TATEHOLABO

Sheath heaters are heaters with heating wires covered with metal pipes. It is a safe and secure electric heating component with low risk of electric leakage and electric shock.

They are widely used in household appliances such as coffee makers and electric kettles. Additionally, high-performance heaters are used in industrial equipment for mold heating and seal welding.

It mainly consists of a heating element (nichrome wire), a metal pipe, and an insulating material. The structure is as shown in the diagram below.Magnesium oxide is filled as an insulating material.

Magnesium oxide is used as a filler material because it is relatively inexpensive and has high thermal conductivity and insulation properties.

Measure the resistance between the terminals of the sheathed heater and inspect the heating wire for damage. Next, conduct an energization test by passing electricity between terminals to see how much heat is generated, and check for leakage current. Leakage current is the current that leaks out of the pipes when energized. The lower this current is, the safer the product. It is an important evaluation of sheath heaters. To measure the leakage current, the following circuit must be assembled to separate it from the current of energization.

We evaluate the flow rate and tap density of magnesium oxide powder used as an insulating material. Flow rate is a measure of fluidity and is expressed as the number of seconds it takes for a given amount of powder to pass through a hole. Good fluidity shortens the time required to manufacture heaters, thereby improving production efficiency. Tap density is a measure of fillability and is expressed as the density of the powder when it is packed in a container and subjected to vibration. Fillability is important because it affects heater performance. In general, higher fillability results in higher density inside the heater and better heater insulation performance. We have developed a tap & flow measuring device that realizes highly accurate and stable measurement, utilizing our accumulated know-how, and sell it to manufacturers of sheath heaters and others.