Cartridge Heaters are commonly used to heat metal parts through insertion into a drilled (and reamed) hole. For simple installation, cartridge heaters are manufactured slightly undersized relative to their nominal diameter. To ensure you get the maximum heater life, it is recommended to use the least possible wattage while still satisfying the requirements of your application.
Cartridge Heaters insertion holes should be drilled and then reamed to the final diameter to ensure the hole is as accurate as possible. A tight fit is very important as this will ensure you get the maximum heater life. At higher watt densities, this becomes even more important and will prevent heaters from burning out to fast.
*Heater Fit = (Maximum Diameter of Hole) – (Minimum Diameter of the Heater)
The smaller the Heater Fit the better.
Non-Swaged Cartridge Heaters are a cheaper alternative to standard swaged cartridge heaters and can be used in applications where high watt densities are not required. Non-swaged cartridge heaters can be used at watt densities of up to 45 watts/in2 and temperatures up to 1000°F.
One benefit of Non-Swaged Cartridge Heaters is that they have tighter length tolerances than swaged heaters. They can also be constructed with 3 independent heat zones.
Non-Swaged Cartridge Heaters are not recommended for applications with lots of vibration or impact as this will result in early failures.
MPI also offers Square Cartridge Heaters for applications where a drilled hole is not practical. Our square cartridge heaters are swaged, which makes these heaters capable of handling high temperatures and high watt density.
A key benefit of Square Cartridge Heaters is that they are much easier to remove from a slot after extended high temperature usage compared to the removal of a round cartridge heater from a drilled hole. Square Cartridge Heaters are also good for milled slots in long platens where drilling a hole would be too hard.