What Is the Step-by-Step Process of Making Rubber Prototypes?

Rubber prototypes—crafted from materials like silicone, TPE, TPU, and natural rubber—are critical for validating product functions like elasticity, sealing, and slip resistance. Unlike plastic or metal prototypes, their production requires specialized mold-making and molding processes to leverage rubber’s unique flexible properties. This article breaks down the full process from demand analysis to final testing, with comparisons, technical tips, and real-world examples to help you avoid common pitfalls and create high-quality rubber prototypes.

1. Pré-production: Définir les exigences & Plan Design

Before starting fabrication, clarify testing goals and design parameters to ensure the prototype aligns with your needs. This stage lays the foundation for material selection and process choice.

1.1 Clarify Core Requirements

Rubber prototypes serve three key validation purposes—focus on these to guide your design:

1.2 Design 3D Models with Rubber-Specific Rules

Utiliser le logiciel CAO (Solide, Goût, et) Pour créer un modèle numérique, focusing on parameters unique to rubber:

1.3 Split Complex Parts (Si nécessaire)

For curved or thin-walled rubber parts (Par exemple, a U-shaped sealing strip), split the 3D model into sections. This simplifies mold machining and prevents deformation during demolding. Par exemple:

• A curved silicone earbud prototype is split into “ear tip” and “body” sections—each fits into a smaller mold, reducing the risk of air bubbles compared to a single large mold.

2. Fabrication de moisissures: Choose the Right Method for Your Batch & Précision

Rubber prototypes require custom molds—select between CNC-machined and 3D-printed molds based on precision needs and production volume.

Astuce: Pour le prototypage, start with a 3D-printed mold if you need to test 1–5 units quickly. Switch to a CNC mold if you require 20+ prototypes identiques (Par exemple, for user testing).

3. Processus de moulage: Select Based on Rubber Type & Taille de pièce

The molding method determines the prototype’s precision, élasticité, et coûter. Choose from three common processes based on your material and application:

3.1 Liquid Silicone Injection Molding (LSR)

• Matériaux applicables: Silicone liquide (30°–70° Shore hardness).
• Étapes de traitement:

1. Mix liquid silicone (Partie A + Part B) dans un 1:1 rapport.
2. Inject the mixture into a preheated mold (150°C–200°C).
3. Cure for 5–15 minutes (en fonction de l'épaisseur).
4. Demold and trim excess material.

• Avantages: Haute précision (ideal for micro-parts like phone waterproof rings), excellent elasticity, and no post-curing needed.
• Idéal pour: Transparent medical parts (Par exemple, infusion tube fittings) and high-precision seals.

3.2 Solid Rubber Pressing

• Matériaux applicables: Natural rubber, EPDM, and silicone rubber sheets.
• Étapes de traitement:

1. Cut rubber sheets into the approximate shape of the mold cavity.
2. Heat the sheets to 120°C–180°C to soften them.
3. Press the softened rubber into the mold with 10–20 MPa pressure.
4. Cool for 10–20 minutes, then demold.

• Avantages: Faible coût, fast for large parts (Par exemple, automotive shock absorbing pads), and suitable for aging-resistant materials like EPDM.
• Idéal pour: Sealing strips (Par exemple, joints de porte) and large slip-resistant mats.

3.3 Polyurethane Casting (UR)

• Matériaux applicables: Polyurethane elastomers (TPU, TPE).
• Étapes de traitement:

1. Mix AB components (résine + hardener) dans un 1:1 rapport.
2. Degas the mixture under vacuum (-0.1MPA) Pour éliminer les bulles d'air.
3. Pour the mixture into the mold slowly to avoid eddy currents.
4. Guérir à température ambiante (24 heures) or heat (80° C pour 2 heures).

• Avantages: Mimics rubber’s flexibility, perfect for cladding metal/plastic parts (Par exemple, power tool handles with metal cores).
• Idéal pour: Overmolded prototypes (Par exemple, silicone-coated plastic buttons).

Table de comparaison: Molding Process Selection Guide

4. Post-traitement: Refine & Enhance Prototype Quality

Rubber prototypes require targeted post-processing to fix defects, Améliorer les performances, and add functional details.

4.1 Basic Trimming & Débarquant

• Use a sharp blade or grinding wheel to remove excess rubber burrs (common around mold edges). For small parts like silicone earbuds, use tweezers to peel off tiny burrs—avoid sanding (it can damage soft rubber surfaces).

4.2 Secondary Vulcanization (For Silicone)

• Bake silicone prototypes at 150°C–200°C for 2–4 hours. This step improves temperature resistance (par 30%) and aging resistance (extends lifespan by 50%), critical for automotive or outdoor use. Par exemple:

A silicone automotive seal prototype, after secondary vulcanization, withstands 150°C for 1,000 hours without hardening—vs. 500 hours for an unprocessed version.

4.3 Traitement de surface

Add functional or decorative finishes based on your needs:

• Anti-Slip Coating: Spray epoxy-based anti-slip paint on grips to boost friction (reduces slip by 60% for wet surfaces).
• Impression d'écran en soie: Apply logos, hardness labels (Par exemple, “50° Shore”), or warning text (Par exemple, “Medical Grade”).
• Material Bonding: Use rubber-specific adhesives to attach rubber to metal/plastic (Par exemple, a nylon + rubber overlay for a tool handle).

5. Essai & Optimisation: Validate Performance & Résoudre les problèmes

Test the prototype against your initial requirements, and address common problems like bubbles or deformation.

5.1 Key Test Items

5.2 Solve Common Defects

6. Yigu Technology’s Perspective on Rubber Prototype Production

À la technologie Yigu, we’ve found that the biggest challenge in rubber prototype making is balancing flexibility with precision—many clients rush to choose LSR for high precision but overlook cost for small batches. Our approach is to match processes to needs: for 1–5 units of complex parts, we recommend 3D-printed molds + polyurethane casting (fast and cheap); pour 10+ pièces de haute précision, CNC molds + LSR (durable and accurate). Par exemple, a medical client initially chose LSR for a single silicone tube prototype (coût \(300), but we switched to 3D-printed molds + fonderie (coût \)80) sans sacrifier la qualité. We also emphasize pre-testing material compatibility—e.g., ensuring TPE bonds well with ABS before overmolding—to avoid rework. Rubber prototypes thrive on attention to detail; small adjustments (like adding a 2° draft slope) can save days of troubleshooting.

7. FAQ: Common Questions About Making Rubber Prototypes

T1: Can I use 3D printing directly to make rubber prototypes (sans moules)?

A1: Rarely—most 3D-printed “rubber-like” parts (Par exemple, TPU filaments) lack the elasticity and sealing performance of true rubber. Molding processes (LSR, fonderie) are needed to leverage rubber’s natural properties. For simple concept tests, 3D-printed TPU can work, but for functional validation, use mold-made rubber prototypes.

T2: How do I choose between silicone and TPE for my prototype?

A2: Choose silicone for high temperature resistance (jusqu'à 200 ° C) et transparence (Par exemple, dispositifs médicaux, phone waterproof rings). Choose TPE for better wear resistance and lower cost (Par exemple, poignées, pièces de jouets). Par exemple, a baby bottle nipple prototype uses silicone (non toxique, résistant à la chaleur), while a toy car tire prototype uses TPE (moins cher, durable).

T3: Why does my rubber prototype have a sticky surface?

A3: Sticky surfaces are usually caused by incomplete curing (Par exemple, LSR cured at 140°C instead of 160°C) or excess release oil. Correctifs: Re-cure the prototype at 160°C for 1 heure; wipe excess oil with a lint-free cloth. For silicone, secondary vulcanization also eliminates stickiness by removing residual low-molecular-weight compounds.