Choosing the right materials for silicone Vacuum casting is make-or-break for your project—whether you’re making small-batch prototypes or low-volume production parts. The process relies on three core material types: prototype materials (to create the master template), mold materials (to make the flexible silicone mold), e casting materials (to produce the final parts). Abaixo, we break down each category with clear data, use cases, and tips to help you pick the perfect materials for your needs.
1. Prototype Materials: O “Template” for Your Silicone Mold
The master prototype is the foundation of silicone vacuum casting—its material directly impacts how well the mold captures details and how durable the template is. Two main techniques are used to make prototypes, each with specific material strengths:
| Prototyping Technique | Materiais comuns | Propriedades -chave | Melhor para | Performance Data |
| Usinagem CNC | Abs, Alumínio, Stainless Steel | Alta precisão, acabamento superficial liso | Prototypes needing tight tolerances (Por exemplo, engrenagens, peças mecânicas) | Tolerâncias: ±0.01mm; Acabamento superficial: Ra 0.2–0.8μm |
| SLA 3D Printing | Resinas de fotopolímeros (Por exemplo, Formlabs Grey Resin) | Complex shape capability, fine detail capture | Intricate designs (Por exemplo, textured phone cases, small medical device components) | Acabamento superficial: Ra 0.1–0.3μm; Detail resolution: 0.025mm |
Practical tip: If you’re making a prototype for a functional part (like a hinge), CNC-machined ABS is better—it has a higher impact strength (20 KJ /) than SLA resins (10–15 kJ/m²). For decorative parts with tiny patterns, Impressão SLA 3D is the way to go, as it can replicate details as small as a grain of sand.
2. Mold Materials: Flexible Silicone for Replicating Details
The mold material in silicone vacuum casting is almost always Rtv (Room Temperature Vulcanization) silicone—a liquid that cures into a soft, elastic mold capable of capturing every detail of the master prototype. There are two main types of RTV silicone, each suited to different project needs:
| Mold Material Type | Propriedades -chave | Mold Life (Uses) | Shrinkage Rate | Custo (Por kg) | Melhor para |
| Addition-Cure Silicone | Low shrinkage, high durability, no odor | 20–50 | 0.1–0.3% | \(25- )40 | High-volume low runs (30–50 peças) or complex prototypes (Por exemplo, peças com undercuts) |
| Condensation-Cure Silicone | Lower cost, faster cure, slight odor | 10–20 | 0.5–1.0% | \(15- )25 | Pequenas corridas (10–20 peças) or simple shapes (Por exemplo, basic housings) |
Por que isso importa: A low shrinkage rate (like 0.1–0.3% for addition-cure silicone) ensures your final cast parts match the master prototype’s size almost exactly. Por exemplo, if your prototype is 10cm long, an addition-cure mold will produce parts that are 9.997–9.999cm long—critical for parts that need to fit together.
3. Casting Materials: O “Final Part” Materiais
Casting materials are what you inject into the silicone mold to make your end product. They range from common plastics to specialized rubbers and 耐高温 (high-temperature resistant) Materiais, each tailored to specific performance needs:
| Casting Material Type | Specific Materials | Propriedades -chave | Typical Applications | Performance Highlights |
| Thermoplastic-Like Resins | Abs, PC, Pp, PA, PMMA | Mimic production plastics; good strength/durability | Consumer electronics (Casos de telefone), automotive accessories (botões), household goods (container lids) | – Abs: Impact strength 20 KJ /- PC: Heat resistance up to 120°C; 透光率 (Transmitância de luz) 88%- PMMA: 透光率 92% (close to glass); resistente a arranhões |
| Flexible Materials | Rubber, Soft PU Resins | Elasticity, grip, shock absorption | Grips (Controles remotos), vedações (water bottles), O-rings (pipes) | Shore hardness: A 30–60; Elastic recovery rate >90% |
| High-Temperature Resistant Materials | PPS, PEI, Silicone Rubbers | Withstand extreme heat (150–250 ° C.) | Componentes do motor, industrial sensors, high-heat tools | – PPS: Heat resistance 220°C- PEI: 250° c; chemical resistance to oils/solvents |
| Materiais Especiais | PVC, Conductive Resins | Customizable hardness (PVC); electrical conductivity (conductive resins) | Cable insulation (PVC), electronic connectors (conductive resins) | – PVC: Hardness range Shore A 60–D 80- Conductive resins: Resistivity <10⁻³ Ω·cm |
Cost note: Thermoplastic-like resins (Por exemplo, Abs, PC) custo \(18- )30 por kg, while high-temperature materials (Por exemplo, PEI) can cost \(50- )80 por kg. This makes thermoplastics a better choice for budget-sensitive projects without extreme heat needs.
4. Key Factors to Choose the Right Materials for Your Project
With so many options, it’s easy to feel overwhelmed. Use these 5 factors to narrow down your choices—they’ll help you balance performance, custo, and usability:
- Functional Needs: If your part needs to be transparent (Por exemplo, a lens), pick PMMA or transparent PC. If it needs to handle heat (Por exemplo, a coffee maker part), go for PPS or PEI.
- Tamanho do lote: Para 30+ peças, use addition-cure silicone (longer mold life) to avoid re-making molds. For 10–20 parts, condensation-cure silicone saves money.
- Prototype Complexity: Intricate designs (Por exemplo, tiny text) need Impressão SLA 3D with photopolymer resin—CNC machining can’t capture ultra-fine details.
- Custo: If you’re testing a new design, start with cheaper materials (Por exemplo, condensation-cure silicone + PP resin) before upgrading to higher-cost options.
- Processing Ease: Peças flexíveis (Por exemplo, garras) are easier to cast with soft PU resins—they demold faster than rigid materials and don’t crack the silicone mold.
Perspectiva da tecnologia YIGU
Na tecnologia Yigu, we believe material selection for silicone Vacuum casting should align with both project goals and budget. For clients making functional prototypes, we often recommend CNC-machined ABS for masters (precisão + durabilidade) and rigid PC/PA casting resins (mimic production parts). For complex, decorative parts, Impressão SLA 3D + addition-cure silicone works best—captures details while keeping mold costs low. We also guide clients away from over-specifying: if a part doesn’t need high heat resistance, choosing PC over PEI cuts costs by 50% without sacrificing quality. Our goal is to help you get the right materials for the job, not the most expensive ones.
Perguntas frequentes
- I need to make transparent parts—what casting material should I use?
Opt for PMMA or transparent PC. PMMA has a higher 透光率 (92% vs.. PC’s 88%) and is cheaper (\(25- )30/kg vs. PC’s \(28- )35/kg), making it better for non-heat-exposed parts (Por exemplo, tampas de exibição). If the part needs to handle mild heat (up to 120°C), choose transparent PC for extra durability.
- How long does a silicone mold last, and what affects its life?
Mold life depends on the material: addition-cure silicone lasts 20–50 uses, enquanto condensation-cure lasts 10–20. Factors like casting material (abrasive resins wear molds faster) and demolding care (pulling parts gently vs. tearing) also matter. To extend life, use mold release spray and avoid casting high-temperature resins (over 200°C) in standard RTV silicone.
- Can I use silicone Vacuum casting for food-safe parts?
Yes—but you need food-grade materials. Escolher FDA-approved silicone para moldes (Por exemplo, Dow Corning 734) and food-safe casting resins (Por exemplo, food-grade PP or silicone rubber). Avoid materials like PVC (not food-safe) and always ask for certification to ensure compliance with safety standards.
