INTRO: MgO cold cores are used to facilitate and customize the design characteristics of high watt density cartridge heaters. A cartridge heater design may be engineered to deliver power at a very narrow part of the overall heater, and the Cold core is used to complete the unheated part of the assembly.
The heated part of the cartridge heater is built on the MgO wind core, The conductor and/or thermocouples then follow the cold core out to the terminations. The cold core reacts to the swaging exactly like the wind core, allowing good electrical isolation and dimensional control.
MgO cold cores are very similar to the wind cores they compliment with respect to hole locations and dimensions. They are larger in diameter since they don’t have an area for heating wire and powder insulation on the periphery.
They require a proper combination of dimensional, material, physical, electrical, and microstructural properties. They are extruded into the final shape with no machining of dimensions except for length. The MgO grade is a high performance heater grade with optimum dielectric and insulation resistance properties. The grain structure must provide proper firing results for strength and dimensions, and proper compression reaction upon swaging.
Some customers simply use the existing spacer designs and extend the length for their application. These are typically the 4 groove, 4-tab, or 4-scallop design. This is certainly a viable option, but requires that the MgO backfill powder goes through the cold section as well. This can be an opportunity or a problem, depending on your logistics.
TATEHO OZARK also has a special composition in development, which is a highly porous variety. This may perform better in mechanical stability near the open end of the heater, and simplify or improve the manufacturing operations or product.
If you would like to participate in this emerging product, please contact us to discuss our grade XXTM.
It is not necessary to stipulate an TATEHO OZARK grade. TATEHO OZARK uses high quality electrical grade fused MgO from two North American sources. The minimum MgO content is 96.4% MgO with appropriate limits for impurities and magnetic iron.
For the purpose of finished part identification, TATEHO OZARK part naming will use the prefix “T”.
Your certification paperwork may indicate one of the above designations, which are used internally to specify and engineer the perfect MgO grind and blend for your part.
The following are typical analyses or limits for powders used to produce MgO wind cores. All raw materials are high quality fused grain powders which are processed in-house to obtain optimum particle size distributions for end use.