What Causes Lines in 3D Prints and How to Fix Them

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27 Feb, 2023

Lines in 3D Printing

Lines in 3D Printing

In the world of 3D printing, lines of deposited material are the key factor in disturbing quality and aesthetics of the final print. In this article we will discuss the causes of lines in 3D Prints and how they can be avoided.

What are the lines in a 3D print?

Every 3D-printed part's surface is made up of hundreds of separate layers. If everything is in order, those layers would appear to be one continuous and smooth surface. However, if a problem arises during the printing process with only one of such layers, the fault can be quite obvious from the print's exterior. On the sidewalls of the printed components, these incorrect layers may show as lines or ridges. Frequently, the flaws would appear in a cyclic manner, meaning that the patterns will recur (i.e. once after every 10 layers).

What are the causes for these lines to appear in a 3D print?

In general, such irregular lines are generated by inaccuracy or misplacement of a single layer with respect to the subsequent layers. In any case, why does this mismatch begin to form? There are a number of reasons behind it. Let’s explore these reasons and how they affect the overall process of printing:

Over-Extrusion

Over-extrusion is the main reason why a 3D print has lines. There doesn't necessarily have to be significant over-extrusion; it might simply be a small amount of additional material being pushed out when the level is printing. Over extrusion is the phenomenon that occurs when the 3D printer's nozzle extrudes far more filament over the build plate. The problem, which is associated with the extruder's flow rate, can cause a variety of issues, including leaking, blobs, and threading, in addition to poor print quality as a whole and geometric error. Interestingly, over-extrusion may occur in any FDM 3D printer, regardless of the computer system or materials used.

Knowing when the 3D printer is over-extruding is crucial, as is acting swiftly to address the issue. Not only may excessive extrusion lead to delays and material loss, but it may also jam the nozzle of the printer.

High Temperatures

The temperature being greater than it should be is most frequently the source of over-extrusion. A large temperature differential can cause the print to appear melted, whilst a tiny one will simply cause a small quantity of undesired plastic to emerge. Some individuals print at a temperature that is far higher than is necessary. Although certain PLA filaments have a melting temperature of 180 degrees Celsius, most hobbyists prefer to work at temperatures between 200 and 215 degrees.

There's no denying that greater temperatures can improve layer adhesion, but it also comes with a number of problems. Blobbing and gushing are two common problems that affect individuals all over the world. In order to avoid any further problems, one should try to operate at the lowest temperature practicable. However, it’s likely too low if there is under-extrusion or poor layer adherence.  Finding the ideal setting for the printers and filaments just requires a little time and effort but it pays off in the long run.

Abrupt Temperature Changes/Fluctuations

The thermistor can cause wrong temperatures sometimes leading to difficulties printing but the temperature fluctuations create an entirely new problem. The heated end's temperature is measured via a thermistor, but the temperature setting is controlled by the PID controller. Temperature changes are typically rather obvious.  The problem arises if the temperature changes by more than 5 degrees Celsius.

In such a scenario, one can attempt to re-calibrate the PID controller but to do that a manual will be required for that particular printer. But, if that doesn't work, the circuit board for the printer might need changing.

Error in filament extruder temperature optimization

Mechanical Problems

Z-banding refers to the presence of horizontal lines across a 3D print's casing. These designs often reoccur every few layers. Various problems can lead to z-banding, but the main cause for z-bending is a bent lead screw. A movement may severely impact the precision of the 3D print and may result in lines across the 3D print if the printer's lead screw is distorted at particular layer heights.

3d printer rods wear out after long continuous use and it’ll affect the z-axis functioning. This will have an impact on the printing design and result in the lining effect. Additionally, if the wheel or the belt is out of alignment the print output might experience strange lines on the sides and surface. Another mechanical issue that might cause Z-wobble and other flaws like lines on the sides of the 3D print includes slow linear bearing.

Damaged Extruder Nozzle

A damaged extruder nozzle can cause prints to have a really strange horizontal pattern on every layer. This can happen when the tip of the nozzle gets scrapped.  It gives off an intriguing feel but also has a terrible appearance.   Two things may cause this to happen. The primary reason is that the nozzle scratches the tip off because it is very near to the bed. The second scenario is that the user unintentionally scrapes it away while attempting to clean it.

Always clean the nozzle with extreme caution, especially if the metal is heated and pliable. Use one of the replacement nozzles that likely came with the printer if the original gets damaged. If the nozzle is a different size then alter the slicer settings to adjust to the new-sized nozzle.

New and used brass nozzles for 3d printer

Printing too Quickly

An automobile will slip around a turn if it is driven too rapidly. Similarly, the print's sides will be covered with extra filament if the extruder is operating too rapidly. This may occasionally be more obvious on curved sides or it may just be present on plain edges as well where it’ll extrude more material. Whatever it is, it may likely be lessened by slowing down the printing speed.

Unstable Print Surface

The printing bed or the ground the printer is placed on can both be referred to as an unstable surface. Both of these can produce ringing lines. The back-and-forth motion of the printers causes vibrations that result in ringing. If it's severe indeed, it will make the prints seem dreadful. Using clamps for the printer bed could help stabilize it. The higher the prints are, the more the bed will shift while printing.

Bad Filament Diameter Quality

A 3D print failure finally occurs because uneven filament diameters impact the flow rate for filament ejection, which leads to poor surface finish, extruder jams, inconsistent gaps within individual extrusions, and excessive overlapping. Also, if the filament that is being employed isn't the same diameter that the slicer expects, the print won't look as well as it should. In reality, it may result in tiny holes, missing pieces, the excessive filament in some areas, and other problems. It is crucial that the filament adheres as closely as possible to the specification.

How to fix lines on the side of 3d prints?

All the fixes for the aforementioned issues, which result in lines showing up on the 3D prints, can be found in the following subsections.

Fixing Extrusion Issues

Excess filament coming out when the printer is over-extruding makes the layers thicker than they should be. To resolve this issue, one can lower the filament flow rates and/or reduce the temperature of the extruder to avoid excess melting of the filament.

Over time, the extruder nozzle can be subject to general wear and tear and can get damaged while scraping. In such cases, it is best to replace the nozzle with a better-quality one for extended usage. If an abrasive filament is being used for printing, opting for a hardened steel nozzle would be a better option.

Fixing Temperature-Related Issues

Higher temperatures make the extrusion of plastic much easier and more fluid but without much control. To fix this problem, the printer should be operated at lower temperatures. However, if the printer is under extruding then slowly increase the temperature till the optimum temperature range for the printer has been determined.

Another issue is abrupt temperature changes or fluctuations resulting when the PID controller is out of tune. Making sure that the controller is properly tuned with temperature variation not greater than ±2°C. Also, a brass nozzle can be utilized to avoid such fluctuations, since it provides better thermal conductivity.

Fixing Mechanical Issues

Mechanical problems like bent screws, wearing rods, and linear bearing issues can lead to z-bending. Proper maintenance of these mechanical parts can help prevent this problem. However, if the lead screw is significantly bent then it should be replaced with a high-quality screw. Also, lubricating the printer rod and properly adjusting the belt and wheel can smoothen the movements and prevent the formation of weird lines on the prints.

Fixing Issues Related to Printing Speed

When the extruder is printing too quickly, it tends to deposit extra filament material on the sides. In such a scenario, one should lower the printing speed. This’ll give the proper amount of time for layers to properly adhere. One can try changing the flow rate if it is desirable or necessary to maintain the present speed. But eventually, it gets too quick for the printer, which will lead to further problems. Reduce the printing speed if it exceeds the recommended rate for the printer or tries initially modifying the flow rate and cooling if the current speed is below that.

Fixing Filament Diameter Issues

Poor-quality filaments might change the extruder's feeding pressure, which can result in lines showing on the sidewalls of the 3D print. One can buy a better quality filament from a trusted provider to avoid this issue. Also, make sure that the measured diameter of the filament is within the acceptable range of the extruder nozzle.

Fixing Issues Related to Printer’s Stability

The location of the printer is also important. The printer will vibrate if the stand it's on is not solid. The printer may need some vibration-absorbing soles if the lining persists even after securing the table. They are usually available at the hardware store or can also be procured from the online marketplace. Better still, the flexible filament may be used to create them. Another thing regarding vibrations to be aware of is that the higher up a tall, narrow print is, the more oscillations it will produce. Curving the print can give greater solidity and stop the ringing effect.

Key Takeaways

Most people think that layer lines present in 3D-printed components are a serious issue. The extra unwanted lines and deposits in the print ruin the quality of the overall print. One may conceal or get rid of layering lines on the 3D-printed objects in a number of ways. Starting the print at a lower temperature and having the PID controller properly adjusted can prevent the excessive melting of filaments and over-extrusions. Also, it is important to maintain all the mechanical components in top-notch condition to avoid z-bending and help maintain the quality of the 3d prints. Other aspects like printing speed, filament diameters, and stability of the printer’s base should also be carefully monitored and adjusted in order to obtain a hitch-free and good-quality 3d output.

 References

  1. Lines on the Side of Print | Simplify3D Software [Internet]. Simplify3D. 2023 [cited 2023 Feb 24]. Available from: https://www.simplify3d.com/resources/print-quality-troubleshooting/lines-on-the-side-of-print/
  2. Boissonneault T. Dealing with Over Extrusion in 3D Printing [Internet]. Wevolver. 2022 [cited 2023 Feb 25]. Available from: https://www.wevolver.com/article/dealing-with-over-extrusion-in-3d-printing
  3. Simmons J. Why Are There Lines on the Side of Your 3D Print? [Internet]. The 3D Bros. 2023 [cited 2023 Feb 25]. Available from: https://the3dbros.com/why-are-there-lines-on-the-side-of-my-3d-print/
  4. Admin 3dfuel. Does Filament Quality Really Matter? [Internet]. 3D-Fuel. 2020 [cited 2023 Feb 26]. Available from: https://www.3dfuel.com/blogs/news/does-filament-quality-really-matter#:~:text=If%20the%20filament%20you
  5. Jallad S. How To Get Rid Of Lines In 3D Printing, Flow Rate and Homing in 3D printing. - 3D Print Schooling [Internet]. 3dprintschooling.com. 2021 [cited 2023 Feb 26]. Available from: https://3dprintschooling.com/how-to-get-rid-of-lines-in-3d-printing-flow-rate-and-homing-in-3d-printing/
  6. Dwamena M. 9 Ways How to Get Rid of Lines on the Side of 3D Prints – 3D Printerly [Internet]. 3dPrinterly. 2023 [cited 2023 Feb 26]. Available from: https://3dprinterly.com/how-to-get-rid-of-3d-print-lines/
  7. Ahmed S. A Quick Guide To 3D Printing Without Getting Layer Lines [Internet]. 3d Gear Guide. 2022 [cited 2023 Feb 26]. Available from: https://3dgearguide.com/3d-printing-without-getting-layer-lines/

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