Silicone rubber heaters from Sinomas make it possible to achieve very flexible and reliable heating solutions. Flexible not only represents the physical property of the products, but also the choices you have for the silicone rubber heater design. You can get fully customized silicone heaters where you can specify the supply voltage, the wattage, the dimension or even 3D geometry, the means of installation, the thermal insulation, temperature control method, etc. Your devices will be heated accurately in the pattern as you desire.
Silicone rubber heater can be made with etched foil heating elements or wire wound heating elements.
Wire wound elements are wired manually according to certain patterns. The productivity and wiring accuracy highly depend on the skill of the workers, especially for small sized heaters. Unless for irregular shaped 3D profiles or long heating tapes, wire wound technology has been phased out at Sinomas.
Etched foil silicone rubber heaters make use of thin metal foils (0.05mm), usually nickel based alloy, as the resistance element. The resistance pattern to be etched is designed in CAD and transferred to the foil, which is laminated to the insulation substrate. The element substrate is then processed through acid solution to produce the desired resistance pattern.
Low voltage heaters often mean low ohm value. Very thin copper foil will be used in these cases. The operation temperature should not be very high, e.g. below 100°C. Otherwise the copper foil may burn out over time.
The etched foil silicone rubber heater has exceptional heat transfer compared to wire wound elements, due to its large flat surface area. It can deliver more uniform heat profiles with higher watt density, providing longer service time. It can also be zoned with variable wattage or separate heating circuits to accommodate load variations. Edge compensation for more even temperature distribution can also be achieved.
Dual Voltage and Three Phase Pad Heaters
Due to the flexibility in circuit design of etched foil heating element, multiple circuits can be designed to accommodate dual voltage supply (same watts output) and multiple heat zones. On dual voltage pad heaters, three leads, including a common in a different color, are provided for wiring the heaters in series for the higher voltage and parallel for the lower voltage. 12V 24V (DC) and 120V 240V (AC) are most popular combinations. Multiple circuit areas can be zoned to achieve different heat profiles. Three phase circuits can also be designed for high current applications.
These options and advantages also apply to our kapton heaters.
Non-magnetic Silicone Heater
For special applications that are sensitive to interference of magnetic filed, the silicone heaters are required to emit no magnetic field. This can be achieved by selection of proper resistance foil material and smartly designed circuit. Stainless steel foils can be laminated on top of the heater to further eliminate the magnetic effect. Typical examples are the heating for MRI scanners and some military airport electronics.
Specification of Silicone Rubber Heaters
|Electrical Characteristics||Thermal Characteristics|
|Voltage rating: 0-480V, AC or DC||Max operation temperature: 250°C|
|Watt density: ≤ 5.0W/cm2||Continuous operation temperature: ≤200°C|
|Watt tolerance: ±5%||Temperature control: per requirement|
|Insulation resistance: >500M||Minimum size: 10mm x 25mm|
|Dielectric strength: 1500V/min||Maximum size: 800mm x 3000mm|
|Ground mesh: per requirement||Lead type: Teflon cable, silicone cable, PI cable, with different terminations|
|Mean lifetime: ≥100,000 hours||Thermal insulation: silicone sponge of different thickness|
Factory vulcanization of the silicone rubber heaters is recommended for the following permanent installations:
- heaters to be installed inside or outside of a drum, e.g. heated roller for X-ray photograph processing
- heaters to be installed on complicate shaped objects, like bent or T pipes
- applications which have high requirement on temperature distribution
With our special developed tools, the silicone rubber heaters can be pre-formed to a certain shape and easily attached to your equipment without extra work. Minimum temperature variation will be ensured. A good example is the heating sleeve for thermal transfer heat press.
We deliver many silicone rubber heaters factory vulcanized with black anodized Aluminum plates as cabinet heater for high voltage switchgears.
Temperature Rise Curve
The figure below illustrates the surface temperature of 1.5mm thick silicone rubber heaters with different watt density over time. The sample (square shaped silicone pad heater ) is hanged vertically in 20°C free air. The data is supposed to be a reference for 1.5mm thick silicone rubber heater of standard structure. This is to give you an idea how fast the heating can be at different watt densities.