Dalton Weekly News Letter for 7-13-2018

One factor contributing to the life of a cartridge heater is the ability to pull the heat away

from the heater into the heat sink. We already start with a big advantage in that the split

sheath heater will expand and make contact with the walls of the bore for superior heat

transfer.  But if the heater is inserted into a bore in ceramic insulation, little heat moves

away from the heater and the heat build-up will cook the heater unless the watt density

is extremely low.

Thermal conductivity is the intensive property of a material that indicates its ability to

conduct heat.  Copper has an extremely high thermal conductivity and will literally

draw the heat away from the heater and distribute it quickly and evenly about its mass.

Aluminum is about half that of copper, but still extremely effective in drawing and

distributing heat.  Cast and wrought iron and mild carbon steel, commonly used in

tooling and platens are fair.   Worse yet, stainless steel is quite low in thermal conductivity.  

Higher watt densities can be tolerated by heat sink material with higher thermal

conductivity and, as the watt density climbs, the heat sink begins to factor in the

decision of tolerable or even warrantable wattage.  If watt density is high, give us

a call at Dalton and we’ll talk about the application..