---
title: "Replacing heater bands on an injection molding machine"
url: "https://www.imspares.com/injection-molding-machine-parts/heaters/replacing-heater-bands/"
---

# Replacing heater bands on an injection molding machine

How to find a failed heater band on an injection molding machine, remove it with a heater band removal tool, fit and tighten the new band, and check the zone.

Heater band replacement on an injection molding machine means isolating the zone, finding the failed band, loosening its clamp bolt, removing it from the barrel, cleaning the barrel surface and clamping a new band of the same size, power and voltage in its place. The clamp bolt, highlighted in the drawing, is the part that matters most: a band only works when it is tightened firmly and evenly against a clean barrel. When burnt plastic holds a band in place, a heater band removal tool helps free it without damage.

## Before you start

Heater bands run on mains voltage and sit on a hot barrel. Follow your site's lockout procedure and the machine manual.

- Switch off and **lock off the heater supply**, and check the terminals are dead before touching them.
- Let the barrel cool to a safe handling temperature, or follow your site's procedure if bands are changed warm. Wear heat-resistant gloves and eye protection.
- Retract the injection unit and keep clear of the nozzle; plastic in the barrel can still be molten.
- Have the replacement ready: same inside diameter, width, power, voltage and connection. See [heater band types](https://www.imspares.com/injection-molding-machine-parts/heaters/heater-band-types/).

## Finding the failed band

1. On the temperature screen, find the zone that heats slowly or not at all while its output is high.
2. With the heaters on, check each band of that zone with a clamp meter on its cable. A band that draws no current while the output is on has failed or is not connected.
3. Isolate and lock off. Measure each band's resistance at its terminals. Compare with the value expected from its rating, R = V² / P. An open circuit means a broken element.
4. Test the insulation resistance between each terminal and the band's shell. A low reading means the band leaks to earth and will trip the earth leakage protection.
5. Look at the band: burnt terminals, a swollen or cracked shell, or plastic underneath.

If the bands are good, look at the cable, the fuse, the relay and the thermocouple instead; see [temperature control](https://www.imspares.com/injection-molding-machine-parts/heaters/temperature-control/).

## Removing the old band

1. Photograph the wiring and note which terminal each cable goes to and which zone the band belongs to.
2. Open the terminal box and disconnect the cables.
3. Remove the thermocouple if it passes through the band or sits next to it, so it is not bent or pulled. See the [thermocouple guide](https://www.imspares.com/injection-molding-machine-parts/heaters/thermocouple/).
4. Loosen and remove the clamp bolt or bolts. Two-piece bands have a clamp on each side.
5. Open the band at its gap and lift it off the barrel. Do not lever it with a screwdriver against the barrel or bend the shell sharply.
6. If burnt plastic holds the band, warming the zone softens it. A [heater band removal tool](https://www.imspares.com/parts/mc-gmp-02/) helps free a stuck band without damaging it, and protects the band and its thermocouple connections when you remove and refit a band you are keeping.

## Preparing the barrel

The new band transfers heat by contact, so the surface under it must be clean.

- Remove burnt plastic, scale and old residue from the barrel surface without scoring it.
- Find and fix the source of any plastic under the band, usually a leak at the nozzle or the barrel front flange. Otherwise the new band will fail the same way.
- Check the thermocouple hole is clear.

## Fitting the new band

1. Check the new band's label against the old one: inside diameter, width, power and voltage.
2. Open the band only as far as needed to slide it over the barrel, and place it in the same position as the old one, with the thermocouple hole aligned if it has one.
3. Turn it so the terminal box is accessible and the cable will not touch the barrel or moving parts.
4. Tighten the clamp bolt evenly until the band sits tight all around, without distorting the shell. On two-piece bands, tighten both sides a little at a time so the gaps stay even.
5. Reconnect the cables to the same terminals, using heat-resistant cable and terminals in good condition, and close the terminal box.
6. Refit the thermocouple fully into its hole.
7. Before switching on, measure the band's resistance and insulation once more.

## After the first heat-up

1. Heat the zone and check that it heats and that its reading responds.
2. When it has reached temperature, re-tighten the clamp bolt, following your site's procedure for working near hot parts. New bands settle and expand on their first heat-up.
3. Compare the zone's reading with a handheld probe, and watch its output percentage over the next cycles.
4. If the zone overshoots or swings, run the controller's auto-tuning as described in the machine manual.

## Why bands fail, and how to make the new one last

- **Loose clamp.** The air gap makes the element run hot. Check clamps at planned stops.
- **Plastic under the band.** Fix leaks quickly and keep purged material away from the bands.
- **Wrong voltage.** A band rated for a lower voltage than the supply burns out quickly.
- **Damaged wiring.** Burnt terminals and brittle cable cause open circuits and shorts.
- **Moisture.** Bands left in a damp place, or a machine stored for a long time, can show low insulation; follow the band maker's advice before powering them.

## What to send for a replacement quote

1. The band's inside diameter and width, and its power and voltage.
2. The construction (ceramic or mica, one piece or two halves), the connection and the lead length.
3. Any thermocouple hole, and its position.
4. The machine brand and model, the zone, and a photo of the old band.

See the [ceramic heater bands](https://www.imspares.com/parts/ec-ht-01/) we supply, then [request a quote](https://www.imspares.com/request-quote/). The [heaters guide](https://www.imspares.com/injection-molding-machine-parts/heaters/) covers the rest of the heating system.

## Questions

### How do I remove a heater band that is stuck to the barrel?

Isolate the power, fully loosen and remove the clamp bolt, and open the band at its gap. If burnt plastic holds it, warming the zone can soften the plastic, and a heater band removal tool helps free it without bending or tearing the band.

### Do heater bands need to be re-tightened?

Yes. A new band settles and expands on its first heat-up, so check and re-tighten the clamp bolts once the zone has reached temperature, following your site's procedure for working near hot parts. A loose band runs hot and fails early.

### How do I know which heater band has failed?

Look for the zone that heats slowly or not at all while its output is high. Confirm with a clamp meter on its cable, then isolate the power and measure each band's resistance and insulation.

### Can I fit a heater band with a different power?

Use the same power and voltage as the original unless the machine maker approves a change. A different power changes how the zone heats and can upset temperature control.

## Replacement parts

- [EC-HT-01 Ceramic Heater Band](https://www.imspares.com/parts/ec-ht-01/): Full-enclosed ceramic heater band for injection molding machine barrel and nozzle heating zones.
- [MC-GMP-02 Barrel Heating Band Removal Tool](https://www.imspares.com/parts/mc-gmp-02/): Specialized tool for removing and installing heater bands on injection molding machine barrels.