3D Printing Under Extrusion

Introduction

3D printing is one of the surprising technological inventions. It is a process of making a three- dimensional model with layers utilizing a computer-produced design. 3D printing is of different types, and material extrusion is one of them. In this type of 3D printing, we heat the extrusion head to soften the filament spool inside to sit on the material easily to create models. This way, we keep building layers upon layers. However, at times while layering, the filament does not flow smoothly from the extruder. We call this 3D problem under-extrusion.

So, under-extrusion, just as the term suggests, is a condition in which the printer is unable to supply adequate material through its nozzle. Often, it results in the damage of functional and dimensional stability of the final 3D print. It is because under-extrusion causes the layers to stick and warp up. Sometimes, it breaks down the whole assembly.

There are many reasons for extrusion, and discovering the leading cause is highly unlikely. However, you can detect it with its early symptoms. They include incomplete layers, fragile layers, or layers full of cracks, gaps, or dots.

This article explores the potential reasons and solutions for fixing this glitch. From its settings to the filament spool as well as the nozzle, it is an all-embracing problem.

Main Causes of Under-Extrusion

If the printer seems unable to extrude the volume of plastic you need, it certainly is under extruding. There may be several gaps in the print, broken layers, or thinner layers if this occurs. The infill also might have these spaces or lack of substance, and the layers are not well-linked together. The force there in the head will rise for a while. However, the feeder will skip out, which is a natural action you require. It stops the grinding and prevents the feeder engine from harm. If you check the feeder closely, you will see this skip back, and you can even hear a tack audio coming from that.

The real challenge in fixing an under-extrusion lies in the fact that there are multiple reasons for this. 3D printers concentrate on the magnificent cooperation of the hot end, extruder, and the print head to create a high-quality print. Any malfunction in this collaboration leads to complications. Moreover, most of these intricacies require multiple settings for their handling and ultimate solution.

Tangled Filament

Often the filament gets a twist upon its spool. It may happen when you do not pay heed, when you pull out the filament rashly or, less commonly, during the factory’s formation of the spool. After a little while, the filament would have even more trouble unwrapping from the spool. The feeder will also have difficulty holding up to the necessary flow rate, and there will be under-extrusion. It is not simple to locate, but it should not occur if you store your filaments correctly!

You should either insert it in the spool hole (if it has any) or print few handy clips to keep it stable as you modify the filament. You also need to ensure that its end does not slip under filament over the spool.

Deformation of Teflon Insulator

The filament moves through the Teflon insulating material before hitting the nozzle. Due to the production of material and use of temperature, this section deforms after a while. You need to remove the head section to examine it, and then you can try and put a bit of filament through it. If you detect any friction in it, it’s most certainly time to fix it. You could drill this out at 3.2 mm when you are in a crisis and therefore need to print, but you will also have to modify it.

Ground Filament

When the filament throughout the feeder damages, you should raise the pressure. You would have to utilize a hex key and place it in its feeder’s upper right hole to increase the main feeder’s friction.

Suppose the pressure is right in the feeder, and the filament does not transport according to your expectations. In that case, the feeder may allow a skip back to avoid grinding the filament. However, if there is a ground filament, the feeder would lose its hold upon the filament. Moreover, it would no longer be strong enough to force it, and under-extrusion will arise at that point.

The ground filament region may occur even in Bowden, which is big and flat. You must take the ground filament out of Bowden and cut all the residue after the ground region.

Too Low Temperature

A very significant element in 3D printing is printing temperature.  It differs in terms of filament types, colors, and the flow rate you require. The flow rate has a significant influence on extrusion temperature. If you are printing gradually with smaller layers, it is necessary to limit the temperature. For instance, if you are printing 0.06 mm layers at the rate of 30mm/s, you will lower the temperature (probably depending on the filament brand and color) to as minimal as 190 degrees Celsius for PLA.

If the flow speed rises, the filament has very little time for melting, so you should raise the temperature to accommodate it. The highest limit for PLA is approximately 240 °C. You can use this temperature for a flow rate of 10 mm³/s or more. If you boost the temperature for a typical flow rate above 240 °C, there must be an issue!

Too High Speed

3D printing can be slow, often very long, and we sometimes feel compelled to accelerate the speed to finish the printing job faster. One of the most common causes of under-extrusion is to increase the speed to a considerable level.  We consider that with well-tuned printers, it is possible to go higher. To measure the flow rate, you should multiply the average nozzle size of the layer’s height and velocity. So, if you want to print for 0.2 mm at 50mm/s, the probable flow rate would be 0.4 x 50 x 0.2, which would be equal to 4mm³/s. On Ultimaker 2, in good working condition, these adjustments should run with no problems.

Less Pressure on Filament Feeder

Most 3D printers come with controls for pressure adjustments to change the filament feeders. For a stronghold on the product, this pressure influences the motor over the filament. The motor loses control of printing materials as this friction decreases, adding to a situation of extrusion.

You can check the filament pressure quickly by using your hand. Keep the pigment down while printing when the motor is running. Increase the pressure if you sense the filament slipping.

When you switch the filament, it is also necessary to adjust the feeder pressure, with each maker providing their diameters.

Nozzle Blockage

Occasionally, the 3D printer nozzle needs maintenance. The substance residues and remnants that move through it build up and block the opening in the door, thus causing a major obstacle for you and your three-dimensional visions. The surest risk of extrusion seems to be a blocked nozzle, so maybe you should try out just a little test to be sure.

Separate extruder lever and drive the filament into manually. Your nozzle becomes clear when it goes out with no resistance. Suppose you sense any resistance inside the processor due to any material inside it. In that case, the nozzle becomes clogged and requires washing.

Clogged Extruder

If the extruder head holds stuck items like filament remnants, the new thread you pass through it will face multiple frictions while going through the nozzle.

This added pressure slows the printing material from touching the nozzle, resulting in extrusion. The clogging may even be in the engine of the feeder. Test to ensure the bits of residual filament do not contaminate the feeder motor cog that drives the materials through the nozzle.

Incorrect Nozzle Height

Your nozzle needs to be there at the perfect height from the print ground to effectively print an item. The print content requires to travel a larger area to hit the surface because the nozzle is very high. This more extensive area results in temperatures that are colder. The outcome is that the substance would have difficulty complying with it.

On the contrary, if the nozzle becomes very short, there can be other issues. First, it will not allow the content to extrude properly due to less space between the nozzle and the print ground. This short nozzle will also smear the thermoplastic across the top by the nozzle.

Second, the inadequate distance between the nozzle and surface would trigger the backward extrusion. Eventually, the product will start to creep up towards the nozzle and create a clog.

Bad Quality Filament

Filaments are not always similar. Filaments of low consistency do not stand stringent resistance tests. This low-quality results in varying widths in the strand of the filament.

You may want to check our buying guide for the best PLA filaments for 3D printing

A poor-quality filament does not only take longer to melt but is also hard to extrude. It creates clog and blocks repeatedly. It is because of the inexpensive fillers and unwanted toxins that hide inside such filaments. These substances accumulate or entirely clog within the nozzle.

Dirt and Dust

Dust and dirt will also stick to your filament and fly down to the hot end with it, despite your great effort. Once there, dirt burns in the nozzle’s warmth and begins adhering like charcoal within the surface of the nozzle.

It will begin to restrict the nozzle’s openings’ width by accumulating carbon deposits underneath and obstructing the print content flow.

How to Fix Under-Extrusion in 3D Printing

Check Equipment and Materials

Filament Diameter

This solution seems obvious, but this is a very basic mistake too. When you are utilizing a filament with a diameter of 3 millimeters, but your slicer adjustments are around a diameter of 1.75 millimeters, the extruder would not work at a reasonable rate. Moreover, minor diameter differences are sufficient to build issues with under-extrusions, reinforcing the value of a high-quality, reputable source while purchasing the filament. Take a sharp look at filament diameter to make sure the same reflects on your software slicer.

Rewind and Unwind the Spools

Roll up your spools to guarantee that filament rolls smoothly through the printer so that you can untangle the filament without overlapping. From your spools, the threads of filament should not fall off.

Unwind and rewind the spools to accomplish flawlessness, smoothing out all knots which may provoke the material to tangle. To avoid overlapping, coil it firmly. Untangling the filament allows you to materialize your 3D models quickly and without any glitches.

Check Printer Settings

Monitor Feeder Performance

Feeder is among the components of a 3D printer that can also trigger under-extrusion if it does not perform the intended function. Suppose the feeder does not appear to catch over to the filament to transfer it into the extruder. In that case, you should raise the feeder’s pressure.

However, while straightening the filament, be careful not to break it as it will further slowdown the process of filament feeding into the extruder.

 Checking Printing Temperature

Under-extrusion may also result from a mismatch between printing temperature and its speed settings. When you feed the filament quickly to the hot end nozzle, it does not get ample heat penetration to melt appropriately and cause under-extrusion. Therefore, make sure that the temperature and printing speed match.

Set Multiplier Extrusion

Suppose your extruder is not moving the filament outward fast enough. In that case, you should raise the extrusion multiplier by increments of 2.5 percent, taking caution not to hit the stage, which leads to immediate blockage. Bear in mind that you may even need to raise the printing temperature concurrently.

Check Internal Parts

Printer Nozzle Blockage

Polluted nozzles are possible because of the dust and polluted filament in the opening. It would be best if you still were careful not to place the nozzle’s height too close to the printing surface. Professionals recommend that you must not leave the printer unused along with a heated nozzle.

Though that is not something that periodic cleaning and repair will not fix, you should frequently spruce the nozzle with a stiff brass brush by brushing it. That will help you clean off the whole ground and clear of particles that might cause a blockage.  

The next move is to turn on the printer, let the printer heat up, and inject a hypodermic needle to unblock it.

Check the Extruder Idler

If your extruder has something wrong with it, you have zero choices but do some disassembly. A damaged extruder, sadly, would almost definitely cause problems with under-extrusion. Many extruders include two main components, an idler and a drive gear. They convey the filament to the hot end nozzle. Suppose the drive gear has to catch the filament. In that case, the idler gives a frictionless surface against which the printer keeps the filament.

Check Gear Head of Extruder

The gear head is the second part of the extruder. The critical concern with the extruder’s gear heads is that it traps filament material in the spaces between the gear’s teeth. It decreases the catching power of the drive gear, thereby resulting in low extrusion.

The Right Order to Follow

For fixing under-extrusion, the first thing is to define the problem, then execute the cure. Begin with the simplest condition for testing.

It is essential to follow the right order for diagnosing the cause of under-extrusion. The order we recommend is-speed, temperature, nozzle, the tension of the feeder, and then filament problems. For instance, if the printing speed is too fast, your printer may face problems extruding fine filament in a brief span. Try to reduce the printing speed by 20 mm/s, then notice the effect. If the reduction in speed or temperature doesn’t solve the problem, check the nozzle for a possible jam. Clean it thoroughly and make sure there is no clog in it. Again, check the effect. If it also does not make any difference, check all the other factors which we mentioned above. It will help resolve the issue.

What Must You Never Do?

What you should not do while a printer is under-extruding is raise the flow. Assume that the printer nozzle is a people-filled real-life passage. It gets narrower and comes to an end with one door to the exit. If the number of people inside is large, and they do have much trouble getting out, wonder what might occur if you raise the number of people in the corridor!

Under-extrusion isn’t a natural behavior; however, we should try to overcome its root cause. Reaching the leading cause by following the step-by-step procedure we discussed in the last heading is very important.

Final Words

Under-extrusion is something through which all the beginners and experts in 3D printing would go. Hopefully, using the simplest solution possible, this guide may help you solve your under-extrusion dilemma. If none of them was the reason for under-extrusion in your 3D printer, simply clear the nozzle with plenty of cold pulls. Then uninstall the head and inspect the Teflon insulator if you ever feel any under-extrusion.

You may also want to check our article for 3D printing over extrusion