How to Select the Right Nozzle for 3D Printing

March 08, 2018

There are a lot of different nozzles available for 3D Printing and deciding which one to use for a given print can be daunting. You have nozzles in different materials such as brass, nickel plated copper, steel, stainless steel, and even with gem stone inserts. Then you have nozzles with a range of different diameters. This article will offer things to consider when selecting a nozzle.

 

  1. Determine which type of nozzle your printer uses.

    Printed Solid stocks nozzles of the MK8 / E3D V6 style and nozzles that are of the 3D Solex Hardcore Ultimaker 3 Print Core style. The MK8 nozzles are compatible with a vast number of 3D Printers including anything with an E3D or clone hotend (Prusa MK2/3 and clones, CR-10, MP Mini, Robo3D R1/R2/C2, Ultimaker 2-3, Lulzbot Taz5, 6, and Mini, Raise 3D, anything upgraded with an E3D, etc.) At this time, we do not stock any MK10 nozzles, nor do we stock any of the less common nozzles such as the original Ubis female threaded nozzles. However, you can still follow our general guidance to help you select the correct nozzle when you are purchasing from other sites. 

    DECISION POINT: Select a nozzle that is compatible with your printer / hot end.

  2. Determine whether your filament of interest is abrasive and how much abrasive material it contains. 

    A popular misperception is that the abrasive filament is gradually wearing or eroding the nozzle kind of like water on a stone.  This is probably true for some of the mildly abrasive filaments, but the ones we are going to worry about the most tend to have particles that stick out of the molten polymer and actually gouge out the inside of the nozzle.   Check out this pic from E3D's excellent 2015 blog post on this topic for a demonstration of what I mean.  The brass nozzle on the left has run only 250g of colorFabb XT-CF20 and you can see the large gouges in the orifice.  


    In general, the amount of damage to the nozzle is going to be related to both the shape and hardness of the filler in the filament. Filament containing filler of hard sharp particles like glow in the dark, carbon fiber, sand, and glass is the most abrasive. Filament containing particles that are not as sharp, but still relatively hard will be the next most abrasive. This is basically the metal filled filaments. After that, you have things like cork, wood, and the other natural fibers. And finally, you have unfilled 'pure' filaments, although even there, the colorants can be slightly abrasive and will eventually wear your nozzle. Key takeaway here: Carbon fiber, glass, sand, glow in the dark are all very destructive to a nozzle whereas some of the other materials are not nearly as bad.

    Then, going back through that list, for a given material, a higher material loading will cause faster wear. ColorFabb XT-CF20 with 20% carbon fiber fill is going to wear faster than Proto-Pasta Carbon Fiber with about 15% fill but slower than a Xstrand PP-GF30 with 30% glass fiber fill.  This makes a lot of sense because the more fill in the mix, the more tendency there is for the fill to push itself out against the surfaces of then nozzle.

    The more damaging the filament you choose, the more resistant the nozzle needs to be. The gemstone filled nozzles (such as our 3D Solex Everlast Sapphire) will provide the longest life, followed by hardened steel, then stainless steel and copper (both of which only provide marginal benefit over brass in terms of durability, but have other benefits), and finally your standard brass. It's important to note that I did not list any “wear resistant platings” as beneficial here. My personal experience is that wear resistant platings do not hold up well to abrasive filaments and that within a fairly short period of time, you're simply dealing with the softer material underneath. I also don't have tungsten-carbide or tool steel nozzles listed here simply because I have not yet had the opportunity to work with them.

    DECISION POINT: High wear filaments with higher loading such as glass, glow in the dark, and carbon fiber should give strong consideration for a hardened steel or sapphire nozzle. Other filled filaments may warrant consideration of a special nozzle, but don't necessarily require it. 

  3. Determine how often you intend to print with said material. Are you printing production parts 24/7 with colorFabb PA-CF? Or are you just printing for a hobby and want to print an occasional small object in Proto-Pasta Stainless Steel PLA? The key thing to consider here is cost. A hardened steel nozzle is 3-4X more costly than brass, and gem stone is 3-4X over that. If you're only printing a little bit occasionally, it may make more sense to just accept destroying an occasional brass nozzle. If you're printing with our Nylforce Glass Fiber every day, then a sapphire will save you money in the long run even over a hardened steel.

    DECISION POINT: Consider frequency of printing when you select your nozzle. 

  4. How much detail is there in the X-Y plane?

    For example, fine lettering or decoration will require a fine nozle whereas similar detail in the X/Y-Z planes will not require such a fine nozzle. Think of each slice of your 3D Print as a 2D drawing on paper. Could the picture be drawn with a marker or would a finer detail pencil be required? 

    There is a major tradeoff though. A finer nozzle is always going to give slower prints, so our advice here is to use the largest nozzle that your print will tolerate. 

    Here's a little trick. You don't need to set your extrusion width to be the same as your nozzle diameter. There is some range for adjustment. Typically, extrusion width anywhere from 75% to 125% of your nozzle diameter works pretty well. So, for example, if you have a 0.4mm, you can set the extrusion width in your slicer anywhere from 0.4mm and 0.5mm and still expect pretty good results. 

    By the way, larger nozzles also wear much more slowly with abrasive material because the ratio of internal volume to wall surface is higher, so you may want to consider that. 

    DECISION POINT: The finer the detail in the XY Plane, the smaller your nozzle orifice should be. 

  5. Consider whether you are printing lots of fine islands or mostly bulk outlines.

    Objects with lots of islands, such as a voronoi structure will wear the nozzle much faster than simple structures. The reason for this is that the nozzle does tend to rub against the printed part when it moves from one outline to the next. Because of this, the face of the nozzle may become worn as well as the orifice. 

    DECISION POINT: If your typical print has a lot of islands, and you are using abrasive filaments, you may need to consider a wear resistant sapphire or hardened steel nozzle.

  6. Consider how much resolution you need in the X/Y-Z planes.

    Similar to extrusion width in the XY plane, layer height influences resolution in the -Z planes. The thinner your layer height, the finer the surface features you can replicate correctly. “Conventional 3D Printing Wisdom” states that your layer height should be between 25-75% of your nozzle diameter. So, for example, a standard 0.4mm nozzle can readily print layers from 0.1mm-0.3mm while a 0.8mm nozzle can print from 0.2mm-0.6mm. Going to these thicker layers tends to produce a stronger part and produces it much more quickly, but at the expense of resolution on the vertical surfaces of your parts. 

    DECISION POINT: For finer detail in Z, choose a smaller diameter nozzle and lower layer heights. For faster prints, choose a larger diameter nozzle and larger layer heights.

  7. Give special consideration to nozzle diameter for wood and natural fiber filled materials.

    You may have heard that wood filament can clog your nozzle. The reason for this is that when the flow rate is not high enough, these materials tend to have a reaction in the nozzle, crystallize, and clog. So, to solve this, you can simply choose a larger nozzle diameter or you can print with thick layers. We advise at least a 0.5mm nozzle for wood fill and often use a 0.6mm.

    DECISION POINT: Use at least a 0.5mm nozzle for wood or other natural fiber filled materials.

  8. Does your application have any special material contact or thermal transfer issues? We generally don't advise stainless steel nozzles for use with abrasive materials, but if you have a food contact application, you may require that clean material in your printer. Likewise, if you need much higher thermal conductivity or higher overall heat tolerance, you may want to consider nickel plated copper.

    DECISION POINT: Consider special requirements of your material when choosing specialty nozzles.




Matthew Gorton
Matthew Gorton

Author

Matthew Gorton is the founder of printedsolid.com. He is a mechanical / materials engineer by education and has worked as a design, process and quality engineer in the medical, electronics, and aerospace industries. He is enthusiastic about applying all he has learned through these experiences to 3D printing and sharing that with others.


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