LSR: Liquid Silicone Rubber
HCR: High Consistency Rubber
RTV: Room Temperature Vulcanizing
Silicone materials are available in two major forms; a low viscosity Liquid Silicone Rubber or LSR, used in Injection molding, and a higher molecular weight and higher viscosity material, HCR or High Consistency Rubber. HCR is used primarily in compression molding and transfer molding. There are other RTV or Room Temperature Vulcanizing materials, gels, adhesives, dispersions, silicone caulking compounds available, but they are not commonly used in molding applications.
For both forms of silicone materials, the cure mechanism is an important feature. They are also divided into two major forms; Peroxide cure and Platinum cure. Platinum cure gives us faster cure times and less volatiles, or chemical by products, in the material. Peroxide cure is a slower cure material which requires post baking in an oven after molding to remove any volatiles. The post baking is required for medical components.
The material hardness or Durometer is measured in the Shore A range. Materials are available from Shore 5A to 80A.
Silicone materials are then formulated to be either multipurpose or serve specific properties. Some of these purposes are high tear resistant, high temperature, electrically conductive, low compression set, low coefficient of friction, self-adhesive, and oil exuding or self-lubricating properties.
We will discuss further in our Molding Methods and Material Selection section regarding what to choose for your application.
General or multipurpose: Available in 5A-80A Durometer. For applications in Seals, Gaskets, Valves, Diaphragms, consumer goods and consumer electronics.
F-LSR: Fluorosilicones used in applications requiring good chemical resistance to fuels and oils.
Low COF: Low coefficient of friction
High Tear Resistance: Rated highly when tested with in accordance with ASTM D 624B
Low Compression Set: Ability to recover back to original height
Self-Adhesive: For over molding on Nylon, PBT, PET and PC
Oil Exuding: Also known as oil bleeding. Used in electrical and automotive connectors and seals.
Electrically Conductive: Available in 10 ohm-cm, 5 ohm-cm and 0.1 ohm-cm volume resistivity.
High Transparency or Optical: Used in LED lighting and other optical applications.
Flame Retardant: For applications in fire safety.
High Heat Resistance: High temperature resistance for automotive and aerospace applications.
Pick a color which suits your needs. We will match any color with a pantone number or description.