Vacuum systems are used in a wide range of applications, from scientific research to industrial processing. In order to achieve the desired performance, these systems require fasteners that can withstand high temperatures, pressures, and corrosive environments while maintaining a vacuum-tight seal. Polymers such as PEEK and PPS are well-suited for this purpose, offering a range of benefits over traditional metal fasteners.
PEEK (polyether ether ketone) is a high-performance polymer that is known for its excellent mechanical properties, high temperature resistance, and chemical resistance. It is commonly used in vacuum systems because it is lightweight, strong, and has a low outgassing rate. PEEK fasteners are also resistant to many common solvents and chemicals, making them ideal for use in harsh environments.
Another important advantage of PEEK fasteners is their ability to maintain a vacuum-tight seal. Vacuum systems require a tight seal in order to maintain the desired level of vacuum. PEEK fasteners can provide this seal even under high temperatures and pressures, ensuring that the vacuum remains stable and consistent.
PPS (polyphenylene sulphide) is another high-performance polymer that is commonly used in vacuum systems. Like PEEK, PPS is known for its high temperature resistance and chemical resistance. It is also a good choice for applications that require high strength and dimensional stability.
One of the key advantages of PPS fasteners is their ability to withstand high temperatures without degrading or losing their strength. This makes them ideal for use in high-temperature vacuum systems, such as those used in semiconductor processing or aerospace applications.
Venting is an important consideration in vacuum system design. In order to maintain a stable vacuum, it is necessary to remove any gas that enters the system. Venting can be achieved through the use of specialised fasteners that incorporate vent holes or through the use of separate venting components.
Vent holes can be incorporated into fasteners made from PEEK and PPS, allowing gas to escape from the system without compromising the vacuum-tight seal. The location and size of the vent holes must be carefully designed to ensure that they do not interfere with the performance of the fastener or the vacuum system as a whole.
In addition to vent holes, specialised fasteners such as vented screws and bolts can be used to provide venting in vacuum systems. These fasteners incorporate a hollow core that allows gas to escape from the system. Vented screws and bolts are typically made from materials such as titanium or stainless steel, which are compatible with vacuum environments.
When designing a vacuum system, it is important to select fasteners that are compatible with the materials used in the system. This includes not only the materials used in the vacuum chamber but also any materials used in the manufacturing process.
One potential issue with using PEEK and PPS fasteners in vacuum systems is that they can release gases as they are exposed to high temperatures. This is known as outgassing and can be a significant problem in vacuum systems, particularly those used in scientific research.
To minimise outgassing, it is important to select fasteners that have a low outgassing rate. PEEK and PPS fasteners are typically processed to reduce their outgassing rate, making them suitable for use in vacuum systems.
In addition to PEEK and PPS, there are a number of other high-performance polymers that are suitable for use in vacuum systems. These include materials such as PVDF (polyvinylidene fluoride) and PTFE (polytetrafluoroethylene).
PVDF is a high-performance polymer that is known for its excellent chemical resistance and high temperature resistance. It is commonly used in vacuum systems because it has a low outgassing rate and can withstand exposure to a wide range of chemicals and solvents.