Upgrading Old Plastic Machines with Induction Heating — Step-by-Step Guide

In the plastic processing industry, the heating systems of a large number of old extruders, injection molding machines, film blowing machines, and pelletizing machines still in operation generally adopt traditional resistance wire heating coils, cast aluminum heaters, or ceramic heating coils. Although the structure is simple, the high energy consumption, slow temperature rise, and large temperature fluctuations make it difficult for production efficiency and energy efficiency to meet modern manufacturing requirements.

As induction heating technology matures, more and more enterprises are choosing to retrofit old plastic machines with electromagnetic heating devices. This not only achieves energy savings of 30% - 70% but also significantly improves production volume and product stability. This article provides a complete and practical retrofit procedure guide to help factories quickly complete the upgrade and retrofit.

I. Why upgrade old machines to electromagnetic heating?

Before the formal retrofit, understanding the value of the retrofit helps enterprises make quick decisions.

1. Remarkable energy - saving effect

The energy efficiency of traditional resistance heating is about 50% - 60%.

The energy efficiency of electromagnetic induction heating can reach over 90%, and the energy - saving range is generally 30% - 70%.

2. The temperature rise speed is increased by 2 - 3 times

Induction heating can directly heat the inside of the feeding cylinder in a short time, greatly reducing the pre - heating time at startup.

3. More stable temperature

The temperature control accuracy is high, the material melts more uniformly, and the product quality is more stable.

4. Lower the outer shell temperature and factory environment temperature

After the retrofit, the surface temperature of the feeding cylinder can be reduced from 120°C to 40°C - 60°C, and the working environment is obviously improved.

5. Extend the service life of the heating coil and reduce maintenance

The induction coil is non - contact with the feeding cylinder and will not burn out repeatedly like traditional heating coils.

II. Pre - retrofit preparation and inspection

Before starting the project, the following inspections are necessary.

1. Confirm the number of heating segments of the machine

For example, an extruder generally has 4 - 8 segments, and each segment corresponds to one induction heater.

2. Measure the diameter and length of the feeding cylinder

To select a coil and insulation material of sufficient size.

3. Confirm the power supply conditions

Whether the voltage is three - phase 380V (common in China)

Whether the power of each heater matches the switchboard capacity

It is necessary to ensure that the safety level of the wiring meets industrial standards.

4. Keep the original temperature control system

The retrofit of the induction heater is generally compatible with the original temperature control table. Just ensure the following:

The thermocouple is normal.

The temperature control instrument can output a relay signal.

5. Confirm whether the on - site space allows installation

The following must be ensured:

There is sufficient winding space for the coil.

The insulation layer can completely cover it.

The control panel and cables are reasonably arranged.

III. Standard process for retrofitting old plastic machines to electromagnetic heating

The following procedures are applicable to common plastic machines such as extruders, injection molding machines, and pelletizing production lines.

Procedure 1: Remove the old heating coil and cast aluminum heater

Turn off the power and confirm safety.

Remove the old heating coil, resistance wire, and ceramic coil.

Clean the remaining rubber, oil stains, and rust on the surface of the feeding cylinder.

Keep the temperature control system and thermocouple.

Procedure 2: Cover with insulation material (20 - 30mm)

Evenly wrap the outer layer of the feeding cylinder with:

Nano - insulation cotton

High - temperature - resistant layer of glass fiber cloth

Functions:

Prevent heat leakage.

Improve the energy - saving effect.

Protect the electromagnetic coil from direct contact with high - temperature metal.

Procedure 3: Wind the electromagnetic heating coil

Wind it professionally according to the length and diameter of the feeding cylinder:

The coil spacing must be uniform.

The coils must not overlap.

The winding directions must be consistent.

The winding quality directly affects the induction efficiency and stability.

Procedure 4: Install the electromagnetic heating controller

Usually, one is installed for each feeding cylinder segment.

Connect to the three - phase power supply.

Connect the control end to the output of the original temperature control table.

Connect the coil output end.

Confirm good grounding.

The controller generally has the following functions:

Over - current protection

Over - temperature protection

Phase - loss protection

Automatic power adjustment

Procedure 5: Overall inspection and adjustment

The adjustment procedures are as follows:

1. Confirm that all wiring terminals are firmly fixed.

2. Confirm that the coil is in full contact with the insulation layer.

3. Set the temperature of the corresponding temperature zone.

4. Test the temperature rise speed with an empty machine.

5. Check for abnormal sounds, overheating, or alarms.

6. Put in materials and start the trial operation.

Normally, the temperature of the heating cylinder can reach the set value in 10 - 15 minutes.

IV. What practical effects can be obtained after the retrofit?

Enterprises are most concerned about the following points:

1. Actual measurement of energy - saving data: 30% - 70% power savings

For example:

Model 75 extruder

Before retrofit: 210 kWh/day

After retrofit: 125 kWh/day

Save 85 kWh per day

Save over $10,000 in electricity costs per year (converted value)

2. The production capacity is improved by about 10% - 20%

The temperature rises quickly, the temperature control is stable, and the screw plasticizes more fully.

3. The maintenance cost is significantly reduced

The service life of the electromagnetic coil is more than 2 - 3 times that of the traditional heating coil.

4. The factory temperature is reduced by about 10°C - 20°C

The working environment of employees is improved.

V. Conclusion: The optimal energy - saving solution for upgrading old plastic machines

Induction heating retrofit has become a standard solution for energy - saving upgrades in the plastic processing industry.

It not only reduces energy consumption, increases production volume, improves quality, and reduces maintenance but also breathes new life into equipment that is more than a decade old.

For factories aiming to reduce costs and improve competitiveness, retrofitting old plastic machines to induction heating is one of the investments with the highest return rates.