Plastic Processing Heating Element of Cartridge Heater with Metal Screen Sleeve
Description:
A cartridge heater is a tube-shaped, heavy-duty, industrial joule heating element electrical
resistance used in the process heating industry, usually custom
manufactured to a specific watt density, based on its intended application. Highly
compacted they reach a surface watt density of up to 50 W/cm².
The cartridge heater may be divided in 7 main
parts:
Heating Coil; Insulation; Sheath; Sealing; Termination;
Lead Wire Type; Watt Density
Insulation is used to prevent the Nichrome coil
to contact the sheath. If such event happened, it would ground the resistance
and potentially produce a catastrophic short-circuit, resulting in a melted
sheath and a major equipment failure. Damage can be mitigated by installing a
ground fault interrupting circuit. To prevent the coil from touching the
sheath, the coil is inserted into the sheath, and immediately filled with Magnesium Oxide (MgO). To ensure the MgO fills the empty space between the sheath and the
coil, the cartridge heater is vibratory filled.
The sheath is the part of the cartridge heater
which makes contact with the material or substance to be heated. Several metal
alloys are used, depending on the type of application, such as highly acidic or
corrosive environments. The most common types of sheaths are 304 Stainless Steel, 316 Stainless
Steel, and Incoloy 800. Incoloy has the highest temperature rating, it is
considered a Superalloy.
After the cartridge heater has been filled with
MgO, a seal is applied to the open end of the cartridge heater (where the
Nicrome coil was introduced), this prevents the coil and the MgO from coming
out. Also, it prevents contamination, such as plastic debris, air, or moisture,
to go inside the heater.
Since cartridge heaters are installed in a wide
variety of machines, manufacturers must design the heaters to meet certain
clearances.The cartridge heaters might be terminated with the leads
coming out straight, or in a right angle. Also, manufacturer must be careful
that the leads are not exposed to temperatures higher than the maximum rating
for the lead wire. In order to prevent lead wire damage from temperature,
movement or contamination, the lead wire can be protected with metal conduit,
braided metal or silicone sleeves.
Depending on the clearance and the design of the
machine where the cartridge heater will be inserted, the type of wire used will
vary. Fiberglass is the commonly used for cartridge heaters and other high temperature
applications, such as automotive wiring harnesses and industrial equipment.
Other variants used are silicone impregnated fiber glass and silicone rubber.
Applications:
1. Seal Bars
2. Torpedo Heaters for injection molding
3. Injection molding manifolds
4. Mass Spectrometry
5. Rubber molding
6. Food production
7. Immersion Tank heating
8. HVAC Compressors
9. Fuel Cell
10. Semiconductor
11. Medical Devices
12. Sensor measurement devices
13. Extrusion
14. Die Casting
15. Hot melt adhesives
16. Heat Staking/ Hole Punch
17. Plastic welding
18. Fluid heating
