Deltron Enclosures, part of the Alpha 3 Manufacturing group, explains the role gaskets play in enclosure sealing and outlines how to choose the right material for your application.
Put simply, a gasket is a seal between two components to prevent leakage and ingress of dust particles, water, oils, chemicals and more.
At Deltron Enclosures, they are used in our aluminium and plastic enclosures to provide an IP rating and sometimes for EMI/RFI protection.
So, why don’t we call it a seal? There is a difference between gaskets and seals; a gasket is also known as a static seal which depends on the two mating components being static. In contrast, a seal is used to prevent leakage between two kinetic parts, for example, a pump or a rotary type motion in an engine. A seal is generally rounded and flat, while a gasket is shaped to fit the necessary components.
Gaskets can be made from different materials, depending on the properties of the material and the demands of the application. Popular options include rubber, neoprene, silicone, cork, graphite and foam plastic. At Deltron, we use neoprene and silicone rubber. The two can be used in different ways to create the desired sealing performance.
The right material
Choosing the best material for your gasket is essential to ensure performance and longevity. In the majority of applications, exposure to the elements is a critical consideration. Snow, sleet, heavy rain, UV, plus rising and falling temperatures can affect the gaskets’ sustainability; some materials may crack, or fluctuating temperatures could cause a gasket to expand or freeze and consequently fail to prevent ingress.
With neoprene sponge, an open-cell type with an adhesive backing, the adhesive allows the gasket to be attached to the enclosure lid to ease the assembly process. Neoprene sponge is used with our general-purpose IP66 thin-wall die-cast enclosure ranges and has several useful properties:
- A resilient material, repels dust and moisture
- Good resistance to petrol, oils and chemicals
- Can be made with adhesive backing to aid fitting
- Can withstand high levels of compression
Silicone Rubber is a closed-cell type material with an adhesive backing. Silicone rubber sponge is used with our general-purpose IP68 thin-wall die-cast enclosure ranges as well as the heavy-duty thick wall IP66 and IP68 ranges and also has several useful properties:
- Excellent resilience to extreme high and low temperatures
- UV and ozone resistant; ideal for outdoor application
- Being an inert material, it does not react to the majority of chemicals; ideal for medical or industrial applications
Carbon loaded silicone rubber gaskets are conductive and are used to connect the lid electrically to the base whilst still achieving IP68 protection. The electrical connection improves the enclosure’s EMC performance, helping to keep radio frequency interference inside or outside the enclosure.
Thin wall general-purpose enclosures have shallow lids, so it is possible to over compress the gasket underneath the screws and create leaks away from the screws where the lid bows upwards. It is recommended that users comply with the torque settings in figure 1.
|IP rating||Gasket material||Lid screw torque Nm|
|IP66||Open cell neoprene||0.3Nm|
|IP68||Closed cell silicone||0.7Nm|
|IP68||Solid carbon loaded silicone||1.0Nm|
However, Deltron’s heavy-duty thick wall enclosures have an innovative two-level gasket face that allows the metal lid to touch the base’s metal whilst allowing the perfect level of gasket compression whatever torque is used. This also means that a conductive gasket is not needed because metal touches metal.
The Deltron heavy-duty enclosures are IP68 certified at the unusually severe specification of 10m submersion for 20 hours. Many people ask what happened at 20 hours, did it fail? The answer is no, we just ran out of time.