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, flexibilité, and detail replication, making it ideal for small-batch production and product development. Cet article décompose ses définitions principales, flux de travail étape par étape, sélections de matériaux, avantages, and limitations—with clear comparisons and real-world examples to help you optimize the process for your projects.
1. Définition de base & Principes clés
Avant de plonger dans le processus, it’s critical to understand what makes plastic compound mold processing unique and how it differs from traditional methods.
| Aspect | Plastic Compound Mold Processing | Traditional Steel Injection Molding |
| Matériau de moule | Primarily silicone rubber (flexible, élastique, et conservation des détails). | Des matériaux rigides comme acier ou aluminium (très durable mais coûteux à usiner). |
| Principe de base | Reproduit les pièces en versant du plastique liquide dans un moule en silicone (créé à partir d'un prototype), puis durcissement et démoulage. | Injecte du plastique fondu dans un moule en acier sous haute pression (10–150 MPA) pour la production de masse. |
| Adéquation des lots | Idéal pour les petits lots (10–500 unités) et prototypage. | Conçu pour la production de masse (10,000+ unités) pour compenser les coûts élevés du moule. |
| Avantage clé | Faible coût du moule, revirement rapide, et capacité à reproduire des formes/textures complexes. | Efficacité de production élevée, précision supérieure des pièces, et longue durée de vie du moule (100,000+ cycles). |
Question clé: Pourquoi choisir le traitement des moules composés de plastique?
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 Scène 1: Préparation des prototypes (The “Master Model”)
The prototype serves as the template for the silicone mold—its quality determines the detail and accuracy of all subsequent parts.
| Méthode de fabrication des prototypes | Caractéristiques clés | Idéal pour |
| 3D Impression (SLA/DLP) | – Haute précision (± 0,05 mm) for intricate details (Par exemple, logos, textures).- Finition de surface lisse (RA 0,8–1,6 μm) reduces post-processing.- Revirement rapide (12–24 hours for small parts). | Parties complexes: Shels de dispositif électronique (caisses téléphoniques, TV remote casings), decorative items with fine patterns. |
| Usinage CNC | – Ultra-high accuracy (± 0,01 mm) for tight tolerances.- Suitable for hard materials (métal, plastique rigide, bois).- Ideal for flat or geometrically precise parts. | High-precision components: supports automobiles, boîtiers de dispositifs médicaux, 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. |
Conseil critique: Ensure the prototype is clean and defect-free (no dust, huile, ou rayures). 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 Scène 2: Fabrication de moisissures en silicone (The “Negative Template”)
This stage transforms the prototype into a reusable mold. Proper silicone mixing, coulant, and curing are essential to avoid bubbles, larmes, or incomplete detail capture.
Étape 1: Configuration du cadre de moule
- Frame Selection: Choose a frame material (bois, plastique, ou métal) large enough to fit the prototype with 5–10mm of space on all sides (ensures even silicone coverage).
- Scellage: 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.
Étape 2: Mélange de silicone
- Sélection des matériaux: Use two-component silicone rubber (Partie A: base; Part B: agent de durcissement) with a mixing ratio specified by the manufacturer (typiquement 1:1 en volume/poids for additive silicone, 10:1 for condensation silicone).
- Mixing Rules:
- Stir slowly and thoroughly (2–3 minutes) to avoid air bubbles—uneven mixing causes weak spots in the mold.
- Pour les grands lots, Utiliser un vacuum degassing machine (1–2 minutes à -0.1MPA) to remove trapped air—critical for parts with tiny details (Par exemple, 0.5fentes de mm de large).
Étape 3: Coulée de silicone & Durcissement
- Technique de versement: Tilt the frame at a 45° angle and pour silicone slowly along the frame wall (pas directement sur le prototype)—reduces bubble formation. Pour moules épais (>10mm), utiliser layered pouring: verser 1/3 of the silicone, attendez 30 minutes for bubbles to rise, then add the next layer.
- Curing Parameters:
| Type en silicone | Température de durcissement | Temps de durcissement (for 5mm Thickness) | Post-Curing Tip |
| Additif (Platinum-Cure) | 20°C–25°C | 2–4 heures | No post-curing needed; ready to demold once firm. |
| Condensation | 20°C–25°C | 4–8 heures | Cure for an extra 1 hour if mold is thicker than 10mm. |
| Résistant aux hautes températures | 20°C–25°C (initial); 80° C (post) | 6–10 heures (initial); 2 heures (post) | Post-cure in an oven to activate heat resistance (jusqu'à 200 ° C). |
Étape 4: Demolding the Prototype
- Une fois guéri, gently peel the silicone mold from the prototype—silicone’s elasticity ensures easy removal without damaging either the mold or prototype.
- Trim excess silicone (éclair) from mold edges with a sharp knife—creates a clean, precise mold for plastic casting.
2.3 Scène 3: Plastic Part Production (The “Replica Process”)
Avec le moule en silicone prêt, this stage produces finished plastic parts through pouring, durcissement, and demolding.
Étape 1: Plastic Material Selection
Choose a material based on the part’s end-use (force, flexibilité, résistance à la chaleur):
| Matériaux plastiques | Propriétés clés | Applications idéales |
| Polyuréthane (Puan) Résine | – Durcissement rapide (1–2 hours at 20°C).- Good wear resistance and flexibility (Shore A 30–80).- Faible coût ($20–40 per kg). | Parties fonctionnelles: Boutons de la télécommande du téléviseur, composants jouets, flexible gaskets, small electronic housings. |
| Résine époxy | – Forte résistance (résistance à la traction: 50–80 MPa) and chemical resistance.- Résistant à la chaleur (120°C–180°C after curing).- Faible retrait (0.5–1%). | Parties structurelles: garniture intérieure automobile, Poignées des dispositifs médicaux, parts requiring durability under stress. |
| Chlorure de polyvinyle (PVC) | – Low cost and good chemical stability.- Rigid or flexible variants available.- Suitable for food-contact parts (when food-grade). | Custom containers, garniture décorative, low-stress household items. |
Étape 2: Coulant & Durcissement
- Coulant: Pour liquid plastic into the silicone mold slowly (use a small funnel for narrow openings) pour éviter les bulles. For complex parts with internal cavities, utiliser sectional pouring: fill one section, attendez 10 minutes for partial curing, then fill the next—ensures full cavity coverage.
- Durcissement:
- Durcissement à température ambiante: Résine PU (1–2 heures), résine époxy (4–6 heures).
- Durcissement accéléré: Use a low-temperature oven (50°C–60°C) to reduce time by 50% (Par exemple, epoxy resin cures in 2–3 hours).
Étape 3: Démêlé & Post-traitement
- Gently peel the silicone mold from the plastic part—silicone’s flexibility prevents cracking or deformation.
- Trim excess plastic (éclair) 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:
| Catégorie d'avantage | Avantages clés | Exemple du monde réel |
| Faible coût | – Silicone mold cost is 50–70% lower than steel molds (Par exemple, \(200 contre. \)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. |
| Revirement rapide | – Entire process (prototype → mold → parts) takes 3–7 days, contre. 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 jours, enabling faster design iterations. |
| Complex Detail Replication | – Captures tiny textures (0.1mm - 0,5 mm), surfaces courbes, 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. |
| Flexibilité | – Easy to adjust mold design (Par exemple, 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 couleurs (noir, blanc, bleu) using the same silicone mold—no need for multiple molds, cutting color-testing costs by 60%. |
4. Limitations à considérer
While highly effective for specific use cases, plastic compound mold processing has constraints:
- Limited Mold Life: Silicone molds last 20–500 cycles (contre. 100,000+ for steel molds). Parts with sharp edges or high friction (Par exemple, clips plastiques) wear down molds faster—after 50 cycles, a mold may start to lose detail.
- Lower Part Accuracy: Dimensional accuracy is ±0.1mm–±0.3mm (contre. ±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 (contre. 100+ parts per hour for steel injection molding). Pour les lots supérieurs 500 unités, it becomes slower and more costly than traditional methods.
5. Yigu Technology’s Perspective on Plastic Compound Mold Processing
À la technologie 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 cycles. We advised switching to steel molds for mass production, les sauver 40% en frais de reprise. Pour le prototypage, we recommend additive silicone (1:1 rapport) 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. FAQ: Common Questions About Plastic Compound Mold Processing
T1: Can I use plastic compound mold processing for high-temperature parts (Par exemple, parts exposed to 150°C)?
A1: Oui, but use heat-resistant materials. Choisir high-temperature silicone (service temp: 200° C - 300 ° C) for the mold and heat-resistant epoxy resin (cured temp: 120°C–180°C) pour la part. Test a sample first—expose it to 150°C for 24 hours to ensure no deformation. Avoid standard silicone (température maximale: 150° C) or PU resin (température maximale: 80° C) for high-heat applications.
T2: 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.- Conservez le moule dans un frais, lieu sec (humidité <60%) and avoid folding or stretching it—prevents tears.
T3: Are parts made via plastic compound mold processing suitable for food contact?
A3: Only if you use food-grade materials. Choisir food-safe silicone (certified by FDA or EU standards) for the mold and food-grade plastic resins (Par exemple, food-grade PU, PVC, or epoxy). Regular materials may leach chemicals into food—always test the final part for compliance (Par exemple, FDA 21 CFR 177.2600 pour résine) avant utilisation.