Silicone heating pads consist of a metal heating element, attached to coated power leads, between two thin sheets of silicone rubber. Silicone rubber is tough, light, and thin ― usually 2 or 3 millimeters thick ― and its lack of reactivity makes it resistant to moisture and chemicals. Low thermal mass and superb electrical insulation allow silicone heaters a high power density and rapid reactions to temperature controllers. Silicone heaters are efficient at heat transfer and designed to tight tolerances, and they can operate in temperatures down to -76°F and up to 446°F.
Silicone heating pads can be manufactured for a wide variety of wattages, amperages, and power densities, for gentle or intense heat. They can be cut to almost any shape, including irregular shapes, three-dimensional shapes, and shapes with holes.
Thermostats can be attached directly to silicone heating pads, temporarily or permanently. Thermal fuses can also be added to prevent overheating if the primary control device fails.
Silicone heating pads can be mounted with straps, snapped or clamped to cylindrical parts, attached with adhesive, temporarily mounted with magnets, or permanently vulcanized to parts in the factory.
Heating Elements: Wire Wound or Etched Foil?
Silicone heating pads are available with two different types of heating element that have different advantages: wire wound or etched foil.
Wire wound pads, which use thin, spaced-out resistance wires wrapped around fiberglass supports, are best for unusually shaped pads. They are durable, and thus well-suited to heaters that will frequently need to be removed and reinstalled. They can be manufactured quickly and cheaply with no tooling, so they are ideal for low-volume projects and prototypes.
Etched foil pads use a chemically etched sheet of foil. They heat more quickly and have an even greater power density and better heat transfer; their heat is more uniform and their operating life longer. However, they are more susceptible to damage from repeated bending. They require a tooling cost up front but have a more heavily automated manufacturing process, making them more cost-effective for high-volume projects.
Common applications for silicone heating pads include:
- Telecommunications equipment
- 3D printing
- Aerospace manufacturing
- Food processing and storage
- Many other industrial uses
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