Liquid Silicone Rubber
(LSR) Molding
DFocus PROTOTYPE provides high-precision LSR molding services for industries demanding heat resistance, biocompatibility, and flexibility. From medical devices to automotive seals, we offer scalable production for liquid silicone parts.
- Excellent Biocompatibility & Heat Resistance
- High-Volume & Overmolding Capabilities
- Durable, Flexible, and UV Resistant Parts
Medical-grade biocompatible. Overmolding available.
LSR vs. TPE: Critical Comparison
| Property | Liquid Silicone (LSR) | TPE / TPU |
|---|---|---|
| Heat Resistance | Excellent (up to 250°C) | Low (melts ~100°C) |
| Compression Set | Very Low (Bounces back) | Moderate (Deforms over time) |
| Biocompatibility | High (Inert, Hypoallergenic) | Variable |
| Cost per Part | Moderate | Low |
| Tooling Cost | High (Complex) | Low (Standard) |
Medical & Food Grade
Biocompatible and odorless. Ideal for baby products (bottle nipples, pacifiers), medical seals, catheters, and respiratory masks that require sterilization.
Automotive & Industrial
Resists oil, chemicals, and extreme heat. Used for gaskets, O-rings, connector seals, and windshield wiper blades that must withstand harsh environments.
LSR Overmolding Solutions
Combine the rigid strength of thermoplastics/metals with the soft touch and sealing properties of silicone.
Double-Shot Molding
Inject thermoplastic substrate first, then immediately overmold silicone in the same machine cycle. Efficient for high-volume production of water-resistant electronics and ergonomic grips.
Insert Molding
Place a pre-made metal or plastic part into the mold, then inject silicone around it. Perfect for adding seals to metal housings or creating soft buttons on rigid interfaces.
Design for LSR Molding
LSR behaves differently than thermoplastics.
- Flash ManagementLSR has low viscosity and can flash easily (0.0002"). Precision tooling is critical.
- EjectionFlexible parts can often be manually pulled or air-ejected without ejector pins.
- UndercutsSoft silicone can stretch over undercuts, simplifying mold design compared to rigid plastics.
Alternatives to LSR
Not ready for LSR tooling? Consider these options:
Vacuum Casting
Using silicone molds to cast polyurethane resins that mimic rubber. Great for low-volume prototypes (10-50 pcs).
TPE/TPV Injection Molding
Thermoplastic elastomers process like standard plastic but feel like rubber. Cheaper tooling but lower heat resistance than LSR.
LSR Molding FAQ
What is the difference between LSR and TPE?
LSR (Liquid Silicone Rubber) is a thermoset, meaning it cures permanently and won't melt, offering superior heat/chemical resistance. TPE (Thermoplastic Elastomer) can be re-melted and is generally cheaper to process but has lower performance limits.
Why is LSR tooling more expensive?
LSR tooling requires extremely tight tolerances to prevent flash due to the material's low viscosity. It also requires specialized cold-deck systems to keep the silicone liquid before injection into the heated cavity.
Can you bond LSR to plastic?
Yes, through overmolding. However, since LSR doesn't chemically bond to most plastics easily, we design mechanical interlocks (undercuts, holes) or use specialized self-bonding LSR grades depending on the substrate (e.g., Nylon, PC).
Precision LSR Molding
Get high-quality silicone parts for medical, automotive, and consumer applications.
Get LSR Quote