Silicone mold injection molding is an advanced manufacturing technology that uses liquid silicone rubber (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, hohe Maßgenauigkeit, and stable product performance—making it a core process in medical, elektronisch, und Automobilindustrie. 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. Kernprinzipien & Materialmerkmale
To understand silicone mold injection molding, we first break down its working mechanism and the properties of its key raw material—liquid silicone.
A. Kernprinzip
The process follows a simple but precise 因果链 (Ursache-Wirkungs-Kette):
- Rohstoffschmelzen: Flüssiges Silikon (two-component: main agent + Härtungsmittel) 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).
- Hochdruckeinspritzung: The injection machine pushes the softened silicone into a high-precision mold cavity (tolerance ±0.01mm) at a controlled speed (5–20mm/s) und Druck (10–50MPa).
- Heilung & Vulcanization: Die Form ist erhitzt (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.
- Entformen & Fertig: Einmal geheilt, Die Form öffnet sich, and the product is ejected. Nachbearbeitung (Enttäuschung, Trimmen) removes excess material, resulting in a finished part.
B. Schlüsselmaterial: Liquid Silicone Rubber (LSR)
LSR’s unique properties determine the process’s advantages. The table below highlights its critical characteristics:
| Material Characteristic | Spezifische Leistung | Role in Injection Molding |
| Fluidity | Low viscosity (5,000–20,000 cP) | Flows into micro-details of the mold (Z.B., 0.1mm-thick sealing lips) |
| Wärmewiderstand | Withstands -60°C to +250°C (short-term +300°C) | Suitable for high-temperature applications (Z.B., automotive engine gaskets) |
| Chemische Stabilität | Widersteht Säuren, Alkalis, Öle, und Lösungsmittel | Ideal für Medizinprodukte (sterilized with alcohol) and electronic parts (resists coolants) |
| Elastizität | Dehnung in der Pause >500%; Shore hardness 20–80A | Ensures products (Z.B., Telefontasten, O-Ringe) maintain flexibility after repeated use |
| Biokompatibilität | Medical-grade LSR meets FDA 21 CFR §177.2600 | Safe for skin-contact products (Z.B., 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.
Schritt 1: Rohstoffzubereitung & Testen
- Komponentenmischung: Blend LSR main agent and curing agent in a precise ratio (gemeinsam 1:1 oder 10:1) using an automated mixer. For colored products, add 1–3% non-toxic pigments to the mixture.
- Qualitätsinspektion: Benehmen 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).
Schritt 2: Schimmeldesign & Herstellung
Molds are the “heart” of the process—their precision directly impacts product quality.
- Konstruktionsüberlegungen:
- Torposition: Tore platzieren (injection inlets) at thick sections to avoid air traps. Für kleine Teile (Z.B., elektronische Anschlüsse), use pinpoint gates (0.5–1 mm Durchmesser).
- Kühlsystem: Add water channels around the cavity to control mold temperature (±2°C tolerance)—prevents uneven curing.
- Oberflächenbehandlung: Apply chrome plating (5–10μm thickness) or nitriding to the mold surface. This improves wear resistance (extends mold life to 100,000+ Zyklen) and release performance (reduces sticking).
- Manufacturing Equipment: Use CNC machining centers (accuracy ±0.005mm) to mill the mold cavity. Für komplexe Formen (Z.B., Komponenten für medizinische Geräte), add EDM (Elektrische Entladungsbearbeitung) for micro-details.
Schritt 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:
| Parameter | Ideal Range | Impact of Incorrect Settings |
| Lauftemperatur | 40–60 ° C. (zone 1: 40° C; zone 2: 50° C; zone 3: 60° C) | Zu hoch (>70° C) = premature curing (blocks the barrel); zu niedrig (<30° C) = poor flow |
| Injektionsdruck | 15–30 MPa | Zu hoch (>40MPA) = mold deformation; zu niedrig (<10MPA) = incomplete cavity filling |
| Einspritzgeschwindigkeit | 8–15mm/s (staged: slow start → fast middle → slow end) | Zu schnell (>20mm/s) = air trapping (Blasen); Zu langsam (<5mm/s) = cold slugs (uneven texture) |
| Schimmelpilztemperatur | 140–160 ° C. | Zu hoch (>180° C) = over-curing (spröde Teile); zu niedrig (<120° C) = under-curing (sticky surface) |
| Härtungszeit | 10–120 Sekunden (1 second per mm of thickness) | Too short = under-curing; too long = reduced production efficiency |
Schritt 4: Heilung, Entformen & Nachbearbeitung
- Heilung: The mold remains closed for the set time—use a mold temperature controller to maintain stable heat.
- Entformen: Use robotic ejectors (für die Massenproduktion) or manual tools (für kleine Chargen) Teile entfernen. Apply a thin layer of silicone release agent if sticking occurs (avoid excess—causes surface defects).
- Nachbearbeitung:
- Enttäuschung: Trim gate residues with a laser cutter (Für Präzisionsteile) or sharp scissors (für nicht kritische Teile).
- Reinigung: Wash parts with deionized water to remove release agent residue.
- Sekundärvulkanisation (Optional): Für Hochtemperaturteile (Z.B., Kfz -Dichtungen), bake at 200°C for 2–4 hours to improve heat resistance.
3. Vorteile & Herausforderungen: Eine vergleichende Analyse
Silicone mold injection molding has clear strengths compared to traditional manufacturing methods (Z.B., Kompressionsformung, manual casting). It also faces unique challenges—understanding both helps users decide if it’s the right process.
A. Advantages Over Traditional Methods
| Vorteil | Silicone Mold Injection Molding | Kompressionsformung | Manual Casting |
| Produktionseffizienz | Hoch (30–60 parts per minute for small components) | Medium (5–10 parts per minute) | Niedrig (1–2 parts per hour) |
| Dimensionsgenauigkeit | ± 0,01 mm (ideal for precision parts) | ± 0,1 mm (limited by mold pressure) | ± 0,5 mm (human error) |
| Product Consistency | 99.5% Gleichmäßigkeit (automatisierter Prozess) | 90% Gleichmäßigkeit (hängt von Bedienerkenntnissen ab) | 70% Gleichmäßigkeit (high variability) |
| Komplexitätshandhabung | Exzellent (can produce parts with undercuts, Mikrolöcher) | Arm (requires split molds for complexity) | Sehr arm (limited to simple shapes) |
| Materialverschwendung | Niedrig (<5% scrap—excess can be recycled) | Medium (10–15% scrap) | Hoch (20–30% scrap) |
B. Wichtige Herausforderungen & Minderungsstrategien
| Herausforderung | Grundursache | Minderungsstrategie |
| High Initial Investment | Mold manufacturing (CNC -Bearbeitung + Oberflächenbehandlung) Kosten \(10,000- )100,000; injection machines cost \(50,000- )200,000 | – Für kleine Chargen: Use shared molds (reduces cost by 50%).- For long-term projects: Choose high-wear-resistant mold materials (Z.B., H13 Stahl) to extend life (100,000+ Zyklen) |
| 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. Anwendungsfelder: Wo es scheint
Silicone mold injection molding is widely used in industries that demand precision, Haltbarkeit, und Biokompatibilität. The table below highlights key applications with specific examples:
| Industrie | Typical Products | LSR Grade | Key Process Requirements |
| Medizinprodukte | Katheterspitzen, surgical instrument gaskets, baby pacifiers | Medical-grade (FDA 21 CFR §177.2600) | – Cleanroom production (Klasse 100,000).- No release agent (avoids contamination).- Biocompatibility testing post-production |
| Elektronik | Phone buttons, LED lamp seals, sensor O-rings | Industriell (high insulation) | – Hohe Präzision (±0.005mm for button travel).- Low volatility (no VOCs to damage electronics) |
| Automobil | Engine gaskets, fuel system seals, Dashboard -Komponenten | High-temperature grade (resists 250°C) | – Chemischer Widerstand (Öle, Kühlmittel).- Vibration resistance (Verlängerung >500%) |
| Konsumgüter | Silicone kitchen utensils (spatulas), waterproof watch bands | Food-grade (Von der FDA zugelassen) | – Non-toxic pigments.- Glatte Oberfläche (Ra <0.8μm) zur einfachen Reinigung |
5. Yigu Technology’s Perspective on Silicone Mold Injection Molding
Bei Yigu Technology, we see silicone mold injection molding as a cornerstone of high-precision manufacturing—especially for industries like medical and automotive. Für medizinische Kunden, our custom injection molds (Toleranz ± 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 (Z.B., coated aluminum) that cut mold costs by 40% während der Pflege 50,000+ Zyklen; 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.
FAQ
- Was ist die Mindestbestellmenge? (Mindestbestellmenge) for silicone mold injection molding?
MOQ depends on mold cost: Für Standardteile (Z.B., O-Ringe), MOQ is 10,000–50,000 units (Schimmelpilze ausgleichen). Für benutzerdefinierte Teile, we offer shared molds with MOQ as low as 1,000 Einheiten (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% leichte Durchlässigkeit, 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 (CNC -Bearbeitung + Testen). After mold approval, production can start within 1 Woche. Für dringende Projekte (Z.B., medical device emergencies), we offer expedited mold development (2–3 Wochen) with priority production.