What is possible reasons for Hot Runner Heater shot?

[Sunny]

I am running hot runner molds in production. My hot runner heaters get shot and dead frequently. What are possible reasons for this?
Any idea or suggestion?

[Jendalf]

How did You seted up the heaters (startup procedure) do You have some?

Who is the HR producer?

[hobda1ad]

how is it failing? Are the heater elements burning out, or is it tripping some how. Is the wiring at all melted or frayed. I would check all the wiring for a potential ground.
if its not in the hot runner itself it could be tied to faulty control not regulating the temperature correctly. This happened to me while using an older beat up controller. The Temperature control unit would spike the temperature burning out the hot drop.

[CM8787]

I agree with the above statements.

Check mold plugs that supply power to the heaters.... Feel them with your hands or use a thermal camera. If one is hotter than the others, it could be the plug or wire itself shorting out.

Also, if someone has replaced the fuses with a higher amperage than recommended.... Which I've seen happen.... It could be allowing more power to your heaters than it should when/if there is a change/spike in current and would reduce the life of the heaters.

There might be a heater calibration option also. Maybe they are not calibrated and are overriding their setpoints but the plc is showing they're fine....

[nemanja]

Is it thermocouples connected in correct way? Check if they are damaged and how they are fixed. Happen to me before that cable of thermocouple was cuted, so machine had incorrect reading of temperature.
Do you see any damage on material after shot or purge?

[rickbatey]

I often find that Tech's and bad PID tuning is what kills heaters faster than anything. The Tech's tend to shut off soft start or any programs that limit power and try too dry heaters out just to shave minutes off the change over times. If not that, the PID is wrong or the machine/controller have never been tuned. But loose connections including NOT using terminals on the stranded wire when making heater cables at the pin or bushing connectors.
Rick.