What Is a Cast-in Heater?
A cast-in heater is a type of heating device where a heater element is embedded into a cast material.
These heaters typically involve sheathed heaters and air-cooled tubes cast into materials like brass, aluminum, and iron. Cast-in heaters directly contact the object they are heating, using conduction heat for efficient energy transfer. They are known for their durability, resistance to overuse, shock, and vibration, and provide uniform heating of metal surfaces.
The design of cast-in heaters is versatile, allowing for temperature control through rapid or slow cooling by incorporating air- or water-cooled tubes. Rapid heating can be further enhanced by attaching heat-dissipating fins to the external surface.
They are commonly used in applications requiring high-precision temperature distribution, such as in plastic molding, synthetic fibers, semiconductor manufacturing, engineering plastics, or heating parts with complex shapes.
Uses of Cast-in Heaters
Due to their uniform temperature distribution and high corrosion resistance, cast-in heaters find applications in:
1. Appliances
Used in ovens, ranges, irons, electric pots, hot plates, electric kettles, etc.
2. Commercial Equipment
Used in ovens, electric furnaces, parts casting, press surface plates, air-conditioning and heating units, kitchen equipment, electric kilns, etc.
3. Industrial Equipment
Applied in tank heating, chemical heating, heat insulation, melting low-melting-point metals, injection molding machines, extrusion molding machines, valves, pipe insulation and heating, synthetic fiber production, semiconductor manufacturing, etc.
4. Drying Equipment
Used for drying foodstuffs, food waste, sludge, livestock products, paint, wood, etc.
5. Heating and Heat-Retention Equipment
Implemented in pipelines, storage tank pipes, valves, water pipes, drainage pipes for insulation, freeze protection, defrosting, semiconductor, and liquid crystal manufacturing, pharmaceutical production, medical and chemical equipment, melting and heating of metals like lead, solder, zinc, aluminum, medical equipment, optical equipment, etc.
Principle of Cast-in Heaters
Cast-in heaters integrate a sheathed heater into a casting material for uniform temperature distribution. They are less direct than other heating methods but are easier to manage, as there’s no need to drain liquid for maintenance.
The sheath materials for these heaters include STP, SUS, Incoloy, and Inconel, chosen based on usage conditions. The maximum surface temperature varies by material: approximately 350°C for aluminum, 500°C for brass, 600°C for stainless steel, and 800°C for iron cast-in heaters.
They are used for indirect heating in spaces where direct heat sources are impractical, such as due to flammability concerns or odors. The mounting surface of the heater is machined to enhance heat conduction.
Features of Cast-in Heaters
1. Highly Efficient Heating
Aluminum and brass used in cast-in heaters have high thermal conductivity and a large contact surface area, ensuring efficient and uniform heating.
2. Capable of Heating Complex Shapes
These heaters can accommodate valves and molds with complex shapes as the castings are produced from a mold, allowing for the heating of intricate designs.
3. Vibration- and Shock-Resistant with Long Service Life
The cast-in design offers excellent environmental resilience, vibration and shock resistance, and a long lifespan. They also have strong resistance to heat and moisture, and can be customized for specific applications like chemical and corrosion resistance.
4. High Power Density and Large Heating Area
They can be set to high power densities for intense heating, and their high thermal conductivity allows for heating large areas.
5. Easy Temperature Control
These heaters enable rapid and slow cooling through the use of air or water cooling tubes. Rapid heating is also facilitated by the installation of heat-dissipating fins.
Other Information on Cast-in Heaters
Improved Serviceability of Cast-in Heaters
Cartridge heaters inserted into machined holes in an aluminum plate can be replaced without detaching the plate, allowing for flexible temperature distribution adjustments by modifying the power and layout of the heaters.