They are especially designed for quick adaptation in molds or surfaces where the use of rivets either causes problems or impossibility to use. Cuadrawatt cartridges are the better choice. Cartridges with a low density of watts are most recommended for moderate heating up to a maximum temperatures of 300ºC. The square tube is made of prime quality stainless steel. All the tubes are perfectly calibrated both inside and outside, into which a long-life ceramic piece is inserted. The tube resists a continuous temperature variation and has the best possible thermal conductivity, as the ceramic piece is in contact with the wall of the tube, which makes the most perfect heat distribution possible.
Maxiwatt Model SC The heating wire is inside the ceramic piece. The nickel-chromium heater wire is of first-class quality and is the most recommended for the manufacturing of cartridge heaters due to its great tolerance to high temperatures. Everything is coated with checked magnesium oxide. The whole interior of the cartridge is also coated. Therefore, there is excellent conductivity between the heating wire and the object to be heated.
The most important element for ensuring the long life of the cartridge heater is the heating wire used in its manufacture. Maxiwatt uses the best to be found anywhere in the market. After extensive research and years of experience it has been shown that a heating wire made of Ni-Cr 80/20 is both efficient and resistant to the formation of metallic coating brought out by oxidation. As the austenitil combination of nickel and chromium lacks iron, it is the most recommended for the heating wire.
For the induction of electricity a nickel cable (sheathed by fiberglass) is used. It is coated with silicone and fire-proof glazing. The cable wires are turned. Sometimes, the charge of the cartridge prevents the use of this type of connection. Finally, special procedures are used: threaded outputs with bolts, opposite outputs, etc. The different types of connection are shown on protections section
Magnesium oxide is used for insulation, and is the most suitable for insulating the heating wire and the conductor lead against the current of the sheath of the cartridge. When the space between the heating wire and the protecting sheath is too short, an insulator is required, this should be composed of the best qualities: purity, high degree of thermal cartridge heater, maximum melting point, uniform and exact compression, perfect thermal conductivity, etc, so that the best isolation is obtained. Control of the working temperature is essential. It must never exceed the working limits of the cartridge. It is very important to store the cartridge in a dry space because magnesium oxide is very hygroscopic. Just a few drops of water particles are enough to weaken considerably the insulating capacity of magnesium oxide bolts, opposite outputs, etc. The different types of connection are shown on protections section.
The stainless steel 321 cover provides the highest quality for the manufacture of cartridge heaters. The materials which can be used in their manufacture are limited due to the strain caused by constant expansion due to the cooling and heating of the cartridge heater, the lack of a metal cover, which causes oxidation, and abrasive action. Stainless steel has been shown to be the most suitable material for the construction of cartridge heaters.
| Shealth material | Stainless steel 1.4541 |
|---|---|
| Heating conductor material | NiCr 8020 |
| Max. Shealth temperature | 750 ºC / 1380 ºF |
| Max. Voltage | 480 V |
| Wattage tolerance* | .+5% - 10% |
| High voltage resistance* | 1500 V AC at > 24 V operation voltage |
| 500 V at <= 24 V operation voltage | |
| Insulation resistance* | >= 5MW at 500 V DC |
| Leakage current | <= 0.5 mA at 253 V AC |
| Lenght tolerance | A 1.5%, min A 1mm |
| Standard diameter tolerance | metric -0.02 / -0.06 mm |
| inch: A 0.79 mils [A 0.02 mm] |
