STF SEALING TECHNOLOGY
Tubular heating elements for variety of applications are subject to high temperatures as well as to rapid and frequent thermal transient states (on-off), which seriously put their integrity and long life to the test.
In order to manufacture reliable, safe and consistent heating elements for such extreme conditions, the raw materials used in the heating elements has to be selected and processed with an advanced knowledge and state of the art production technologies.
The sealing on the heating element has the function of preserving as much as possible the electric insulation properties between the coiled heating wire and the tube. The insulation properties are guaranteed by the high purity and correct drying of the magnesium oxide layer.
These critical points plays an important role to guarantee the safety and satisfactory usage of the heating element.
Any damage or degradation of the sealing causes the dielectric layer to progressively absorb humidity from the atmosphere, thus causing an increase in its electrical conductivity, the ensuing earthing of the phase being powered and the immediate shutting off of power supply because of the intervention of a safety switch.
The technology that we provide allows us to offer different sealing options for tubular heating elements such as silicon, epoxy, teflon, which are all equivalent in terms of international safety standards, but offering different guarantee periods regarding to phase-earth electrical insulation.
STF Sealing Technology is mainly used for the heating elements on cooking applications. For this technology, a conic cylinder with teflon material is pressed between the terminal pin and the sheath tube.
The teflon cylinder avoids the small pit which can hold humidity to effect magnesium oxide inside.
The graph indicates the significantly improved performance of the heating element against the humidity and absorption. The absorption of humidity is the main reason that cause the short circuit of the heating elements during the first ignition of the oven after long stocking time of the finished appliances.
STF sealing technology assures the heating elements to breathe by softening the sealing parts with heat in order to reach high performance and reliability during the life-time of the product.
This technology also increase the strength of the heating elements during the transportation, handling and assembly stages.