What Is a Silicone Rubber Heater?
A silicone rubber heater is a sheet-type heater made from silicone rubber materials.
Similar to ordinary nichrome wire heaters, their entire surface heats up when an electric current is applied. Sheets 2 mm or thinner are ideal for heating narrow or curved surfaces due to the flexibility of the rubber material. The sheet’s shape can also be customized to fit the object being heated.
The temperature setting can range from 60°C to about 300°C. These heaters are used for heating cylindrical containers and pipes as well as for heat sealing materials such as paper and plastic.
Uses of Silicone Rubber Heaters
Due to their flexibility and high thermal conductivity, silicone rubber heaters are utilized in various applications.
1. Automotive Field
In the automotive sector, they regulate battery temperature and heat car seats. They may also serve in defrosting systems. In cold climates or during winter, they can effectively control the temperature of engine oil.
2. Medical Field
In medicine, they keep medical equipment warm and are used for heat therapy. Devices for controlling blood temperature and heat therapy pads are examples. They also feature in incubators providing a warm environment for premature or ill infants.
3. Manufacturing Field
In manufacturing, they facilitate heating for various processes. Pre-treatment for welding and laminate heating are typical uses. Their low ignition risk and compact design also make them suitable for the aerospace industry, compared to nichrome wire heaters.
Principles of Silicone Rubber Heaters
Silicone rubber heaters consist of resistance wires layered at regular intervals between two silicone rubber sheets. The resistance wires are connected at both ends to lead wires extending from the silicone rubber heater, allowing for heating when voltage is applied.
The resistance wire is made from nichrome, a nickel alloy, or carbon. When electric current flows, resistance generates heat. Copper, known for its high electrical conductivity and flexibility, is the most common material for lead wires. This makes it easy to process and handle.
The heating capacity of silicone rubber heaters is defined by a metric known as watt density, which is the output wattage per unit area. Depending on the resistance wire’s heat generation and arrangement density, heaters with watt densities ranging from approximately 0.1 to 2 W/cm2 are available.
Types of Silicone Rubber Heaters
Depending on their application, silicone rubber heaters can be customized with holes, round shapes, or according to metal heating elements‘ design patterns.
1. Silicone Heater Pad (Square)
This common type is flexible and capable of producing uniform heat. It is suitable for flat surfaces or various forms, and used in piping, food processing, and chemical industries.
2. Silicone Heater Band
Designed for warming circular or cylindrical objects such as pipes and barrels, these bands wrap around the object to maintain the required temperature. Some models are also suitable for larger objects like drums and tanks.
How to Select a Silicone Rubber Heater
When choosing a silicone rubber heater, consider the installation conditions and required heat generation capacity.
1. Installation Conditions
Identify the object or process needing heating. Consider its thickness, shape, and size when selecting a heater. Also, choose a silicone rubber heater that offers durability and environmental resistance suitable for its intended environment.
2. Heat Generation Capacity
Manufacturers provide charts showing the heating capacity of silicone rubber heaters and temperature variation in air. Electrothermal calculations should be performed based on the desired heating temperature, time required to reach it, and the thermal conductivity of the object being heated. These calculations help determine the necessary heating capacity of the heater.
However, the achievable temperature of silicone rubber heaters can vary based on ambient temperature and how well they adhere to the heated object. A control system with a thermistor or controller may be required for precise temperature regulation.