Hot runner heaters are critical in controlled plastic flow for injection molding processes. Their role is to sustain the proper temperature in the gate area, manifold, and nozzle, so the molten plastic flows smoothly without degrading. A malfunctioning heater here not only halt flow, it degrades product quality, adds scrap rate, and causes floor backlogs.

That’s why investing in quality from the very beginning is important. Being a provider of custom industrial heating solutions, DHE manufactures high-performance coil heaters and robust cartridge heaters designed to sustain constant load cycles in harsh environments.

But even optimal systems occasionally need to be debugged. Here’s how to do it properly.

1. Begin with the Fundamentals – Is It the Heater or the System?
   Before suspecting a heater is faulty, eliminate external influences. Is the power supply consistent? Is the thermocouple working? Has there been a short circuit or surge elsewhere in the system? Occasionally, so-called heater failure is a sensor problem or a loose terminal connection.
   If your hot runner temperature readings are erratic, it’s a good idea to cross-check the controller and wiring before removing the heater.
2. Visual Inspection: Symptoms You Can’t Ignore
   When a hot runner heater begins to misbehave, its outside usually has a tale to tell. Check for:
    – Burnt marks or discoloration
    – Cracked sheath or bent terminal pins
    – Carbon deposits or melted insulation
   These are early warnings that your heater has overheated or experienced electrical stress. DHE’s coil heaters, for instance, are built with high-temperature nickel-chromium resistance wire and carefully chosen sheath material to withstand such stress.
   Backed by an esteemed portfolio of industry certifications, DHE Heaters stands as a trusted authority and one of the leading industrial heater manufacturers in India, committed to delivering quality, safety, and performance in every product we design.
3. Continuity and Resistance Tests: Rapid Diagnostics
   Check the continuity between heater leads using a multimeter. No continuity typically indicates a fault in the internal resistance wire, which indicates full failure.
   It is also possible to check the resistance and compare it with the rated specification of the heater (usually specified in the technical datasheet). Any large variation could indicate internal degradation or shorting.
   Pro tip: Take a resistance reading logbook for each heater when installing it — this will simplify future diagnostics and improve their accuracy.
4. Hot Spot Mapping: Detect Uneven Heating
   If you see uneven plastic flow or charred material at certain gates, uneven heating is often the cause.
   Today’s hot runner coil heaters are designed for consistent heat transfer. Yet, conditions such as improper installation, incorrect coil length, or inadequate contact with the nozzle body can produce localized over- or underheating.
   In DHE, we frequently collaborate with customers to tailor coil profiles to exactly match the manifold design — this significantly minimizes uneven heating problems right from the beginning.
5. Lifecycle Reality: Every Heater Has Its Limit
   Even the best heater has a limited lifespan, particularly in high-cycling applications such as hot runners. The point is to be aware of wear and tear before it leads to failure.
   If you are changing the same heater several times in a short period, it is well worth reassessing its specs. Is the wattage right? Is the heater under- or oversized for the application?
   We usually recommend clients switch over to cartridge heaters with integral sensors or shift to split-sheath coil heaters for simple replacement and extended service in harsh applications.