The different types of cartridge heaters depend on the type of applications, maximum temperature, overall length, watt density, tube diameter, heated length, and the variety of heating element being used. These factors help in determining the type of cartridge heater as well as how it is intended to be used.
The fundamental construction of most of the cartridge heaters is exactly the same regarding casing, wiring, and core. Variations will be observed in the kinds of metals, cores, and wires used. The durability and the associated quality of a cartridge heater is mostly dependent on the kind of materials that are used to manufacture it.
Cartridge Heater Types
1. Thermocouple Cartridge Heaters
Cartridge heaters that have a built-in thermocouple are utilised in heating the surface directly and their construction makes use of complex formulas to determine the fit, density, and wattage. The sheath temperature is measured by the internal thermocouple to determine the process temperature; internal thermocouple is ideal when there is a limitation in terms of available space. The sensor and power leads of the thermocouple are placed together on the outer side of the sheath. There are different varieties of thermocouple cartridge heaters, and they have been designed for specific applications. The thermocouple can be attached to the centre of the core, or at points along the length of the heater, or at the end of the heater. Based on the placement of the thermocouple, 3 styles of thermocouple cartridge heaters are available.
2. Flanged Cartridge Heaters
Cartridge heaters that have flanges make it possible to attach these kinds of cartridge heaters to the piece that is going to be heated. This is done by making use of a flange that is fixed permanently to the cartridge heater’s exterior end. This is done in order to make sure that the heater fits securely.
3. Swaged Cartridge Heaters
Prior to the swaging process, all of the elements including the oxide powder, resistance wiring, and the core are added to the heater. Mechanical swaging pushes the heater through a die thus reducing its diameter and also compacting the interior components. This compacting process improves efficiency and enhances the heat transfer process.
4. Multizone Cartridge Heaters
When it comes to multi-zone cartridge heaters, a wound coil and power leads become an individual part of each and every section of the heater. There are two leads for every zone. In certain types of configurations, it is designed such that the zones will just have a common wire, and this would in turn act as one of the leads; the individual sections can thus be controlled through this design. The advantage that the multi-zone system brings is that it gives us the ability to switch off a zone when it is not required; this in turn reduces the energy required.
5. Cartridge Heaters with Threaded Fittings
These types generally function similar to a flanged cartridge heater, threaded fittings help in providing the surety that the cartridge heater has been fit thoroughly. Threaded fittings give the luxury of faster installation and even speedy removal. Through the use of moisture seals protection enhancement is achieved.
6. Cartridge Heaters with Split Sheath
Split sheath cartridge heater’s sheath is capable of expanding to increase its contact with the walls of the bore; this ensures maximum heat transfer and subsequently lesser power consumption.
The expansion of the sheath is achieved by eliminating the heater’s ceramic core, and in turn replacing it with magnesium oxide (MgO) that’s tightly packed around the heater coil. In doing so, the heater’s dielectric strength sees an improvement, and also better heat transfer is achieved. Split sheath cartridge heaters by nature of its construction have improved durability and have lesser failures that are the result of a bore seizure.
7. High Density Cartridge Heaters
High density cartridge heaters spread heat evenly over the casing of the heater and offer extraordinary power. They are built in order to withstand tough and rugged working conditions like expansion and contraction, vibrations, high temperatures, and shocks. Standard high density cartridge heaters have a cylindrical ceramic core around which a resistance wire is tightly wound. Room for more than one power zone is made available in a high density cartridge heater through the manner in which the resistance wire is placed.
8. High Temperature Cartridge Heaters
These kinds of cartridge heaters are designed with the goal of being able to withstand use in applications that involve very high temperatures; temperatures may range between 760°C and 870°C. Generally a lot of cartridge heaters that are used in high temperature applications are swagged, so that there is maximum vibration resistance and heat transfer. These types of cartridges are often used for sealing bars, hot stamping, heating platens, heat staking, and forming.
With over 3 decades of expertise in temperature sensor and cartridge heater manufacturing, Heatcon Sensors provides a high level of quality, accuracy, and an unbeatable commitment to customer support.