(e.g., silicone, TPU, TPE)
or molds themselves made from softer materials (e.g.,
aluminum, silicone) for prototyping or low volume production. Here’s a detailed breakdown:
1. Types of Soft Plastic Molds
A. Molds for Soft/Flexible Plastics
Used to shape materials like:
TPU (Thermoplastic Polyurethane) : For phone cases, shoe soles.
TPE (Thermoplastic Elastomer) : For grips, seals, medical devices.
Silicone : For kitchenware, medical tubing, baby products.
Key Requirements :
Flexible ejection systems (to avoid part deformation).
Textured surfaces for grip or aesthetics.
Precise cooling to prevent warping.
B. Soft Tooling (Mold Material)
Molds made from softer materials for prototyping or short runs :
Aluminum Molds : Cheaper and faster to machine than steel, suitable for <10k parts.
Silicone Molds : Used for low pressure casting (e.g., resin, urethane prototypes).
3D Printed Molds : Made from ABS, resin, or nylon for <100 parts (fast but less durable).
2. Design & Manufacturing
Mold Material :
Aluminum : Good for low volume TPE/TPU parts; faster cooling than steel.
Silicone : Ideal for intricate shapes (e.g., microfluidic devices).
Surface Finish : Texturing (e.g., grit blasting) to enhance part grip.
Ejection : Rubberized ejector pins or air blasts to prevent part sticking.
Venting : Critical for soft materials prone to air traps.
3. Applications
Consumer Goods : Phone cases, ergonomic grips, silicone baking molds.
Medical : Soft touch syringe components, respiratory masks.
Automotive : Seals, gaskets, vibration damping pads.
Toys & Wearables : Squishy toys, fitness bands.
4. Advantages
Cost Effective : Soft tooling (e.g., aluminum) reduces upfront costs.
Fast Turnaround : 3D printed/silicone molds can be made in days.
Complex Geometries : Soft materials fill intricate details easily.
5. Challenges
Durability : Soft molds wear faster than steel (e.g., aluminum lasts ~10k cycles).
Surface Detail : Softer molds may struggle with high gloss finishes.
Material Limitations : Silicone molds can’t handle high temperature plastics.
6. Soft Plastic Molding Techniques
Injection Molding : Standard for TPU/TPE parts with aluminum/steel molds.
Compression Molding : Used for silicone (e.g., oven mitts, seals).
RTV (Room Temperature Vulcanization) : Silicone molds for casting urethane prototypes.
Example Workflow
1. Design : CAD model → draft angles for easy ejection.
2. Mold Fabrication : CNC machining (aluminum) or 3D printing (resin).
3. Molding : Inject TPU/silicone → cool → eject.
4. Post Processing : Trim flash, surface finishing.
