General properties of silicone rubber
- Wide service-temperature range: commonly around −50°C to +200°C, with specialty formulations exceeding this for short periods.
- Weathering resistance: strong resistance to UV, ozone and oxygen.
- Chemical inertness and biocompatibility: selected grades can meet food-contact or medical requirements when appropriately certified.
- Electrical insulation: stable dielectric behavior across a broad temperature range.
- Hydrophobic surface: helps repel water and moisture.
Silicone is usually selected when heat resistance, weatherability, cleanliness and stability are priorities. For heavy abrasion or highly loaded mechanical service, other elastomers such as polyurethane or certain organic rubbers may be more suitable.
RTV — Room Temperature Vulcanizing silicone
RTV cures at room temperature and generally requires no dedicated heated molding equipment.
RTV categories
- RTV-1: one-part systems, commonly moisture-cured, widely used for sealants and adhesives.
- RTV-2: two-part base-and-curing-agent systems mixed before use, commonly used for molds, prototyping and potting.
RTV-2 systems commonly use two cure mechanisms:
- Condensation cure: practical and cost-effective, typically with some shrinkage and lower dimensional stability than platinum systems.
- Addition / platinum cure: very low shrinkage, good detail reproduction and strong dimensional stability.
Typical RTV applications
- Flexible molds for resin casting, candles, soap and decorative parts.
- Sealing, gasketing and heat-resistant silicone adhesives.
- Electrical and electronic potting or encapsulation.
- Food-contact molds when using appropriately certified materials.
HTV — High Temperature Vulcanizing silicone
HTV, also commonly called HCR (High Consistency Rubber), is a gum-like silicone that requires heat to cure and is well suited to industrial continuous or batch processing.
- Gum consistency and usually processed by milling and forming before cure.
- Can use peroxide or platinum cure systems depending on formulation.
- Suitable for extrusion, compression molding, transfer molding and calendering.
Typical HTV applications
- Industrial and medical tubing.
- Heat-resistant seals and gaskets.
- Wire and cable insulation.
- Industrial rollers.
- Silicone sheet and heat-resistant belts.
LSR — Liquid Silicone Rubber
LSR is a two-part liquid silicone generally metered and mixed automatically before curing in a heated mold using LIM (Liquid Injection Molding).
- Two liquid components, with many commercial systems supplied at 1:1 ratio.
- Low viscosity supports thin walls, fine features and complex mold filling.
- Fast cycles and high automation with minimal finishing.
- Well suited to medical, food-contact and electronics applications when the selected grade carries the necessary approvals.
Typical LSR applications
- Medical valves, membranes and precision components.
- Baby-care products.
- Automotive seals and sensing components.
- Waterproof keypads and consumer-electronics seals.
- High-volume, high-precision molded parts.
RTV vs HTV vs LSR
| Criteria | RTV | HTV / HCR | LSR |
|---|---|---|---|
| Material form | Liquid / paste | Solid gum | Liquid |
| Cure | Room temperature | Heat cure | Heat cure in closed mold |
| Components | 1 or 2 | Depends on system | 2 (A + B) |
| Processing | Pour, brush, dispense | Extrusion, compression, calendering | LIM injection molding |
| Detail capability | Medium – high | Medium – high | Very high |
| Equipment investment | Low | Medium – high | High |
| Suitable volume | Low – medium | Medium – high | High – very high |
Which silicone family should you choose?
- Production volume: flexible low-volume work → RTV; stable high-volume production → HTV or LSR.
- Part complexity: simple parts → RTV/HTV; thin walls, tight tolerances and complex geometries → LSR.
- Equipment budget: lower investment → RTV; long-term automation → LSR.
GKTECH and RTV silicone
GKTECH focuses on RTV silicone for mold making, prototyping and sealing applications. For selection by hardness, viscosity, working time, mix ratio or surface requirement, send the application details to our technical team.
Email: gktech@gktech.vn
Hotline: +84 36 262 1886