Silicone rubber is an elastomer which has many unique properties enable the extensive use of silicone rubber for different applications in the medical, food, aerospace and consumer industries.
What are the different types of silicone?
* FSR-Fluorosilicone Rubber
* HCR-High Consistency Rubber (or solid silicone rubber)
* LSR-Liquid Silicone Rubber
* RTV-Room temperature Vulcanize
Like silcione, fluorosilicone rubber is a long lasting elastomer that is stable, typical applications include aerospace fuel system components, diaphragms, gaskets, hose lining, seals and O-rings.
HCR vs LSR
Based on the different cure and processing methods, silicone rubber can be classified as solid silicone (HCR) and liquid silicone (LSR).
HCR is produced as gummy, high viscosity solid rubber that as partially vulcanzied. Process ways includes: compression molding, transfer molding, and extrusion of rubber tubing.
LSR on the other hand are supplied in drum or pails in liquid rubber form, due to their low viscosity, injection molding is the perfect way to process LSR.
HCRs are less expensive than LSRs both for raw material and tool mold cost. HCR’s methods are better suited for smaller production runs, while LSR is a better fit when making thousands or millions of parts.
RTV vs HTV
In terms of polymer employed and the curing process, silicone rubbers can be divided into room temperature vulcanze rubbers(RTV) and high temperature vulcanze rubbers(HTV). RTV silicone rubbers come as a soft paste or a viscous liquid. HTV silicone rubbers come in two different physical states: liquid and solid.
The above are various types of silicone rubber, in this post, we will focus specifically on the HCR silicone rubbers special properties and their applications.
Silicone materials classification and their characteristics, and applications
Silicone rubbers have exhibited excellent properties, such as thermal conductivity, fire resistance, good chemical stability, flame retardancy, and excellent resistance to heat and cold, etc. By changing the base polymer, adding reinforcing filler and special additives, parts of properties will be strengthen significantly to meet special application needs, silicone rubber will be classified based on their standout properties.
1. General purpose silicone rubber
General purpose silicone rubber has the basic feature of silicone, heat resistance, flame retardance, chemical stability, UV resistance, etc, it can be used to fabricate any commonly used silicone products such as kitchenware. Generally, if products have no special application need, general purpose silicone material will be used. The normal hardness range from Shore A 30 ~70 in cure state.
2. Low hardness silicone rubber
This kind of silicone has very low hardness Shore A 5~20.
Feature: high strength, low hardness, and high elongation, very soft
Application: baby nipple, fresh keeping film, anti-slip mats, shoes insole.
3. High hardness silicone rubber
Material hardness up to Shore A 90 after curing.
Feature: high hardness and rigidity, high dimensional stability
Application: an alternative to thermoplastic or thermosets
4. High tear strength silicone
The tear strength of general silicone is about 9.8 kN/m, high strength silicone can be 29~49 kN/m, ideal for molding items which require high tear strength.
Feature: excellent tear resistance, high tensile strength, high elongation
Application: silicone stretch & seal lids, silicone bands, remote control cover.
5. High transparency silicone
This kind of silicone are highly transparent with good strength.
Feature: super transparency, high tear strength, easy to color with color pigments.
Application: medical tubing, silicone nipples, silicone cases
6. Flame retardant silicone
Silicones are flammable, they can be burned into white ash, however by adding a small amount of flame retardant, silicone can be complied with UL94 V-0, V-1 or V-2 standards.
Feature: flame retardant, no poisonous gases released
Application: consumer electronics, subways, wires and cables, electricity meters
7. Thermal conductive silicone
They are designed with high thermal conductivity and heat resistance.
Feature: High thermal conductivity, electrical insulation, heat resistance
Application: thermal conductive gasket, heat transfer pads, computer CPU, power supplies
8. Electrically conductive silicone rubber
They are silicones filled with electrically conductive material carbon black.
Feature: electronic conductivity, low amperage conductor, thermal conductivity
Application: keypads, cable connectors, gaskets, wahsers.
9. High heat resistance silicone rubber
They are designed for use in challenging environment with temperature up 250 ~ 300°C in certain period.
Feature: high temperature capability
Application: heat resistant cots and seals, auto parts
10. Oil resistant silicone rubber
They are special made silicone with better oil resistance at higher temperature.
Feature: excellent oil resistance
Application: gasketing applications, O-rings and seals
From above we can see silicone materials are formulated into so many different types, so choosing the best fit material is crucial to your project success, please inform us in advance your specific application needs so we can recommend the right material for your cases.
HB Silicone is manfacturer of custom silicone products, we will work with you to develop your custom rubber product that meets your exacting standards and requirements for your unique application.
To find out more about our custom silicone products, please feel free to contact us at any time.