Spilt sheath cartridge heaters are tubular heaters that formed in to a half circle which is then folded in the middle with the two halves now making a circle. Their claim to fame is that they are easier to remove from a hole.
The two halves expanding as the heater heats up with the heater more completely filling the hole. The amount of expansion is actually a function of the thermal expansion of the metal sheath. Different metals expand different amounts, but all of the expansions are rather small, at least compared to the drawings, which are exaggerated for clarity. All of the sheath materials are either one of the stainless steels or incoloy steel.
The efficiency and life expectancy of a split sheath cartridge heater depends mainly on the fit tolerance. Cartridge heaters are typically manufactured .003" to .005" smaller than the nominal diameter. Drilled holes are typically .001 to .003 larger than the nominal diameter. Inserting a cartridge heater with a nominal minus of .005" into a drilled hole with a nominal plus of .003" results in a fit tolerance of .008". Although a tighter fit is desirable to efficiently transfer heat and to get long heater life, a looser fit will help in installing and removing long heaters. We therefore recommend split-sheath cartridge heaters.
A "loose" fit condition of .008" may be acceptable for:
1. low watt density at higher temperatures.
2. higher watt density at lower temperatures.
Besides the heater, you need to consider also:
• Temperature sensor
• Temperature controller
• Electrical power switching.
Cartridge heaters are most frequently used for heating metal parts by insertion into drilled holes. For easy installation, the heaters are made slightly undersize relative to their nominal diameter.
Cartridge heaters can be easily specified to meet the demands of special applications. Simply select from a variety of standard options and features to customize the heater to your specific needs. For customized engineering or alternative options, contact Jaye’s sales representative for fast turnaround on your specifications.
• Lead wire Types
• End Seal Options
• Lead Options
• Mounting Options
• Built-In Thermocouple