® Cartridge Heater allows

　　The unique split-sheath design of the Watt-Flex

　　the independent, bilateral expansion of each half of the heater outward

　　against the walls of the surrounding bore. Maximized metal-to-metal contact

　　results in greatly improved heat transfer under normal fit conditions of .005"

　　to .007". The thermal expansion of conventional cartridge heaters limits

　　heater contact to only one side of the bore (Figure 1). The unique split-sheath

　　expansion of Watt-Flex heaters assures superior heat transfer, more uniform

　　process heat, greater efficiency, and reduced consumption of electricity.

　　Unlike conventional cartridge heaters, Watt-Flex heaters have a continuous

　　heating coil for a more uniform temperature profile. Continuous coil construction

　　eliminates the cold spots which can occur at core junctions in

　　ceramic core heaters. (See Figure 3.) With Watt-Flex heaters there are no

　　independent sections to burn out. Therefore, Watt-Flex heaters are either

　　totally on or totally off. Figure 4 shows the superior temperature profile

　　along the length of a torpedo probe heated by a Watt-Flex heater. Uniform

　　sheath temperature is vital when molding heat-sensitive plastics where the

　　temperature window between gate freeze-off and material degradation is

　　very narrow.

　　By varying the watt-density, the temperature profile may be custommatched

　　to specific requirements. For example, certain applications, such as

　　those requiring temperatures higher at the tip of a molding probe than along

　　the sheath, can be accomplished with Watt-Flex heaters but not with conventional

　　cartridge heaters.

　　The Watt-Flex Cartridge Heater is essentially a tubular heater bent back

　　on itself and swaged into a cylindrical format. Unlike conventional heaters,

　　Watt-Flex heaters have no ceramic core which can crack during swaging,

　　therefore, they can be compacted to a much greater density. This process

　　increases both heat transfer ability and insulative value of the dielectric.

　　The greater insulation value accommodates significantly higher wattdensities.

　　In fact, Watt-Flex heaters produce up to 50% higher warrantable

　　watt-densities than conventional heaters and can operate at much higher

　　temperatures.

　　The life of a cartridge heater is directly related to its internal operating

　　temperature. Denser and more uniform compaction of the dielectric provides

　　greater heat transfer to the Watt-Flex sheath. This, combined with more efficient

　　heat transfer to the surrounding metal through intimate contact with

　　the wall of the bore, permits the Watt-Flex resistance coil to run substantially

　　cooler than conventional cartridge heater coils. The result is up to five times

　　longer life, decreased downtime, and lower operating costs.quot;

　　Watt-Flex heaters have no ceramic core which can crack during swaging,/pp align=/p