Why use a heating rod to heat the extruder barrel? Plastic extruder barrel heater

In the plastic industry, the plastic extruder barrel heater and plastic extrusion require heating and insulation of the extruder screw. There are differences in heating methods among single screw extruders, twin-screw extruders, and triple screw extruders.

Single screw barrel heating

Common methods include ceramic heating, infrared heating, aluminum casting heating, etc. For extruder manufacturers, ceramic heating is simple to operate, low in price, and has the highest acceptance.

Three-screw barrel heating

The function of the three screw is mainly suitable for high filling, especially PP, PE+80% CaCO3

Due to the pursuit of production capacity in filling masterbatch, the sales price of masterbatch is not high, so a simple and low-cost cylinder heating method is needed.

So cast aluminum heaters are the best choice, followed by cast copper.

Of course, heating rods can be chosen, but the cost is higher than that of cast copper heaters. Just for the production of filling masterbatch, there is a bit of wasted cost.

Twin screw barrel heater

Choose different heaters for different materials:

The PP PE market has a high demand, so cast aluminum heaters are the best choice

It is recommended to choose copper casting heaters for PLA, PET, and other materials, as they are sensitive to temperature control, and copper has good thermal conductivity.

PEEK, PEI, PA, PETG, PPSU, and other high-performance materials are the best choices for heating rods.

 

The difference between traditional heaters and heating rods

• The traditional heater (cast copper and cast aluminum heater) has a clamp plate structure and is divided into two heating plates, upper and lower.
• Its interior is made of resistance wire, cast aluminum/copper shaping, and finally CNC-machined. Finally, add a layer of a stainless steel protective plate externally.

• The heating rod is made of high-temperature alloy casting, with an internal heating resistor connected by a high-temperature nickel-based alloy power cord.
• It is worth noting that using a heating rod requires high-precision processing of the cylinder in advance.
• During the cylinder processing, it is necessary to bypass the cooling water channel.
• The opening requires accurate calculation, thermal expansion, a diameter 0.1mm larger than the size of the heating rod, and a surface smoothness Ra ≤ 0.4.So the price of the heating rod cylinder is about 20% higher than that of a regular barrel.

 

Comparison between the heating rod and the heating plate

Cast copper and cast aluminum heating plate:

1. The price is cheap enough to handle the processing of ordinary plastics
2. High market share

Heating rod:

1. High temperature limit, 400~500 ℃, is very simple and stable. Our heating limit is 600 ℃, and if a higher temperature is required, we can open the settings.
2. Each zone has 6-8 heating rods, and if one of them is damaged due to aging, it will not affect the heating in that zone. Moreover, the temperature is still accurate and can continue to work without stopping the machine.
3. Internal heating with fast heating speed and slow temperature loss, resulting in better insulation and energy savings of about 15% compared to cast copper heaters
4. Accurate temperature control, low temperature delay, delay time of about 30s

 

The disadvantages of both

Heating plate: 

1 After a long period of aging, the gap between the clamping plate and the barrel becomes larger, and the temperature control is not precise, which affects plastic processing.

2 If the temperature is too high due to prolonged use or worker error, it will deform when heated.

Heating rod:

1. Slow processing and production cycle.

2 The hardware and system for heating are 15-25% more expensive than heating plate heaters, so heating rods are particularly suitable for high-temperature special materials with high material value and precise temperature control (such as PEEK, which is strongly recommended and even requires the use of heating rods)