Four commonly used heaters for extruders and their advantages and disadvantages

1. Mica heating ring

The heating element is an electric heating wire or a flat electric heating wire (resistance strip). Mica sheets are used for the insulation layer. Use ordinary carbon steel swing plate to make a circular protective shell.

The advantages of mica heating coils are simple structure, easy replacement, and fast heating speed. The disadvantage is a shorter lifespan. This type was commonly used on early extruders.

The service life of mica heating coils is related to temperature. The higher the temperature, the shorter the lifespan. Mainly due to the poor heat dissipation ability of mica. The air gap formed between the heating coil casing and the machine is also a heat dissipation screen. So, besides the easy drying and burning of electric heating wires, the mica layer absorbs moisture after cooling, causing adjacent electric heating wires to arc and melt.

2. Cast aluminum heater

Cast aluminum heater is an effective way to utilize electric heating rods, which are bent into shapes according to specific requirements and cast into aluminum alloy to form a cast aluminum heater. In addition to the advantages of general resistance heaters, cast aluminum heaters can be made into a shape that fits well with the barrel, with a small air gap between them, which is conducive to heat conduction. Cast aluminum heaters have lower cost and longer lifespan than mica heating coils. The electric heating rod is tightly fixed inside the cast aluminum shell, improving the thermal conductivity performance. Enhanced the anti vibration, anti gasification, moisture-proof, and explosion-proof characteristics of the electric heating wire. For occasions that require cooling, cooling coils can be intermittently cast into the cast aluminum heater. Therefore, this type of heater has been widely used.

3. Aluminum shell heater

The aluminum shell heater uses a straight electric heating rod as the heating element, which is inserted into the aluminum shell hole. After the electric heating rod is damaged, it can be replaced individually, reducing maintenance costs. The drawback is that the heat transfer and vibration resistance performance are not as good as that of cast aluminum heaters.

4. Ceramic heater

The electric heating wire heater, which uses ceramic blocks instead of mica as insulation material, has the advantages of fast heating speed, long service life, low price, easy replacement and adjustment of heater capacity. It is increasingly favored and used by manufacturers of PE coil extruders and other extruders.