Posted on: 26 September 2016
Grommets help reinforce the edges of holes in materials, be they signs, machinery, or something else. Choosing a grommet is about more than strength, though; what you choose will affect the materials in and around the grommet. Rubber and metal are two of the most common materials you'll find for grommets, and the one you choose can affect your machinery or project greatly.
Fraying and Friction
Both rubber and metal grommets offer a type of protection against friction and fraying, but they differ on the source of the friction and fraying. If you're trying to protect the material passing through the grommet from friction from the grommet itself, then a smooth metal grommet is best. But if you're trying to protect the material that the grommet is in from fraying and friction, a rubber grommet is best. The sharper edges of a metal grommet can cut the material that the grommet is in.
One time when you want to avoid metal grommets, even if they will be smoother and less friction-inducing on the material passing through the grommets, is when you're passing electrical wiring through the grommet. Obviously, live electrical wires, poor insulation, and metal grommets is a bad mix. You're better off using rubber grommets and inspecting the wires' insulation regularly.
Vibration and Isolation
Rubber grommets provide a measure of vibration damping and isolation. This goes for both physical vibrations and acoustic sound waves. If you need to have a measure of separation between the material the grommet is in and the material passing through the grommet, rubber is absolutely the way to go.
Rubber is also better than metal if the grommet will be in hot situations. You can get rubber grommets that will withstand high heat; these will not transfer the heat like metal would. If the grommet will be in machinery that can get hot or will be out in the sun most of the time, rubber is a better material. This is also the case if the grommet will be somewhere where light could reflect off the grommet -- metal, of course, will reflect the light, possibly into your or someone else's eyes.
Rubber grommets can be very environmentally tough -- they won't rust, for example -- but they can crack or dry out depending on humidity, storage conditions, and so on. Talk to hardware and industrial supply dealers to find out the best way to store grommets so that you don't have to throw any out prematurely.Share