How to Troubleshoot and Prevent Overheating in Injection Molding

Accuracy is the only thing that matters in the cutthroat business of injection molding.

The most minute inconsistency is enough to derail production schedules. It heightens defect levels and ultimately impacts product quality.

In all industries, overheating is a persistent issue. This usually leads back to the band heater. An overly hot heater is one of the most commonly overlooked sources of downtime and inefficiency.

This problem is more prevalent than you may realize. As per a Plastics Technology report, more than 30% of unplanned shutdowns of molding lines are caused by heating system malfunctions.

You know why? The excessive heat is a key factor.

DHE Heaters has established a definitive guide for plant managers, maintenance engineers, and quality assurance staff. This is a helpful guide to those who require long-term, reliable solutions.

Based on our industrial experience as an Industrial Heater manufacturer in India, here is a set of instructions to identify and solve overheating problems in your injection molding applications.

Understanding the Root Causes of Overheating

Let us start by taking a look at the most frequent causes of injection molding heaters overheating:

Thermocouple Malfunction: A faulty or misaligned thermocouple provides the controller with false temperature information. This makes the heater run longer than needed. The usual causes are broken wires, faulty contact against the barrel, or slow feedback.
Poor Barrel Contact: When a heater is not well mounted or has unsymmetrical surface contact, heat escapes into the surrounding environment. What happens to the system? It reacts by producing at an increased output, which causes overheating and energy loss.
Inadequately tuned PID controllers or malfunctioning relays are other reasons for controller faults that create power supply continuity problems and the heater’s temperature going above the setpoint temperature. In multi-zone heating systems, radiation heat from neighboring zones or ventilation deficiency can destabilize the heater output and undermine thermal stability.

Experts at DHE assert that “In 70% of overheating cases we’ve worked on,” says a senior applications engineer at DHE Heaters, “we discovered mismatched thermocouples or faulty sensor feedback loops as the primary cause, not the heater itself.”

Troubleshooting Checklist for Overheating Band Heaters

To identify the root cause and bring your heating system back to optimal working conditions, take the following systematic approach:

Check the Thermocouple:

Inspect for physical injury or loose joints on the thermocouple wire.
Verify the sensor is well-positioned and in good contact with the barrel.
Check sensor accuracy using a multimeter.

Inspect Heater-to-Barrel Fit:

Inspect for gaps, incorrect curvature, or mounting.
Use thermal paste where needed to enhance conductivity.
Inspect the even tightening of the clamping bands.

Check the PID Controller:

In case of frequent temperature overshooting, re-tune and adjust the PID settings.
Check controller relays, particularly in older systems. Damaged relays tend to get stuck in the ‘on’ state.

Assess Cycle Times and Resin Flow

Long cycle times can lead to uneven heat spread and thermal build-up.
Test for delayed resin flow, especially near the gates and cavities.
Double-check Review temperature setpoints for multiple heating zones to maintain consistency.

Smart Upgrades to Avoid Overheating

An upgrade in technology might be needed if the same problems occur after regular maintenance.

What would we at DHE recommend in this scenario?

Band Heaters with Built-In Thermocouples: Our specially designed band heaters include J- or K-type thermocouples built into the unit. It enhances accuracy, minimizes lag, and eliminates misalignment problems.
Ceramic Band Heaters: For increased operating temperatures and improved energy efficiency, ceramic heaters provide high performance in high-load usage. Their multi-layer construction minimizes thermal loss and performs well with cycling.
Thermal Insulation Jackets: Minimize ambient heat loss and keep excessive heat from developing near heater zones. Insulation jackets also shield adjacent components, minimizing total energy consumption.

Advanced Temperature Controllers: Advanced digital PID controllers with auto-tuning and fault diagnostics provide thermal stability and early warning of impending failure.

How DHE Offered Solutions Reduced Downtime by 18%

A major auto-component manufacturer in Pune saw frequent heater failures on their injection moulding line. The failure occurred every 2-3 days, impacting productivity seriously. DHE’s technical team inspected the matter. It was discovered that the original thermocouple was experiencing intermittent wiring fatigue, causing erratic readings. Also, the PID controller had aged-out tuning parameters.

Read how our leading industrial heater in India helped a chemical plant reduce operational costs and improve efficiency.

The Solution:

DHE provided a shielded K-type thermocouple and re-tuned and optimized the PID controller to match the application. The outcome was dramatic:

An 18% reduction in heater-related downtime.
Temperature stability improved to within ±2°C.
Less frequent intervention from the maintenance team is needed.

From Guesswork to Diagnostics

System overheating in injection molding systems must not be regarded in a vacuum. It is usually indicative of systemic failures, misaligned sensors, antiquated control logic, or poorly designed heaters.

Preventive diagnostics, coupled with optimal heating solutions, can significantly reduce downtime and enhance product quality. Don’t forget:

Begin at the sensor.
Check fit and contact.
Trim your controller with care.
Spend in technology that breeds thermal stability.

Partner With DHE Heaters to Overcome Your Overheating Issues

Overheating can be a thorny, money-wasting problem in your injection molding process. Thankfully, the DHE Heaters team is on hand to assist.

Get in touch with us today to arrange a free consultation. Our experts will work with you to:

Diagnose the underlying causes of overheating within your system
Provide targeted recommendations to enhance thermal stability
Install custom-designed heaters and controllers for long-term dependability
Don’t allow overheating to interfere with your production.

Team up with DHE Heaters and begin creating a more efficient, profitable injection molding process.