I was interested to examine what difference insulating the hotend heater block would make to hotend performance. I used some Teflon sheet material [ptfe] (sandwich toasting bags!), cut it to shape and then secured it in place with some kapton tape. I've done this in the past as you'll see from this post, but I've never done a graphed comparison of "before" and "after" insulation.
Photo above showing J-Head hotend with newly insulated heater block.
For comparison purposes I dug out a graph of temperature (Deg C) and power (%) over time (minutes) which I had recorded for the same hotend without insulation, while heating to an arbutrary target of 220 Deg C. The J-head was fitted to the printer and both fans running, one under-carriage fan, and the print cooling fan. This graph is below, Temperature over Time in Red, and % power to heater in Green, no insulation on heater block for this graph.
After insulating the heater block I repeated the graphing of the heating process and the tick-over at 220 Deg C which I allowed to run for a few minutes. Graph below...
Comparison and possible benefits of insulation:
Less power required to maintain a given temperature. For my setup, the same target temperature was maintained with <40% power in comparison to approx 50% power for the uninsulated heater block. This is beneficial since having capacity to deliver more heat may enable faster extrusion.
Insulation protects the heater block from stray cooling air. If you are running a cooling fan on PLA then air may also spill over and cool the hotend. It has to reacts by increasing power to maintain temperature. Insulating the heated block reduces the impact of the work cooling fan on the hotend. There is less conflict or fighting between heating and cooling needs when the heater block is insulated.
Slightly faster time to target temperature for insulated heater block. Not significant.
Reduced convective heat once the heater block is insulated. This a very positive benefit as it reduces the risk of insulator temperature rise and hotend jams. It can reduce the risk of x-carriage warping also, where PLA x-carriages are used.
Reduced radiated heat. If you can insulate most of the base of the heater block then there will be less heat radiated toward the printed work. This is good when printing narrow or detailed pieces, and when printing slowly. Often, you slow down when printing fine detail. Cooling of the printed work is essential at this stage to prevent distortion so insulation preventing radiated heat is of benefit.
Technical Notes:
This comparison was conducted with a 30 Watt, 15mm x 6mm, 12v Cartridge Heater in a J-Head Mk V hotend. The controller uses PWM, and PID control cuts in within 10 Deg of target temperature.
PID was retuned and new values set in the Marlin firmware following the insulation of the hotend heater block.
The temperature graphs are automatically plotted by Repetier Host software.
Both graphs were plotted while the printer was static (not printing).
Conclusions:
You could use a variety of materials to do this insulation, including silicon tape or glass tape, to potentially even better effect. It is a bit tedious a process but well worth considering.
There was no comparison made between print quality from an uninsulated versus insulated heater block. The advantages of an insulated heater block are more interms of increased power efficiency, more precision of temperature control, and reduced risk of hotend jamming, rather than print quality increase.
It would be interesting to see others publish such graphs for their printers so comparisons could be made between systems. It would also be good to see hot-end manufactures supply hotends pre-assembled and insulated (like Nophead), or at lease with some suitable and easy to apply insulation material included in hotend kits. I would see this as a selling advantage, even if at a marginal additional cost to the consumer.
Thanks for viewing!
NumberSix
Less power required to maintain a given temperature. For my setup, the same target temperature was maintained with <40% power in comparison to approx 50% power for the uninsulated heater block. This is beneficial since having capacity to deliver more heat may enable faster extrusion.
Insulation protects the heater block from stray cooling air. If you are running a cooling fan on PLA then air may also spill over and cool the hotend. It has to reacts by increasing power to maintain temperature. Insulating the heated block reduces the impact of the work cooling fan on the hotend. There is less conflict or fighting between heating and cooling needs when the heater block is insulated.
Slightly faster time to target temperature for insulated heater block. Not significant.
Reduced convective heat once the heater block is insulated. This a very positive benefit as it reduces the risk of insulator temperature rise and hotend jams. It can reduce the risk of x-carriage warping also, where PLA x-carriages are used.
Reduced radiated heat. If you can insulate most of the base of the heater block then there will be less heat radiated toward the printed work. This is good when printing narrow or detailed pieces, and when printing slowly. Often, you slow down when printing fine detail. Cooling of the printed work is essential at this stage to prevent distortion so insulation preventing radiated heat is of benefit.
Technical Notes:
This comparison was conducted with a 30 Watt, 15mm x 6mm, 12v Cartridge Heater in a J-Head Mk V hotend. The controller uses PWM, and PID control cuts in within 10 Deg of target temperature.
PID was retuned and new values set in the Marlin firmware following the insulation of the hotend heater block.
The temperature graphs are automatically plotted by Repetier Host software.
Both graphs were plotted while the printer was static (not printing).
Conclusions:
You could use a variety of materials to do this insulation, including silicon tape or glass tape, to potentially even better effect. It is a bit tedious a process but well worth considering.
There was no comparison made between print quality from an uninsulated versus insulated heater block. The advantages of an insulated heater block are more interms of increased power efficiency, more precision of temperature control, and reduced risk of hotend jamming, rather than print quality increase.
It would be interesting to see others publish such graphs for their printers so comparisons could be made between systems. It would also be good to see hot-end manufactures supply hotends pre-assembled and insulated (like Nophead), or at lease with some suitable and easy to apply insulation material included in hotend kits. I would see this as a selling advantage, even if at a marginal additional cost to the consumer.
Thanks for viewing!
NumberSix
