Simply put, a gasket seal prevents a liquid or air (most often) from going somewhere you don’t want it to go or doing something you don’t want it to do.
Gaskets can be made of metal, plastic, silicone, polymers, neoprene, foam, or rubber. A majority of the time, an adhesive holds them in place, depending on the application (of which there are literally thousands). Yet, not all gasket applications require an adhesive. For instance, some are held on by mechanical fasteners: bolts (classic car engine) or screws (watch).
None of this is news to you, likely, but here’s something new. Think of gaskets as the function it performs, not the construction of the piece itself (its material or shape). So, a gasket can simply be a piece of 3M VHB tape used in a cell phone screen to prevent rainwater from entering, or a piece of double sided tape used within a membrane switch touch panel.
Now, let’s think about choosing a rubber gasket seal adhesive. What questions should you be asking before selecting one for your next application? Definitely these five!
1. How strong does the seal need to be?
When compared with tape, a seal made with a rubber gasket is stronger simply because the rubber is thicker and more durable so it can absorb more force being exerted on it. How much force exactly?
Well, each application is different. Yet, it’s clear that putting 1,000 psi of force on a small surface area is enough to test any adhesive. Likely, the adhesive for that application will fail before the rubber gasket due to the incredible amount of force.
That brings up surface area. If an application has a limited amount of space available on which to apply the adhesive, it magnifies the importance of the adhesive (a large surface has superior adhesion). One converted piece of rubber with the right adhesive can replace that same rubber with 25 screws if the surface area is large enough.
Some demanding applications may use mechanical fasteners and adhesives to increase the bond and prevent failure. For example, bolts may be used as a backup in case the adhesive fails. Conversely, an adhesive may simply do nothing more than hold the gasket in place until a mechanical fastener is added, making a solid seal.
Gaskets in Action (part I)
Have you noticed trucks on the highway that don't have any visible bolts on the side? That’s likely an adhesive tape/gasket creating a seal and eliminating the need for bolts or rivets.
2. What environmental factors will the gasket face?
Similar to how available surface area directly affects a bond’s holding power, the environment in which the rubber gasket seal performs is key. Exposure to high temperatures, pressure, and chemicals needs to be considered and tested.
Although rubber gaskets have been used in nearly any application imaginable (field testing is the ultimate test), a converter needs to send samples of any solution to a customer for trial. Application methods and conditions do vary, so testing is a must.
Gaskets in Action (part II)
Apply 40 pounds of pressure to ¼-inch foam rubber, compressing it to ⅛-inch, and it becomes waterproof. Compress it to 1/16-inch, and it handles pressure at 10,000-foot depths. Compress it to 1/32-inch, and its seal is tight enough for space travel. That’s how compression factor plays a role.
Gaskets in Action (part III)
In some applications, a rubber gasket will be compressed for a short time, and then released to return to its original shape. The material has to perform this over and over and needs to rebound each time. That’s how elasticity plays a role.
3. How long does the seal need to hold?
Not every type of adhesive is designed to hold for the same amount of time. Even different gasket applications have different requirements, from temporary to permanent and everything between.
Adhesives are generally classified based on their form: tape, film, liquid, paste, and solid. Published earlier this year, this article compares the two most popular, liquid and adhesive tape.
Rubber gasket seals, by the nature of the rubber, have high initial tack and hold, but they do not have a final hold as strong as acrylic, for instance. Your converting partner can review every possible option for your application.
4. What are the two substrates?
There are hundreds of converters that can flatbed die cut various shapes of rubber. The magic happens with the adhesive. But, that can’t be determined until the substrates are considered.
The substrates will ultimately determine which adhesives can be used, and the type of adhesives may or may not limit the material you use for the gasket. Some substrates, like metals, are not very picky when it comes to adhesives. However, low surface energy plastics have limited adhesives, and they do not behave well with all types of gasketing material.
3M™ VHB™, which falls under the umbrella of foam gasket (just as foam rubber gaskets do), is typically called VHB tape. Yet, it can function as a gasket — not a rubber gasket seal, however. VHB is brought up here to illustrate that two substrates can benefit from a bonding power of a solution 10 times stronger than rivets.
5. What is the application?
Yes, this blog post has been mentioning “applications” throughout, so why include it now? Because this is the most important question (and we’ve saved the best for last).
Some applications lend themselves best to rubber gaskets because of a converter’s ability to create the right solution. For instance, a very large and thin rectangle of rubber can be difficult to handle on its own. However, a converter can precisely die cut it and use a backing material to keep its shape until it’s put in place. At that point, a liner is removed, and the other matching part is applied, usually using automation to make it an exact fit.
The importance of automation should not be overlooked. Many converters can cut flatbed parts that then have to be applied by hand. The real value comes with engineering that creates a converted product that’s automation friendly and automation ready.
If you need custom gaskets, get in touch with Strouse today!