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I recently went to a stainless steel nozzle for printing. What I found is it required significantly more heat to print PLA than I was used to. I'm not sure if the PLA itself (a brand I'd never used before) was to blame or if the nozzle properties was causing the needed increase. By an increase in heat needed, I'm used to printing PLA in the 190 °C (+/-5 °C). What I'm using right now to prevent stringing and to get good layer adhesion, I'm having to print at 220 °C.

My question is, does nozzle material typically affect the amount of heat needed to print or should we expect heat shouldn't need to be changed? If the nozzle material does affect it, is there any "rules of thumb" to go by on what to expect?

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  • $\begingroup$ As the answer mentions, brass conducts the heat better. But keep in mind, the temperature sensor measurement is at a specific point. It's also possible the lower heat conductivity means the entire nozzle isn't up to temp yet, and if what would happen if you were to preheat the steel nozzle to the original, lower print temp, and then hold it there an extra few minutes before beginning the print. $\endgroup$
    – Joel Coehoorn
    Oct 27, 2021 at 19:53
  • $\begingroup$ @JoelCoehoorn - Well, I don't think the extra minutes would do much good. We're talking about prints which take several hours (9+) to complete. I was still getting a lot of stringing and having issues with layer separation throughout the print until I turned the heat up. $\endgroup$
    – Pᴀᴜʟsᴛᴇʀ2
    Oct 27, 2021 at 20:12

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Thermal conductivity is the factor to consider in this question. Cost and wear play a part in determining nozzle material selection as well.

According to The Engineering Toolbox, stainless steel has a conductivity (k) between 14.3 and 14.4 with other stainless steel alloys not showing better than 20. Brass (most common nozzle material) lists between 61 and 121, substantially higher.

Of course, one notes the caution with abrasive filament that a brass nozzle will wear. PrintedSolid has a great photo of a worn brass nozzle sliced in half, against a steel version:

brass vs steel nozzle

If one considers that a slower heat transfer gives the device (nozzle) more time to radiate heat to the environment than to pass it along to the filament, the higher temperature makes sense.

Some gemstones have a high thermal conductivity. There are ruby and sapphire nozzles available, providing greater wear resistance without the loss of thermal conductivity.

Regarding a rule of thumb? I have not seen concrete references to what factor to use with temperature increases.

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  • $\begingroup$ The higher thermal resistance not only needs more heat, but it also takes longer for the heat to conduct, so the control system for the heater needs a longer reaction time to add more heat. The longer reaction time can cause temperature excursions both above and below the ideal extrusion temperature. $\endgroup$
    – user10489
    Oct 24, 2021 at 15:51
  • $\begingroup$ +1 for the nice photo, very interesting... however, it is not clear whether each nozzle saw the same amount of use (i.e. meters (or grams) of filament). It might be worth adding that the E3D blog states that 250g XT-CF20 (carbon fibre) was used on both. $\endgroup$
    – Greenonline ♦
    Nov 4, 2021 at 17:14

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