Silicone mold injection molding is an advanced manufacturing technology that uses borracha de silicone líquida (LSR) as raw material, injecting it into high-precision molds under controlled temperature and pressure to produce high-quality silicone products. Unlike traditional manual mold making, it excels in mass production, high dimensional accuracy, and stable product performance—making it a core process in medical, eletrônico, e indústrias automotivas. 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. Princípios principais & Características do material
To understand silicone mold injection molding, we first break down its working mechanism and the properties of its key raw material—liquid silicone.
UM. Princípio de trabalho central
The process follows a simple but precise 因果链 (Cadeia de causa e efeito):
- Matéria -prima derretendo: Liquid silicone (two-component: main agent + agente de cura) 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).
- Injeção de alta pressão: The injection machine pushes the softened silicone into a high-precision mold cavity (tolerance ±0.01mm) at a controlled speed (5–20mm/s) e pressão (10–50MPa).
- Cura & Vulcanization: O molde está aquecido (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.
- Desmoldagem & Acabamento: Uma vez curado, O molde é aberto, and the product is ejected. Pós-processamento (Deburrendo, aparar) remove o excesso de material, resulting in a finished part.
B. Material -chave: 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 | Low viscosity (5,000–20,000 cP) | Flows into micro-details of the mold (Por exemplo, 0.1mm-thick sealing lips) |
| Resistência ao calor | Withstands -60°C to +250°C (short-term +300°C) | Suitable for high-temperature applications (Por exemplo, automotive engine gaskets) |
| Estabilidade química | Resiste a ácidos, Alkalis, Óleos, e solventes | Ideal para dispositivos médicos (sterilized with alcohol) and electronic parts (resists coolants) |
| Elasticidade | Alongamento no intervalo >500%; Shore hardness 20–80A | Ensures products (Por exemplo, phone buttons, O-rings) maintain flexibility after repeated use |
| Biocompatibilidade | Medical-grade LSR meets FDA 21 CFR §177.2600 | Safe for skin-contact products (Por exemplo, 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.
Etapa 1: Preparação de matéria -prima & Teste
- Component Mixing: Blend LSR main agent and curing agent in a precise ratio (comum 1:1 ou 10:1) using an automated mixer. For colored products, add 1–3% non-toxic pigments to the mixture.
- Inspeção de qualidade: 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).
Etapa 2: Design de molde & Fabricação
Molds are the “heart” of the process—their precision directly impacts product quality.
- Considerações de design:
- Localização do portão: Coloque portões (injection inlets) at thick sections to avoid air traps. Para peças pequenas (Por exemplo, conectores eletrônicos), use pinpoint gates (0.5–1mm diâmetro).
- Sistema de resfriamento: Add water channels around the cavity to control mold temperature (±2°C tolerance)—prevents uneven curing.
- Tratamento de superfície: Apply chrome plating (5–10μm thickness) or nitriding to the mold surface. This improves wear resistance (extends mold life to 100,000+ ciclos) and release performance (reduces sticking).
- Manufacturing Equipment: Use CNC machining centers (accuracy ±0.005mm) to mill the mold cavity. Para formas complexas (Por exemplo, componentes de dispositivos médicos), add EDM (Usinagem de descarga elétrica) for micro-details.
Etapa 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:
| Parâmetro | Ideal Range | Impact of Incorrect Settings |
| Temperatura do barril | 40–60 ° C. (zone 1: 40° c; zone 2: 50° c; zone 3: 60° c) | Muito alto (>70° c) = premature curing (blocks the barrel); Muito baixo (<30° c) = poor flow |
| Pressão de injeção | 15–30MPa | Muito alto (>40MPA) = mold deformation; Muito baixo (<10MPA) = incomplete cavity filling |
| Injection Speed | 8–15mm/s (staged: slow start → fast middle → slow end) | Too fast (>20mm/s) = air trapping (bolhas); Muito lento (<5mm/s) = cold slugs (uneven texture) |
| Temperatura do molde | 140–160 ° C. | Muito alto (>180° c) = over-curing (peças quebradiças); Muito baixo (<120° c) = under-curing (sticky surface) |
| Tempo de cura | 10–120 segundos (1 second per mm of thickness) | Too short = under-curing; too long = reduced production efficiency |
Etapa 4: Cura, Desmoldagem & Pós-processamento
- Cura: The mold remains closed for the set time—use a mold temperature controller to maintain stable heat.
- Desmoldagem: Use robotic ejectors (para produção em massa) or manual tools (Para pequenos lotes) Para remover as peças. Apply a thin layer of silicone release agent if sticking occurs (evite o excesso - causa defeitos superficiais).
- Pós-processamento:
- Deburrendo: Apare os resíduos do portão com um cortador a laser (Para peças de precisão) ou tesoura afiada (para peças não críticas).
- Limpeza: Lave as peças com água deionizada para remover resíduos do agente desmoldante.
- Vulcanização Secundária (Opcional): Para peças de alta temperatura (Por exemplo, vedações automotivas), leve ao forno a 200°C por 2–4 horas para melhorar a resistência ao calor.
3. Vantagens & Desafios: Uma análise comparativa
A moldagem por injeção de molde de silicone tem pontos fortes claros em comparação com os métodos tradicionais de fabricação (Por exemplo, moldagem por compressão, fundição manual). Ele também enfrenta desafios únicos – compreender ambos ajuda os usuários a decidir se é o processo certo.
UM. Advantages Over Traditional Methods
| Vantagem | Moldagem por injeção de molde de silicone | Moldagem por compressão | Fundição Manual |
| Eficiência de produção | Alto (30–60 parts per minute for small components) | Médio (5–10 parts per minute) | Baixo (1–2 parts per hour) |
| Precisão dimensional | ± 0,01 mm (ideal for precision parts) | ± 0,1 mm (limited by mold pressure) | ± 0,5 mm (human error) |
| Product Consistency | 99.5% uniformidade (processo automatizado) | 90% uniformidade (Depende da habilidade do operador) | 70% uniformidade (high variability) |
| Manipulação de complexidade | Excelente (can produce parts with undercuts, Micro-Holes) | Pobre (requires split molds for complexity) | Muito pobre (limited to simple shapes) |
| Desperdício de material | Baixo (<5% scrap—excess can be recycled) | Médio (10–15% scrap) | Alto (20–30% scrap) |
B. Principais desafios & Mitigation Strategies
| Desafio | Causa raiz | Mitigation Strategy |
| High Initial Investment | Mold manufacturing (Usinagem CNC + tratamento de superfície) custos \(10,000- )100,000; injection machines cost \(50,000- )200,000 | – Para pequenos lotes: Use shared molds (reduces cost by 50%).- For long-term projects: Choose high-wear-resistant mold materials (Por exemplo, Aço H13) to extend life (100,000+ ciclos) |
| 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) |
| Defeitos de encolhimento | Uneven cooling or over-curing | – Optimize mold cooling channels (ensure uniform temperature).- Add 1–2% shrinkage allowance to the mold design |
4. Application Fields: Onde brilha
Silicone mold injection molding is widely used in industries that demand precision, durabilidade, e biocompatibilidade. The table below highlights key applications with specific examples:
| Indústria | Typical Products | LSR Grade | Key Process Requirements |
| Dispositivos médicos | Dicas de cateter, surgical instrument gaskets, baby pacifiers | Medical-grade (FDA 21 CFR §177.2600) | – Cleanroom production (Aula 100,000).- No release agent (avoids contamination).- Biocompatibility testing post-production |
| Eletrônica | Phone buttons, LED lamp seals, sensor O-rings | Industrial (high insulation) | – Alta precisão (±0.005mm for button travel).- Low volatility (no VOCs to damage electronics) |
| Automotivo | Engine gaskets, fuel system seals, Componentes do painel | High-temperature grade (resists 250°C) | – Resistência química (para óleos, Coolentes).- Vibration resistance (alongamento >500%) |
| Bens de consumo | Silicone kitchen utensils (spatulas), waterproof watch bands | Food-grade (Aprovado pela FDA) | – Non-toxic pigments.- Superfície lisa (Rá <0.8μm) Para uma limpeza fácil |
5. Yigu Technology’s Perspective on Silicone Mold Injection Molding
Na tecnologia Yigu, we see silicone mold injection molding as a cornerstone of high-precision manufacturing—especially for industries like medical and automotive. Para clientes médicos, our custom injection molds (tolerância ± 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 (Por exemplo, coated aluminum) that cut mold costs by 40% enquanto mantém 50,000+ ciclos; 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.
Perguntas frequentes
- Qual é a quantidade mínima de pedido (MOQ) for silicone mold injection molding?
MOQ depends on mold cost: Para peças padrão (Por exemplo, O-rings), MOQ is 10,000–50,000 units (para compensar os custos de molde). Para peças personalizadas, we offer shared molds with MOQ as low as 1,000 unidades (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 (Rá <0.02μm). We’ve produced transparent medical connectors with 90% Transmitância de luz, 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 (Usinagem CNC + teste). After mold approval, production can start within 1 semana. Para projetos urgentes (Por exemplo, medical device emergencies), we offer expedited mold development (2–3 semanas) with priority production.