Thermal Runaway Test #2
Why 3D Printing Stack Exchange recommends it
3D Printing Stack Exchange answerers link it as a concrete, visual example of what happens when thermal runaway protection is missing or the heater stays on.
Recommended by 1 people across 1 different months, 2019 to 2021.
What it is
A short 2014 demonstration by the Thejollygrimreaper channel of a thermal runaway on a 3D printer hotend. A MOSFET fails in the on state, the heater cartridge keeps heating until it melts through the aluminium block and ignites a PLA print below.
What people said
Recommends user77232 · 2019-03 · 3D Printing Stack Exchange · on “What is Thermal Runaway Protection?”
What is Thermal Runaway? Let's look at a Thermal Runaway Test (#2) [this video] performed by one Chris Bate. In this video the experimenter drove the heating element non-stop until disaster. The Nichrome wire in the heating element melts at about 1,400 °C. Only once it melts, will the circuit will break and the current stop. The aluminum heating block however, melts at 660.3 °C; long before the nichrome melts. Thermal Runaway Protection Thermal runaway protection is a piece of code in the firmware of the printer that checks to make sure that once power is being applied to the heater, the thermistor's resistance is changing within a specified frame (time and amount). This is the basic form of a co
Cites 0scar · 2019-11 · 3D Printing Stack Exchange · on “Are silicone socks safe?”
Silicone socks are safe to use , provided your printer is safely operating and you are using the silicone socks in their operating temperature range . Your current setup is NOT SAFE! When the heater element falls out of the heater block (that should not happen in the first place, please secure it correctly) and heats up to about 800 °C this means that the printer has no active Thermal Runaway Protection (TRP) [LINK] enabled. Basically, when the thermistor doesn't measure a temperature rise while the voltage to the heater element is being scheduled, the firmware should shut down the voltage to the heater element. When this fails, the heater element can reach dangerously high temperatures to s
Cites Trish · 2019-11 · 3D Printing Stack Exchange · on “Are silicone socks safe?”
note that your Incandescence chart is technically the iron one, the one for aluminum is a little different (by a margin of some hundred degrees). Note that Aluminium (which your heater block is made of) melts at 660 °C, so your most worrying item should be the block, which will melt, drip and melt anything below if this goes on for a couple seconds like seen here [this video]
Cites FarO · 2021-01 · 3D Printing Stack Exchange · on “What can cause a 3D printer to catch on fire?”
A normal hotend will not melt or cause fires, usually, see first video. However, if the power regulating unit fails as well and higher voltage is supplied (19 V on 12 V cartridge are enough) it can happen, see second video. Fires are more likely caused by overheating wires, especially where joints are presents. Hotend runaway does not cause fires from the hotend itself, but it could cause fire related to its wiring. Also, the uncontrolled temperature may make the hot end fan fail, worsening the situation. Issues canbe caused also by a runaway on the bed and overheating MOSFETs.