Rubber grommets are rubber rings that can be placed around an opening in a surface. Grommets are used to protect surface openings from tearing or breaking, and they protect objects that pass through the openings.
For example, rubber grommets are often used to protect wires or cords that pass though openings in metal surfaces that would otherwise be too jagged or sharp.
Rubber grommets are used to protect other objects. The plastic or rubber insulation around electrical cables is particularly vulnerable to abrasion or to breaking after repeated flexing at its point of entry through a surface.
Some wiring varieties are vulnerable to damage if exposed to thin, hard surfaces because of the risk of crimping. Rubber grommets that protect wiring are usually broad and round, which prevents thin wiring from becoming crimped at an angle.
In industrial settings, many kinds of machinery and control equipment are housed in punched sheet metal; wire entry points in punched sheet metal are often fitted with rubber grommets to protect wires from becoming damaged.
Many factories and warehouses are equipped with ceiling-suspended, retractable power outlets. After repeated pulling and movement, power cables can become damaged or disconnected if not properly secured. Rubber grommets can be used in this situation to snugly hold wires at their point of contact to avoid damage to connection points.
Rubber grommets are usually made of extruded rubber, though they can also be molded rubber. Rubber extrusion is the process by which raw rubber is forced through equipment that heats and pressurizes it. Once the rubber becomes molten, it is forced through a die, which is a tool designed to shape raw materials into usable products. When the rubber emerges on the other side of the die, it is allowed to cool and harden, at which point it is cut and becomes a finished grommet.
Extrusion is not always a suitable grommet fabrication process, though, as it can only produce very simple shapes. Injection and compression molding processes can produce more complicated shapes. Both processes begin the same way as extrusion; the rubber is heated to a molten state.
Rather than using a die, though, molding processes involve the injection of molten rubber into a cavity. Once forced into a cavity, molten rubber conforms to the contours of the cavity.
Compression molding provides compressive force to the rubber which ensures that the rubber will come into complete contact with the cavity’s surfaces. After the molding is complete, the rubber is ejected from the mold, and it is allowed to cool and harden.
The product is then cleansed of imperfections if necessary and sent for shipment or additional processing.
Rubber Grommets Informational Video