There are many options when it comes to choosing a rubber seal. The profiles can be made of elastomeric compounds through the process of molding or extrusion. The lengths needed for the application are then custom-fabricated from standard rubber products.
There are many different rubber molding processes, including injection, compression, transfer molding, and extrusion. Each process has its own unique advantages, but extrusion is capable of producing complex cross-sections and a smooth surface. These options are available with several different seals, including bulb, bulb trim, lip, door, and accordion seals. There are also extrusions available in solid rubber and sponge rubber, which may then be converted into specialty seals to suit your needs.
There are five different types of extruded seals to consider:
Bulb Seals
Bulb seals have either open, rounded, or teardrop-shaped areas that give them their characteristic look. There are less common shapes as well, such as the crescent and the flat-bottom. Physical dimensions vary, but they usually refer to the height of the inner and outer diameters. Bulb gaskets are typically made of sponge rubber, and are often placed within the door frame of a car or building. Softer bulb seals can be made with EPDM foam in order to create a watertight seal. When used in the automotive industry or construction, bulb seals may be taped instead of mechanically fastened.
Bulb Trim Seals
Bulb trim seals have both a bulb section and a trim section, each with its own durometer. The bulb is usually made from a medium-density sponge rubber such as EPDM. The trim portion is made from materials such as PVC. This unique design allows bulb trim seals to resist water, ozone, sunlight, and temperature extremes. They also come in thermoplastic elastomers, which are weather-resistant, reusable, and recyclable.
Lip Seals
Lip seals have an edge or sealing lip, and sometimes even an opening. Lip seals protect bearings attached to rotating shafts or bores. They retain the lubricant of the bearing, while also preventing dust and other contaminants from entering the seal. One variation on this seal is the radial lip, used in high-speed crankshaft mechanisms found in diesel and gasoline engines.
Lip seals are common in other applications, such as various industrial machines, vehicles, pumps, and mills. If you need this type of seal, choose a material with the right properties for your application.
Door Seals
As their name implies, door seals fill gaps between doors and door frames in order to keep the elements out of vehicles and buildings. Unlike the other extruded seals on this list, door seals are defined by the application they are used in, rather than their shape. Door seals are commonly found in cars and trucks, as well as construction, residential, and industrial facilities. A subset of the door seal known as the hatch seal is used in fuel tanks, electronic enclosures, and rooftop HVAC systems. Certain types of bulb seals also fall under the category of door seals, but these door seals have custom weather stripping as well.
Accordion Seals
Like accordions, accordion seals have folds which allow them to change their dimensions when stretched or compressed. This property makes seals like the accordion boot seal useful in automotive and transportation applications, such as weather-proofing the access points between a truck cab and a trailer. Accordion seals are made from EPDM rubber, and may even contain an internal spring steel loom.
To learn more about the extruded seals available for your application, contact the experts at Real Seal today.
