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, flessibilità, and detail replication, making it ideal for small-batch production and product development. Questo articolo analizza le sue definizioni principali, flusso di lavoro passo dopo passo, selezioni dei materiali, Vantaggi, and limitations—with clear comparisons and real-world examples to help you optimize the process for your projects.
1. Definizione principale & Principi chiave
Prima di immergersi nel processo, it’s critical to understand what makes plastic compound mold processing unique and how it differs from traditional methods.
| Aspetto | Plastic Compound Mold Processing | Traditional Steel Injection Molding |
| Materiale della muffa | Primarily silicone rubber (flessibile, elastico, and detail-retaining). | Rigid materials like acciaio O alluminio (highly durable but costly to machine). |
| Principio fondamentale | 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) per la produzione di massa. |
| Batch Suitability | Ideale per piccoli lotti (10–500 unità) e prototipazione. | Designed for mass production (10,000+ unità) to offset high mold costs. |
| Vantaggio chiave | Low mold cost, rapido inversione di tendenza, and ability to replicate complex shapes/textures. | Elevata efficienza di produzione, superior part accuracy, and long mold life (100,000+ cicli). |
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 Palcoscenico 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.
| Prototype Manufacturing Method | Caratteristiche chiave | Ideale per |
| 3D Stampa (SLA/DLP) | – Alta precisione (± 0,05 mm) for intricate details (PER ESEMPIO., Loghi, trame).- Finitura superficiale liscia (RA 0,8–1,6 μm) reduces post-processing.- Rapido inversione di tendenza (12–24 hours for small parts). | Parti complesse: gusci di dispositivi elettronici (custodie telefoniche, Involucri per telecomandi TV), decorative items with fine patterns. |
| MACCHING CNC | – Ultra-high accuracy (± 0,01 mm) for tight tolerances.- Suitable for hard materials (metallo, plastica rigida, legna).- Ideal for flat or geometrically precise parts. | Componenti di alta precisione: staffe automobilistiche, Alloggi per dispositivi medici, parts requiring strict dimensional consistency. |
| Hand Engraving/Crafting | – Low cost for simple shapes.- Flexible for one-of-a-kind designs.- Non sono necessarie attrezzature specializzate. | Simple decorative parts: custom keychains, small figurines, low-precision prototypes for visual testing. |
Suggerimento critico: Ensure the prototype is clean and defect-free (no dust, olio, o graffi). 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 Palcoscenico 2: Produzione di stampi in silicone (The “Negative Template”)
This stage transforms the prototype into a reusable mold. Proper silicone mixing, versare, and curing are essential to avoid bubbles, lacrime, or incomplete detail capture.
Fare un passo 1: Mold Frame Setup
- Frame Selection: Choose a frame material (legna, plastica, o metallo) large enough to fit the prototype with 5–10mm of space on all sides (ensures even silicone coverage).
- Sigillatura: 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.
Fare un passo 2: Silicone Mixing
- Selezione del materiale: Use two-component silicone rubber (Parte A.: base; Part B: agente curativo) with a mixing ratio specified by the manufacturer (in genere 1:1 by volume/weight for additive silicone, 10:1 for condensation silicone).
- Mixing Rules:
- Stir slowly and thoroughly (2–3 minuti) to avoid air bubbles—uneven mixing causes weak spots in the mold.
- Per grandi lotti, Usa un vacuum degassing machine (1–2 minutes at -0.1MPA) to remove trapped air—critical for parts with tiny details (PER ESEMPIO., 0.5fessure larghe mm).
Fare un passo 3: Silicone Pouring & Polimerizzazione
- Tecnica di versamento: Tilt the frame at a 45° angle and pour silicone slowly along the frame wall (non direttamente sul prototipo)—reduces bubble formation. For thick molds (>10mm), utilizzo layered pouring: versare 1/3 of the silicone, Aspettare 30 minutes for bubbles to rise, then add the next layer.
- Curing Parameters:
| Tipo di silicone | Temperatura di cura | Tempo di cura (for 5mm Thickness) | Post-Curing Tip |
| Additivo (Platinum-Cure) | 20°C–25°C | 2–4 ore | No post-curing needed; ready to demold once firm. |
| Condensation | 20°C–25°C | 4–8 ore | Cure for an extra 1 hour if mold is thicker than 10mm. |
| Resistente alle alte temperature | 20°C–25°C (iniziale); 80° C. (post) | 6–10 ore (iniziale); 2 ore (post) | Post-cure in an oven to activate heat resistance (fino a 200 ° C.). |
Fare un passo 4: Demolding the Prototype
- Una volta curato, gently peel the silicone mold from the prototype—silicone’s elasticity ensures easy removal without damaging either the mold or prototype.
- Trim excess silicone (flash) from mold edges with a sharp knife—creates a clean, precise mold for plastic casting.
2.3 Palcoscenico 3: Plastic Part Production (The “Replica Process”)
Con lo stampo in silicone pronto, this stage produces finished plastic parts through pouring, polimerizzazione, and demolding.
Fare un passo 1: Plastic Material Selection
Choose a material based on the part’s end-use (forza, flessibilità, Resistenza al calore):
| Materiale plastico | Proprietà chiave | Applicazioni ideali |
| Poliuretano (Pu) Resina | – Currezione rapida (1–2 hours at 20°C).- Good wear resistance and flexibility (Shore A 30–80).- Basso costo ($20–40 per kg). | Parti funzionali: TV remote buttons, componenti giocattoli, flexible gaskets, small electronic housings. |
| Resina epossidica | – Alta resistenza (resistenza alla trazione: 50–80 MPa) and chemical resistance.- Resistente al calore (120°C–180°C after curing).- Basso restringimento (0.5–1%). | Parti strutturali: Assesso interno automobilistico, maniglie dei dispositivi medici, parts requiring durability under stress. |
| Polivinil cloruro (PVC) | – Low cost and good chemical stability.- Rigid or flexible variants available.- Suitable for food-contact parts (when food-grade). | Custom containers, rivestimento decorativo, low-stress household items. |
Fare un passo 2: Versare & Polimerizzazione
- Versare: Pour liquid plastic into the silicone mold slowly (use a small funnel for narrow openings) to avoid bubbles. For complex parts with internal cavities, utilizzo sectional pouring: fill one section, Aspettare 10 minutes for partial curing, then fill the next—ensures full cavity coverage.
- Polimerizzazione:
- Room-temperature curing: Resina PU (1–2 ore), resina epossidica (4–6 ore).
- Accelerated curing: Use a low-temperature oven (50°C–60°C) to reduce time by 50% (PER ESEMPIO., epoxy resin cures in 2–3 hours).
Fare un passo 3: Sformatura & Post-elaborazione
- Gently peel the silicone mold from the plastic part—silicone’s flexibility prevents cracking or deformation.
- Trim excess plastic (flash) 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:
| Categoria di vantaggio | Vantaggi chiave | Esempio nel mondo reale |
| Basso costo | – Silicone mold cost is 50–70% lower than steel molds (PER ESEMPIO., \(200 contro. \)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. |
| Rapido inversione di tendenza | – Entire process (prototype → mold → parts) takes 3–7 days, contro. 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 giorni, enabling faster design iterations. |
| Complex Detail Replication | – Captures tiny textures (0.1mm - 0,5 mm), superfici curve, 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. |
| Flessibilità | – Easy to adjust mold design (PER ESEMPIO., 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 colori (nero, bianco, blu) using the same silicone mold—no need for multiple molds, cutting color-testing costs by 60%. |
4. Limitazioni da considerare
While highly effective for specific use cases, plastic compound mold processing has constraints:
- Limited Mold Life: Silicone molds last 20–500 cicli (contro. 100,000+ for steel molds). Parts with sharp edges or high friction (PER ESEMPIO., Clip di plastica) wear down molds faster—after 50 cicli, a mold may start to lose detail.
- Lower Part Accuracy: Dimensional accuracy is ±0.1mm–±0.3mm (contro. ±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 (contro. 100+ parts per hour for steel injection molding). For batches over 500 unità, it becomes slower and more costly than traditional methods.
5. Yigu Technology’s Perspective on Plastic Compound Mold Processing
Alla tecnologia 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 cicli. We advised switching to steel molds for mass production, salvandoli 40% nei costi di rielaborazione. Per prototipazione, we recommend additive silicone (1:1 rapporto) 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. Domande frequenti: Common Questions About Plastic Compound Mold Processing
Q1: Can I use plastic compound mold processing for high-temperature parts (PER ESEMPIO., parts exposed to 150°C)?
A1: SÌ, but use heat-resistant materials. Scegliere high-temperature silicone (temperatura di servizio: 200° C - 300 ° C.) for the mold and heat-resistant epoxy resin (cured temp: 120°C–180°C) per la parte. Test a sample first—expose it to 150°C for 24 hours to ensure no deformation. Avoid standard silicone (Max temp: 150° C.) or PU resin (Max temp: 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).- Applicare un sottile strato di olio siliconico sullo stampo prima di versare la plastica: riduce l'attrito e l'usura.- Conserva lo stampo in una fresca, luogo asciutto (umidità <60%) and avoid folding or stretching it—prevents tears.
Q3: Are parts made via plastic compound mold processing suitable for food contact?
A3: Solo se utilizzi materiali per uso alimentare. Scegliere food-safe silicone (certified by FDA or EU standards) for the mold and food-grade plastic resins (PER ESEMPIO., PU per uso alimentare, PVC, or epoxy). Regular materials may leach chemicals into food—always test the final part for compliance (PER ESEMPIO., FDA 21 Cfr 177.2600 per resina) prima dell'uso.