Sunday, February 5, 2012

Gasket Material and Selection

Most major manufacturing sectors, including the automotive, aerospace, electronics, appliance, and military industries, employ gaskets in their production methods. A gasket is a sealing device made of deformable material usually designed in the form of a ring or sheet. Gaskets create a pressure-tight seam between multiple stationary components, relying on a compression seal to prevent unwanted gas or liquid emissions. These seals are often intended to be resistant to pressure, temperature fluctuations, and in some cases, electrical or electromagnetic forces. Since it uses compression, a gasket is typically more malleable than the components it joins and is able to conform to the shape of the harder surfaces between which it is placed.

Gaskets are available in a large number of specifications, making proper gasket selection an important step in many manufacturing processes. They can be formed from a wide range of materials, such as metals, rubbers, plastics, corks, foams, and composite substances. They also come in numerous designs, including jacketed, double-jacketed, spiral wound, and Kammprofile varieties. Finding the right combination of material and design depends on the gasket’s specific uses and the cost parameters of the project.

Is a Gasket Necessary?

While gaskets serve an important function as sealing joints, there are a handful of similar devices that may be better-suited to certain tasks. An application requiring a seal that forms a barrier between external and internal elements, such as a unit to prevent water leakage, usually needs a gasket. However, to fill small assembly gaps between components, manufacturers would be better served by a spacer, or “shim,” which is a narrow wedge used for packing or leveling purposes.

Likewise, o-rings, though similar to gaskets, have a subtly different designation. Unlike gaskets, o-rings are made almost exclusively of synthetic rubber or plastic polymers with elastomeric properties, and are produced solely in ring form. They are durable and reliable in sealing matched components by creating a barrier around an area with leakage potential. In addition, o-rings are distinct for their round or square cross-sectional configurations, as well as their high pressure resistance, making them valuable in some applications where a standard gasket’s resistance would not suffice.

Gasket Specifications

After determining that a gasket—as opposed to a shim or an o-ring—is the appropriate device for a given application, several other factors must be taken into account to choose a well-suited design. There are numerous types of gaskets, though many share similar features and may be capable of handling related tasks. Some of the most common varieties of gasket include:

Jacketed Gaskets: This form merges the efficiency and flexibility of soft gaskets (made of rubber or plastic) with the resistance and durability of an external metal coating. A single-jacket has soft filler with metal coverage along one face of the gasket, while a double-jacketed version has a fully coated metal facing, providing improved temperature, pressure, and corrosion resistance. Other variations include corrugated jacketed gaskets, and French Style jackets, which provide coating on either the inside or outside of the gasket.

Solid Gaskets: Solid gaskets are typically formed of metal and are a relatively inexpensive alternative to jacketed gaskets. They have high thermal and pressure resistance, though they require higher compression force to form a seal and are usually effective only against surfaces that are harder than the metal itself.

Spiral Wound Gaskets: This type of gasket is formed by combining metal with softer plastics or synthetic rubber in a winding shape, often reinforced with additional layers of metal without filler. Its unique design yields high thermal and physical stress resistance, coupled with flexibility and resilient sealing. Spiral wound gaskets are often used in piping, pumping, and heat exchange systems.

Kammprofile Gaskets: The Kammprofile design contains a corrugated metal core covered with a malleable sealing material attached to both of its sides. This structure focuses physical stress onto the surface sealant, creating tight seals along the gasket’s edges while retaining the device’s flexibility and strong tensile core. Kammprofile gaskets provide reliable support in heat exchange systems and have improved cost-effectiveness due to their capacity for repair.

Metal Gaskets

Many types of gaskets are constructed from metal or a mixture of metal and non-metal materials. These gaskets are typically formed with aluminum, copper, nickel, steel, stainless steel, or brass. These materials provide a high level of thermal, corrosive, and pressure resistance, along with excellent durability and tensile strength. On the other hand, metals require elevated amounts of compressive force to form a seal and have limited flexibility for multiple applications. For these reasons, metals are often used in combination with rubber or plastic compounds, otherwise known as “soft fillers.” Rubber and Plastic Gaskets

Due to its elastomeric properties, rubber is a popular material for gasket production. Since they can undergo a high degree of deformation without permanent damage or loss of attributes, rubber gaskets can form very tight seals within a wide range of applications. Some types of rubber frequently used in gasket manufacturing include nitril, viton, and neoprene. Certain polymers, such as thermoplastic elastomer, thermoplastic rubber, and polyvinyl chloride, display qualities similar to those of rubber and are also common in gasket production. Silicone Gaskets

Silicone is a valuable gasket material because it displays strong resistance to extreme temperatures. Silicone-based gaskets can have operating temperatures that range between roughly -140 degrees to 480 degrees Fahrenheit. In addition, their resistance to ultraviolet light makes them useful in outdoor settings, while their flame tolerance within a certain thickness range has applications in electronics and transit industries. Silicone gaskets come in foam and sponge varieties, and can be reinforced with other materials to improve tensile strength or adjust thermal and electrical conductivity. Compression Testing

An important characteristic for industrial gaskets is their capacity for tolerating compressive loads. Evaluations, such as the hot compression test, can be used to gauge a specific gasket’s ability to withstand various weights and temperatures. Typically, a gasket is placed between the exertion bolts of a hydraulic press. Temperature is increased, often up to nearly 600 degrees Fahrenheit, at an incremental rate over a given period of time while the press exerts constant load pressure on the gasket. Any decreases in material thickness are measured and used to assess the gasket’s effectiveness. Tests such as this can be helpful in selecting a gasket or deciding upon a given material or design configuration.

1 comment:

  1. A silicone gasket is very useful and used in our day a day appliances and thank's to it we can do things like open the tap without water loss!