Silicone mold injection molding is an advanced manufacturing technology that uses liquid silicone rubber (LSR) come materia prima, iniettandolo in stampi ad alta precisione a temperatura e pressione controllate per produrre prodotti in silicone di alta qualità. A differenza della tradizionale realizzazione manuale di stampi, eccelle nella produzione di massa, elevata precisione dimensionale, and stable product performance—making it a core process in medical, elettronico, e industrie automobilistiche. But what are its core principles? How to control key processes? And how to address its unique challenges? This article answers these questions in detail.
1. Core Principles & Material Characteristics
To understand silicone mold injection molding, we first break down its working mechanism and the properties of its key raw material—liquid silicone.
UN. Core Working Principle
The process follows a simple but precise 因果链 (cause-and-effect chain):
- Raw Material Melting: Liquid silicone (two-component: main agent + curing agent) is fed into the injection machine’s barrel, where it is heated to a flowable state (no melting—silicone is thermoset, so this step softens it for injection).
- High-Pressure Injection: The injection machine pushes the softened silicone into a high-precision mold cavity (tolerance ±0.01mm) at a controlled speed (5–20mm/s) e pressione (10–50MPa).
- Curare & Vulcanization: Lo stampo viene riscaldato (120–180°C) to trigger a chemical reaction in the silicone, turning it from liquid to elastic solid. Curing time depends on product thickness—e.g., 1mm-thick parts take 10–15 seconds; 10mm-thick parts take 60–90 seconds.
- Sformatura & Finitura: Una volta guarito, lo stampo si apre, and the product is ejected. Post-elaborazione (sbavatura, rifilatura) removes excess material, resulting in a finished part.
B. Materiale chiave: Liquid Silicone Rubber (LSR)
LSR’s unique properties determine the process’s advantages. The table below highlights its critical characteristics:
| Material Characteristic | Specific Performance | Role in Injection Molding |
| Fluidity | Bassa viscosità (5,000–20,000 cP) | Flows into micro-details of the mold (per esempio., 0.1mm-thick sealing lips) |
| Resistenza al calore | Withstands -60°C to +250°C (short-term +300°C) | Suitable for high-temperature applications (per esempio., automotive engine gaskets) |
| Chemical Stability | Resiste agli acidi, alcali, oli, e solventi | Ideale per dispositivi medici (sterilized with alcohol) and electronic parts (resists coolants) |
| Elasticità | Elongation at break >500%; Shore hardness 20–80A | Ensures products (per esempio., phone buttons, O-ring) maintain flexibility after repeated use |
| Biocompatibilità | Medical-grade LSR meets FDA 21 CFR §177.2600 | Safe for skin-contact products (per esempio., baby pacifiers, medical catheters) |
2. Step-by-Step Production Process
Silicone mold injection molding follows a standardized, linear workflow—each step requires strict parameter control to avoid defects.
Fare un passo 1: Raw Material Preparation & Test
- Component Mixing: Blend LSR main agent and curing agent in a precise ratio (common 1:1 O 10:1) using an automated mixer. For colored products, add 1–3% non-toxic pigments to the mixture.
- Ispezione di qualità: Conduct 3 key tests:
- Viscosity Test: Ensure viscosity is 5,000–15,000 cP (too high = poor flow; too low = leakage).
- Curing Test: Cure a small sample at 160°C for 30 seconds—check for full solidification (no sticky surface).
- Impurity Check: Filter the mixture through a 5μm sieve to remove particles (prevents mold clogging).
Fare un passo 2: Progettazione di stampi & Produzione
Molds are the “heart” of the process—their precision directly impacts product quality.
- Design Considerations:
- Gate Location: Place gates (injection inlets) at thick sections to avoid air traps. Per piccole parti (per esempio., connettori elettronici), use pinpoint gates (0.5–1mm diameter).
- Sistema di raffreddamento: Add water channels around the cavity to control mold temperature (±2°C tolerance)—prevents uneven curing.
- Trattamento superficiale: Apply chrome plating (5–10μm thickness) or nitriding to the mold surface. This improves wear resistance (extends mold life to 100,000+ cicli) and release performance (reduces sticking).
- Manufacturing Equipment: Use CNC machining centers (accuracy ±0.005mm) to mill the mold cavity. For complex shapes (per esempio., componenti di dispositivi medici), add EDM (Lavorazione ad elettroerosione) for micro-details.
Fare un passo 3: Injection Molding Parameter Setup
Key parameters must be optimized—incorrect settings cause defects like bubbles or shrinkage. The table below lists critical parameters and their ideal ranges:
| Parametro | Ideal Range | Impact of Incorrect Settings |
| Temperatura della canna | 40–60°C (zone 1: 40°C; zone 2: 50°C; zone 3: 60°C) | Too high (>70°C) = premature curing (blocks the barrel); troppo basso (<30°C) = poor flow |
| Pressione di iniezione | 15–30MPa | Too high (>40MPa) = mold deformation; troppo basso (<10MPa) = incomplete cavity filling |
| Velocità di iniezione | 8–15mm/s (staged: slow start → fast middle → slow end) | Too fast (>20mm/s) = air trapping (bolle); troppo lento (<5mm/s) = cold slugs (uneven texture) |
| Temperatura dello stampo | 140–160°C | Too high (>180°C) = over-curing (brittle parts); troppo basso (<120°C) = under-curing (sticky surface) |
| Tempo di polimerizzazione | 10–120 secondi (1 second per mm of thickness) | Too short = under-curing; too long = reduced production efficiency |
Fare un passo 4: Curare, Sformatura & Post-elaborazione
- Curare: The mold remains closed for the set time—use a mold temperature controller to maintain stable heat.
- Sformatura: Use robotic ejectors (per la produzione di massa) o strumenti manuali (per piccoli lotti) to remove parts. Apply a thin layer of silicone release agent if sticking occurs (avoid excess—causes surface defects).
- Post-elaborazione:
- Sbavatura: Trim gate residues with a laser cutter (for precision parts) or sharp scissors (per le parti non critiche).
- Pulizia: Wash parts with deionized water to remove release agent residue.
- Secondary Vulcanization (Opzionale): For high-temperature parts (per esempio., guarnizioni automobilistiche), bake at 200°C for 2–4 hours to improve heat resistance.
3. Vantaggi & Sfide: A Comparative Analysis
Silicone mold injection molding has clear strengths compared to traditional manufacturing methods (per esempio., stampaggio a compressione, manual casting). It also faces unique challenges—understanding both helps users decide if it’s the right process.
UN. Advantages Over Traditional Methods
| Vantaggio | Silicone Mold Injection Molding | Stampaggio a compressione | Manual Casting |
| Production Efficiency | Alto (30–60 parts per minute for small components) | Medio (5–10 parts per minute) | Basso (1–2 parts per hour) |
| Precisione dimensionale | ±0,01 mm (ideal for precision parts) | ±0,1 mm (limited by mold pressure) | ±0,5 mm (human error) |
| Product Consistency | 99.5% uniformity (processo automatizzato) | 90% uniformity (dipende dall'abilità dell'operatore) | 70% uniformity (high variability) |
| Gestione della complessità | Eccellente (can produce parts with undercuts, microfori) | Povero (requires split molds for complexity) | Very poor (limited to simple shapes) |
| Rifiuti materiali | Basso (<5% scrap—excess can be recycled) | Medio (10–15% scrap) | Alto (20–30% scrap) |
B. Key Challenges & Mitigation Strategies
| Sfida | Root Cause | Mitigation Strategy |
| High Initial Investment | Mold manufacturing (Lavorazione CNC + trattamento superficiale) costi \(10,000–)100,000; injection machines cost \(50,000–)200,000 | – Per piccoli lotti: Use shared molds (reduces cost by 50%).- For long-term projects: Choose high-wear-resistant mold materials (per esempio., Acciaio H13) to extend life (100,000+ cicli) |
| Mold Clogging | Impurities in LSR or low fluidity | – Filter LSR through 5μm sieves before injection.- Preheat LSR to 50°C (improves fluidity) |
| Bubble Formation | Air trapped during injection or incomplete venting | – Add vent grooves (0.01–0.02mm depth) to the mold.- Use vacuum-assisted injection (removes air from the cavity) |
| Shrinkage Defects | Uneven cooling or over-curing | – Optimize mold cooling channels (ensure uniform temperature).- Add 1–2% shrinkage allowance to the mold design |
4. Application Fields: Where It Shines
Silicone mold injection molding is widely used in industries that demand precision, durabilità, e biocompatibilità. The table below highlights key applications with specific examples:
| Industria | Typical Products | LSR Grade | Key Process Requirements |
| Dispositivi medici | Consigli per i cateteri, surgical instrument gaskets, baby pacifiers | Di livello medico (FDA 21 CFR §177.2600) | – Cleanroom production (Classe 100,000).- No release agent (avoids contamination).- Biocompatibility testing post-production |
| Elettronica | Phone buttons, LED lamp seals, sensor O-rings | Di livello industriale (high insulation) | – Alta precisione (±0.005mm for button travel).- Low volatility (no VOCs to damage electronics) |
| Automobilistico | Engine gaskets, fuel system seals, componenti del cruscotto | High-temperature grade (resists 250°C) | – Resistenza chimica (agli oli, coolants).- Vibration resistance (allungamento >500%) |
| Beni di consumo | Silicone kitchen utensils (spatulas), waterproof watch bands | Food-grade (Approvato dalla FDA) | – Non-toxic pigments.- Superficie liscia (Ra <0.8µm) per una facile pulizia |
5. Yigu Technology’s Perspective on Silicone Mold Injection Molding
Alla tecnologia Yigu, we see silicone mold injection molding as a cornerstone of high-precision manufacturing—especially for industries like medical and automotive. Per clienti medici, our custom injection molds (tolleranza ±0,008 mm) and medical-grade LSR have enabled the production of 100,000+ catheter tips with 0% biocompatibility failures. For automotive partners, our high-temperature LSR (resists 280°C) and optimized cooling systems reduce engine gasket shrinkage to <0.5%, improving product lifespan by 30%.
We’re addressing key challenges by: 1) Developing low-cost mold materials (per esempio., coated aluminum) that cut mold costs by 40% pur mantenendo 50,000+ cicli; 2) Integrating AI into parameter control (automatically adjusts temperature/pressure to reduce defects by 25%). Our goal is to make this technology accessible to mid-sized businesses—balancing precision with affordability.
Domande frequenti
- Qual è la quantità minima dell'ordine (MOQ) for silicone mold injection molding?
MOQ depends on mold cost: Per parti standard (per esempio., O-ring), MOQ is 10,000–50,000 units (to offset mold costs). Per parti personalizzate, we offer shared molds with MOQ as low as 1,000 unità (ideal for small-batch testing).
- Can silicone mold injection molding produce transparent silicone products?
Yes—use high-purity LSR (impurity content <0.1%) and polished molds (Ra <0.02µm). We’ve produced transparent medical connectors with 90% trasmissione della luce, meeting optical requirements for device visualization.
- How long does it take to develop a custom silicone mold and start production?
Mold development takes 4–6 weeks (Lavorazione CNC + test). After mold approval, production can start within 1 settimana. Per progetti urgenti (per esempio., medical device emergencies), we offer expedited mold development (2–3 settimane) with priority production.