Cartridge heaters

Tempco’s high-density cartridge heaters are used all over the world to improve a diverse range of applications where high quality and a long service life play a significant role. The internal resistance wire temperature is a crucial factor for the unit’s service life and higher temperatures require a lower watt density to prevent damage. Watt density, the power per unit area of the sheath, must be carefully matched to the application. Although higher watt densities can be more efficient, they can also shorten the service life if limits are exceeded.

A tight fit between the heater and the drilled hole plays an important role in improving heat transfer. For high-temperature or high-watt density applications, the use of reamed holes is recommended. Additionally, the position of the temperature sensor is of great importance. A sensor placed close to the heater minimises thermal deviations and prevents overheating. The use of precise power and temperature controllers, such as PID controllers, also contributes to better control and a longer heater service life.

To reduce temperature fluctuations, we advise using modern power controllers such as SCRs. This reduces oxidation and thermal stress on the heating element. Contaminants such as moisture, oil and molten plastic are a common problem and can penetrate through the heater’s seal. Using special seals, such as epoxy or Teflon®, can limit this effect.

Furthermore, excessive bending of the leads and a lack of heat dissipation can lead to premature failure. Adding strain reliefs and cold sections in the design can prevent these issues. To optimise performance, the use of anti-seize coatings such as Tempco’s BNS spray is recommended. This not only facilitates heat transfer but also makes the removal of the heaters easier.

Following these guidelines significantly extends the service life of the heaters and optimal performance can be guaranteed.