to retain precision. Par exemple, a 0.1mm slot cast with additive silicone will remain 0.095–0.1mm, while condensation silicone will reduce it to 0.07–0.08mm (too small for connectors).
T2: What casting material should I use for a functional TV remote prototype that needs to withstand drops?
A2: Use rigid polyurethane (Puan) résine (Shore D 70–80) or epoxy resin. PU resin offers better impact resistance (15 kJ/m² vs. epoxy’s 10 KJ /), making it ideal for drop-prone parts. Test by dropping the replica from 1m onto a hard surface—PU resin should not crack, while gypsum/plaster will shatter immediately.
T3: Why does my high-temperature silicone mold still deform when casting low-melting alloy?
A3: This usually stems from two issues: (1) The silicone wasn’t fully cured (insufficient oven time at 80°C—re-cure for 2 heures supplémentaires). (2) The alloy pouring temperature is too high (exceeding the silicone’s service limit—keep it 20°C–30°C above the alloy’s melting point, not higher). Par exemple, a 200°C silicone mold will deform if poured with 300°C alloy—lower the temperature to 270°C (for a 250°C melting point alloy).