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3D printing plastic strength
Are 3D Printed Parts Strong & Durable? PLA, ABS & PETG – 3D Printerly
Companies worldwide have recently turned to 3D printing to create technical parts quickly while saving some money in the process. But, developing 3D versions of pieces involves using new materials that might not be as durable. So, are 3D printed parts strong?
3D printed parts are very strong, especially when using specialized filament like PEEK or Polycarbonate, which is used for bullet-proof glass and riot shields. Infill density, wall thickness and print orientation can be adjusted to increase strength.
There’s a lot that goes into the strength of a 3D part. So, we’re going to be reviewing the materials used during 3D printing, how strong they really are, and what you can do to increase the strength of your 3D printed parts.
Are 3D Printed Parts Weaker & Fragile?
No, 3D printed parts aren’t weaker and fragile unless you 3D print them with settings that don’t give strength. Creating a 3D print with a low level of infill, with a weaker material, with a thin wall thickness and low printing temperature is likely to lead to a 3D print that’s weak and fragile.
How Do You Make 3D Printed Parts Stronger?
Most 3D printing materials are rather durable on their own, but there are some things that can be done to increase their overall strength. This mostly comes down to the minor details in the design process.
Most important would have to be manipulating the infill, wall thickness, and the number of walls. So, let’s take a look at how each of these factors can impact the strength of a 3D printed structure.
Increase Infill Density
Infill is what’s used to fill in the walls of a 3D printed part. This is essentially the pattern within the wall that adds to the density of the piece overall. Without any infill, the walls of a 3D part would be completely hollow and rather weak to outside forces.
Infill is a great way to increase the weight of a 3D part, also improving the strength of the part at the same time.
There are plenty of different infill patterns that can be used to improve the strength of a 3D printed piece, including a grid infill or a honeycomb infill. But, just how much infill there is will determine the strength.
For regular 3D parts, up to 25% is likely more than enough. For pieces designed to support weight and impact, closer to 100% is always better.
Increase Number of Walls
Think of the walls of a 3D printed part as the support beams in a house. If a house only has four exterior walls and no support beams or interior walls, just about anything can cause the house to collapse or give under any amount of weight.
In the same way, the strength of a 3D printed piece will only exist where there are walls to support weight and impact. That’s exactly why increasing the number of walls inside a 3D printed piece can increase the strength of the structure.
This is an especially useful strategy when it comes to larger 3D printed parts with a greater surface area.
Increase Wall Thickness
The actual thickness of the walls used in a 3D printed piece will determine how much impact and weight a part can withstand. For the most part, thicker walls will mean a more durable and sturdy piece overall.
But, there does seem to be a point at which it’s difficult to print 3D printed parts when the walls are too thick.
The best part about adjusting the wall thickness is that the thickness can vary based on the area of the part. That means the outside world probably won’t know that you’ve thickened the walls unless they cut your piece in half to dissect it.
Generally speaking, extremely thin walls will be quite flimsy and won’t be able to support any exterior weight without collapsing.
Generally, walls that are at least 1.2mm thick are durable and strong for most materials, but I’d recommend going up to 2mm+ for a higher level of strength.
The Strength of Materials Used to Create 3D Parts
3D printed parts can only be as strong as the material that they’re made of.
With that said, some materials are a lot stronger and more durable than others. That’s exactly why the strength of 3D printed parts varies so greatly.
Three of the more common materials used to create 3D parts include PLA, ABS, and PETG. So, let’s discuss what each of these materials is, how they can be used, and how strong they really are.
PLA (Polylactic Acid)
PLA, also known as Polylactic Acid, is perhaps the most popular material used in 3D printing. Not only is it quite cost-effective, but it’s also very easy to use to print parts.
That’s why it’s often used to print plastic containers, medical implants, and packaging materials. In most circumstances, PLA is the strongest material used in 3D printing.
Even though PLA has an impressive tensile strength of about 7,250 psi, the material does tend to be a little brittle in special circumstances. That means it’s a little more likely to break or shatter when placed under a powerful impact.
It’s also important to note that PLA has a relatively low melting point.
When exposed to high temperatures, the durability and strength of PLA will severely weaken.
ABS (Acrylonitrile Butadiene Styrene)
ABS, also known as Acrylonitrile Butadiene Styrene, isn’t quite as strong as PLA, but that doesn’t at all mean that it’s a weak 3D printing material. In fact, this material is much more capable of withstanding heavy impact, often flexing and bending rather than shattering completely.
That’s all thanks to the tensile strength of about 4,700 PSI. Given the lightweight construction yet impressive durability, ABS is one of the best 3D printing materials out there.
That’s why ABS is used to make just about any type of product in the world. It’s quite a popular material when it comes to printing children’s toys like Legos, computer parts, and even piping segments.
The incredibly high melting point of ABS also makes it able to withstand just about any amount of heat.
PETG (Polyethylene Terephthalate Glycol-Modified)
PETG, also known as Polyethylene Terephthalate, is usually used to develop more complex designs and objects when it comes to 3D printing.
That’s because PETG tends to be much denser, more durable, and more rigid than some of the other 3D printing materials.
For that exact reason, PETG is used to make plenty of products like food containers and signage.
Why Use 3D Printing at All?
If 3D printed parts weren’t at all strong, then they wouldn’t be used as an alternative production method for many supplies and materials.
But, are they as strong as metals like steel and aluminum? Definitely not!
However, they are quite useful when it comes to designing new pieces, printing them at a lower cost, and getting a good amount of durable use out of them. They’re also great for small parts and have a generally decent tensile strength given their size and thickness.
What’s even better is that these 3D printed parts can be manipulated to increase their strength and overall durability.
Conclusion
3D printed parts are definitely strong enough to be used to make common plastic items that can withstand great amounts of impact and even heat.
For the most part, ABS tends to be much more durable, though it does have a much lower tensile strength than PLA.
But, you also need to take into consideration what’s being done to make these printed parts even stronger. When you bump up the infill density, increase the number of walls, and improve the wall thickness, you’re adding to the strength and durability of a 3D printed piece.
What is the Strongest 3D Printer Filament?
What is the strongest 3D printer filament? Airwolf 3D CEO and Co-Founder Erick Wolf gives a rundown on the results of a 3D printer filament strength test featuring PLA, ABS, Nylon, and Polycarbonate. This blog post was adapted from the video, What is the Strongest 3D Printer Filament? and is part of the series, Hooked on 3D Printing: A Study in Material Strength.
Hi everybody, Erick Wolf here from Airwolf 3D. Today I’m going to talk about the strength of commonly — and not so commonly — 3D-printed materials. Specifically, we’ll be testing PLA, ABS, NYLON 910, and POLYCARBONATE.
We’ll test each material by printing a common hook and then loading the hook with weight until it fractures. The hook that takes the most weight will correspond to the material with the greatest tensile strength. To back it up, we’ll pull some information from a great article on 3DPrint.com referring to tensile strength of commonly 3D-printed materials.
To keep it interesting, we set up a fun experiment using our 3D-printed hooks to pick up a tractor tire weighing 150 pounds and loaded with hundreds of pounds of additional weights from Precision Fitness, our local gym here in Costa Mesa, CA.
To test the strength of hooks printed in different 3D-printing materials, the Wolfpack loaded up a tractor tire with weights from a local gym and 50-lb bags of raw polycarbonate plastic pellets that the company uses for manufacturing filament.
So let’s get on with it and start talking about our materials. The most popular desktop filament is probably polylactic acid, or PLA. We print PLA with the heated bed at 60 degrees Celsius and a coat of Wofbite Nano. It’s also best to keep the lid off as PLA is sensitive to high temperatures. PLA is an environmentally friendly, compostable filament that prints easily at low temperatures and looks great. It’s also pretty strong.
It’s pretty darn impressive that PLA survived up to a 285 lb lift. We probably could have eked a few more pounds out of it, but the hook was already yielding. Truth be told, we were surprised with PLA’s strength. However, with a tensile strength of 7,250 psi, this is a strong material. With that comes a caveat, In this case, a caveat that can swallow the entire utility of PLA. Because PLA is biodegradable, don’t be surprised if it starts breaking down during use. In the sun especially, PLA is unpredictable and can change forms with a few hours. So please don’t print your tow hook out of PLA — it should not be used for anything supporting a load.
Stick to what PLA is best for, toys and figurines.
Material Showdown: ABS vs PLA
Next up, let’s look at a real engineering material, ABS. ABS is used just about everywhere, including your car, home, and office for everything from interior bits and pieces to your mouse and computer case. Airwolf 3D was one of the first companies to make desktop 3D printers capable of printing in ABS. Why? Because ABS is an engineering-grade material that can be sanded, finished, painted, and used in real world applications for end-use components. In fact, we printed out thousands of 3D printers using ABS as the main material. For best printing, keep your heated bed to at least 120 degrees Celsius, apply a coat of Wolfbite and print in an enclosed environment. We optimized the AXIOM 3D printer for ABS and hotter materials.
Now for the real test. How did ABS compare to PLA? As ABS and PLA are the most frequently used materials on the desktop, which one is stronger? Turns out ABS is weaker than PLA.
With the same 285 lb load, the ABS hook snapped instantly.
We didn’t bother to reduce the weight as this is really meant to be a test of ultimate strength. The results should not come as a surprise, however, because ABS has a lower tensile strength of 4,700 psi compared with 7,250 psi from PLA. However, you could design a stronger hook using more material out of ABS that could match our PLA hook’s strength. In that case, you would not have to worry about the unpredictable nature of PLA.
But we’re really here to find the strongest 3D printing material for your desktop printer. And for that, we need to start looking into more exotic materials, starting with nylon.
Testing the Strength of Nylon
There is a great type of nylon for 3D printing called Nylon 910. We print Nylon 910 at 250 degrees Celsius with the bed at 70-100 degrees Celsius, using Wolfbite Nitro for the ultimate bed adhesion. Also remember to print in an enclosed environment for best results.
Nylon is a great material for making structural parts. Compared to ABS with a tensile strength of 4,700 psi, nylon’s estimated tensile strength of 7,000 psi is head and shoulders above ABS. Notice how I stated “estimated.” I say that because there are several different types of nylon with strength varying in between.
In the video, notice how the hook initially bent, but didn’t yield until hundreds of pounds later, 485 pounds in this case. As we can see, nylon is a predictable material that works great in load applications. In fact, every Airwolf 3D printer built over the course of the last three years uses 3D-printed nylon gears for the ultimate in performance and wear characteristics.
Polycarbonate: The True King of Desktop 3D Printer Filaments?
Now let’s talk about polycarbonate. Since 2014 with the introduction of the Airwolf HDx, we’ve been printing in this incredibly strong and heat-resistant material. What makes printing polycarbonate unique is the extraordinarily high temperatures.
First, the bed should be at 145 degrees Celsius or higher. Second, the head should be at 290 degrees Celsius or higher. Both of those temps are far, far out of the range of conventional desktop 3D printers. Finally, you’ll need to enclose polycarbonate as it will warp quickly if printed in an open environment.
So how did polycarbonate fare? We suspended 685 pounds from that little hook! Polycarbonate is the undisputed king of materials for desktop 3D printing. Even we were surprised at polycarbonate’s strength. In comparison to nylon at 7,000 psi, polycarbonate’s tensile strength of 9,800 psi makes it the ideal choice for high-strength, functional components. When printed correctly, such as on an Axiom 3D printer, PC is an incredibly strong material. Also, remember that PC has a much higher glass transition temperature than all the other plastics mentioned here. Compared to its closest competitor, ABS, polycarbonate can take about 40 degrees more heat before deforming.
In short, polycarbonate is the undisputed king of desktop 3D materials.
Tensile Strength ISO 527
In addition to this fun “hook test”, Airwolf 3D staff tested its engineering-grade materials using consistent, repeatable ISO 527 standards. You can read more about this here: Material Testing Part 1: Tensile Strength ISO 527 and you can also download data sheet for each material by following the hyperlink below.
910 ALLOY | MG94 ABS FILAMENT | PETG FILAMENT | PREMIUM PLA FILAMENT | POLYPROPYLENE FILAMENT | WOLFBEND TPU FLEXIBLE FILAMENT | BRIDGE NYLON FILAMENT | |
|---|---|---|---|---|---|---|---|
| Specifications | |||||||
| TENSILE STRENGTH | 47.7 MPa | 46.4 Mpa | 50.0 MPa | 64.4 Mpa | 12.8 MPa | 23.8 MPa | 40.2 MPa |
| ELONGATION AT BREAK | 28.8% | 21. 6% | 21.5% | 15.3% | 716.0% | 909.0% | 401.0% |
| EXTRUDER TEMPERATURE | 240C – 250C | 235C – 260C | 235C – 255C | 195C – 225C | 210C – 220C | 230C – 245C | 255C – 270C |
| BED TEMPERATURE | 70C – 80C | 110C – 130C | 80C – 120C | 60C – 70C | 80C – 100C | 40C – 60C | 80C – 100C |
| HEATED BED | Required | Required | Required | Optional | Required | Optional | Required |
| RECOMMENDED BUILD SURFACE | Wolfbite NITRO | Wolfbite for ABS, PETG, TPU, and TPE | Wolfbite for ABS, PETG, TPU, and TPE | WolfBite Nano | Wolfbite ULTRA | Wolfbite for ABS, PETG, TPU, and TPE | Wolfbite NITRO |
| DIAMETER | 2.88mm | 2.88mm | 2.88mm | 2.88mm | 2.88mm | 2.88mm | 2. 88mm |
| COLOR | Black, Natural | Black, Black 5lbs, Natural, Natural 5lbs, White, White 5lbs | Black, Blue, Red, White, Yellow | Black, Blue, Green, Natural, Orange, Red, Silver, White, Yellow | White | Black, Blue, Clear, Red, White | Black, Natural |
| COMPATIBLE MACHINE | AXIOM, AXIOM 20, AXIOM Dual Extruder, EVO | AXIOM, AXIOM 20, AXIOM Dual Extruder, EVO | AXIOM, AXIOM 20, AXIOM Dual Extruder, EVO | AXIOM, AXIOM 20, AXIOM Dual Extruder, AXIOMe, EVO | AXIOM, AXIOM 20, AXIOM Dual Extruder, EVO | AXIOM, AXIOM 20, AXIOM Dual Extruder, AXIOMe, EVO | AXIOM, AXIOM 20, AXIOM Dual Extruder, EVO |
| 910 ALLOY | MG94 ABS FILAMENT | PETG FILAMENT | PREMIUM PLA FILAMENT | POLYPROPYLENE FILAMENT | WOLFBEND TPU FLEXIBLE FILAMENT | BRIDGE NYLON FILAMENT | |
Download Material List
Did you know that you can 3d print in over 40+ materials?There are dozens of types of filaments available to you, including harder polymers such as polycarbonate and flexible materials such as TPU.
Download this handy list of commonly used materials. This two page reference chart includes the recommended hotend temperature and bed temperature for optimal 3D printing settings of each material.
What is the most durable material for 3D printing?
3DPrintStory 3D printing process What is the most durable material for 3D printing?
While the 3D printing process seems like a great alternative to traditional manufacturing methods, the parts produced can be fragile and unusable. As a rule, this is the result of using standard materials that are not designed for strength and durability. But there is a solution: use durable materials! Durable 3D printing materials can greatly enhance your options, as you can print parts and assemblies for small projects without fear of breakage.
In this article, we'll take a look at the three most durable types of 3D printing materials. However, before that, we will take a closer look at what strength means in terms of filament materials.
What is strength and how do we evaluate it?
The strength of a material can be measured and evaluated in different ways. In this article, we will mainly use tensile strength (stress before something breaks). We will list the tensile strength of each 3D printing material in pounds or pounds per square inch (PSI).
Despite the obvious number of pounds the material can support, there is still a margin of error depending on how the part was printed. We've compiled research from a variety of sources to make sure these three materials are the strongest.
You must also understand that the material itself is not the only factor that affects the strength of the finished product. The design itself, post-processing and the 3D printing process also affect the strength of the part.
Polycarbonate
Polycarbonate (PC) is considered by many manufacturers and reviewers to be the strongest 3D printing filament available. In particular, it is possible to achieve high strength of polycarbonate products by 3D printing with an all-metal hot end and a 3D printer in a case that is isolated from the influence of the external environment.
Some Numbers
Airwolf 3D has come to the conclusion after many filament tests that polycarbonate is the best choice of durable filaments for desktop 3D printers. They were able to hang up to 685 pounds on a polycarbonate printed hook and found that this material had a tensile strength of 9800 psi. In contrast, the same part printed in PLA could only support 285 pounds.
Using a similar test, MatterHackers studied the tear strength of this type of thread, as well as a number of other materials. They were able to hang an average of 409 pounds on the polycarbonate hook, while the PLA parts had a significantly lighter average weight of just 154 pounds.
Finally, renowned 3D printing YouTuber Thomas Sunladerer reviewed several polycarbonate materials and gave very positive feedback on the strength of the material.
3D printing with polycarbonate
It is worth noting that the quality of 3D printing with polycarbonate is not very good. Compared to other materials, protrusions and small details may not turn out as well as using the same PLA.
According to Rigid.Ink, polycarbonate is mostly sold in clear. This 3D printing material has excellent heat resistance as well as impact resistance. But note that you will have to print at high temperatures. As mentioned above, it is better to use an enclosed 3D printer and a solid metal hotend.
Pros of polycarbonate : extra strong, excellent thermal and impact resistance.
Cons of polycarbonate : does not cope well with protrusions and small details of a 3D model, requires a body and an all-metal hot end, a limited number of colors.
Nylon
Next on our list of durable 3D printing materials is nylon. This material is considered by many to be the most reliable for desktop 3D printers. Nylon is inferior in strength to polycarbonate, but still clearly stronger than other competitors such as PLA and ABS.
Some numbers
A hook printed with nylon (910) thread had a breaking strength of 7,000 psi, while the same ABS hook only had a strength of 4,700 psi, according to Airwolf 3D. Airwolf 3D also noted that the nylon filament-printed clip holds 485 pounds.
MatterHackers posted similar results and noticed that a hook printed with their NylonX material can hold an average of 364 pounds before it breaks. Rigid.Ink also reviewed some nylon threads and gave them a four out of five rating for strength and a five for durability. For comparison: the strength and durability of PLA is three conventional units.
Nylon 3D printing
Nylon is slightly easier to print than polycarbonate, but it's still not PLA.
Nylon filament is quite hygroscopic, so it must be kept dry and requires a high printing temperature of 220-270°C. This material is prone to slight warpage, but is also resistant to impact, fatigue, and high temperature.
Nylon pros: impact resistance, fatigue resistance, heat resistance, easier to print than polycarbonate.
Nylon 9 cons0042 : hygroscopic, warping, very high hot end temperature required.
Composites
Finally, composite threads, although not essentially a single material, can be extremely strong. Composites are threads with certain additives that affect the properties of the material, including to increase strength. The names of these threads usually have the words "pro", "reinforced" (reinforced) or "infused" (infused), since they are usually a mixture of different materials.
For this reason, it is impossible to assess where the composite fibers are compared to the two previous materials. Some composites, such as Carbonyte, can compete with nylon threads for strength, while some composites are less durable.
It all depends on what the composite thread consists of. Durable is usually a high strength material such as nylon impregnated with another high strength material such as carbon fiber or glass.
Speaking of carbon fiber, this is also a very strong filament that is sometimes used for 3D printed bicycles. However, some composite fibers are stronger than many pure carbon fibers, so they are not in the top three, but deserve special mention as composite fibers.
Some numbers
We will use carbon fiber nylon and glass fiber nylon threads as examples. MatterHackers has determined that hooks printed on these materials can hold an average of 349and 268 pounds respectively.
Rigid.Ink gave the fiberglass nylon filament four out of five ratings for strength and five for durability. They also gave the carbon fiber nylon a five out of five rating for both strength and durability. In comparison, PLA and ABS were in the top three for strength.
3D printing with composites
Composites vary in the way they are 3D printed, but they are generally relatively similar to their base material.
Durable composite fibers are usually made from nylon, so you'll have to print at fairly high temperatures. These threads are also quite expensive.
Advantages of composites : This is a combination of several materials to achieve the best possible properties, durable.
Cons of composites: Expensive, requires high 3D printing temperatures.
90,000 strength of 3D printer products-Studia3D05/10/2018 in the expert blog, instructions
UDC 67.02, 620.172.2, 004.9
Study of the strength characteristics of the model material obtained by the FDM printing using ABS-plastic.
Kamonichkina Natalia Vladimirovna
Master of the 1st year N.E. Bauman
Supervisor: I.V. Kocheshkov
Candidate of Technical Sciences, Associate Professor of the Department of Materials Processing Technology”
Additive technologies are currently one of the most dynamically developing areas of "digital" production.
This type of technology has great prospects in the production of engineering products and repair work. Additive technologies are based on the use of 3D printers [1]. Of the seven basic principles of the 3D printing process noted in [1], today the most widespread is the extrusion of a material that is selectively fed through a nozzle or jet. This type of 3D printing in the technical literature is called FDM printing (Fused Deposition Modeling).
The widespread use of FDM printing is due to the relative cheapness of this type of 3D printers and wide technological capabilities in the production of various types of products. However, it cannot be argued that the strength characteristics of the material of parts obtained using FDM printing correspond to the strength properties of the material of the threads that are used in this case. The application of alternating layers by sequential deposition of filaments leads to the formation of a multilevel physical structure of the material.
The formed structure may differ in the anisotropy of properties relative to the direction of laying the threads, the difference in the thicknesses of the stacked layers, the presence of various types of defects, and the peculiarity of the mechanisms of material destruction. The factors listed above affect the strength characteristics of the resulting materials.
The most common materials for FDM printing are plastics. An example of a plastic commonly used in 3D printing is ABS plastic. Therefore, the purpose of this work is to study the strength characteristics of the material obtained by FDM printing using ABS plastic.
Description of the procedure and conditions for the preparation of samples.
The material obtained by FDM printing may have a different structure, but it will necessarily consist of a set of volumes with unidirectionally laid threads. This is determined by the technological features of the implementation of FDM printing. Therefore, in order to determine the strength properties of the material obtained by FDM printing, it is necessary first of all to study the strength of the model material with unidirectionally laid threads.
In order to evaluate the strength characteristics of the material and the anisotropy of the properties of the test, it is necessary to carry out tests along and across the direction of laying the threads.
The shape and dimensions of specimens for tensile tests were taken in accordance with GOST 11262-80 “Plastics. Tensile test method”. For research, a sample of the second type was chosen (Fig. 1). 3D printing was carried out using ABS+ plastic monofilament from StrimPlast, supplied according to the Specifications - TU 2291-001-24687042-2016. In accordance with these specifications, the monofilament must have a tensile strength of at least 47 MPa and printing must be carried out in the temperature range of 220-250 0 C.
Fig.1 Sketch of a specimen for tensile testing.
3D printing allows you to immediately produce samples for testing tensile strength, bypassing the stages of obtaining a primary blank and subsequent cutting of samples from it.
The thread laying order (G-code) was prepared in the Simplify3D version 4.0 program according to GOST 20999-83 “Numerical control devices for metalworking equipment. Coding information of control programs”, taking into account the location of the threads in the working part of the sample along or across the direction of stretching. FDM printing was carried out on a PicasoDesignerPro250 3D printer with an extruder nozzle diameter of 0.3 mm.
Before printing, to improve the adhesion of the material, the table was covered with a special The3D binder. The temperature of the table was 110 0 C, and the temperature of the extruder nozzle was 240 0 C. Printing was carried out in three modes:
- stacked layer of thread h sl =100 microns;
- Mode 2 : at extruder nozzle speed V s =45 mm/s and the thickness of the stacked layer of thread h sl =150 µm;
- Mode 3 : at the speed of movement of the extruder nozzle V s =60 mm/sec and the thickness of the stacked layer of thread h sl =200 µm;
The obtained specimens were tested for tension at the rate of extension of the clamps of the testing machine corresponding to 1±0.
5 mm/sec (the minimum rate of extension of the clamps of the testing machine provided by GOST 11262-80).
Discussion of the obtained experimental data.
Experimental data on the results of testing the material obtained by FDM printing using ABS, along and across the filament laying, are shown in fig. 2. From the presented data, it can be seen that the tensile strength of the material obtained by all three 3D printing modes in the direction of laying the threads is close in its values and is at the level of 31-33.5 MPa. If we use the manufacturer's data on the strength of the monofilament used in FDM printing (47 MPa), then these values are approximately 31% lower. However, in order to conduct a more correct comparison of the strength levels of these two materials, it is necessary to clarify to what extent the conditions for testing monofilaments coincide with the conditions for their loading in the model material.
The strength of the model material across the threads is much lower and depends more on the FDM printing modes (Fig.
2). The speed of movement of the extruder nozzle in combination with the thickness of the laid layer affect the adhesion strength of the threads. This is due to the spread of heat from the nozzle into the material. At high print speeds, less heat is transferred to the plastic at any given point in time than at low speeds. If you print a small layer at a low speed, then too much heat may be given off. This will increase adhesion, but there will be a possibility of defects in the form of plastic sagging. Conversely, if you are 3D printing with a thicker layer at high speed, there may not be enough heat to form good adhesion between the filaments.
This assumption is confirmed by the obtained experimental data (Fig. 2). In mode 1 (minimum printing speed and thickness of the stacked layer), the strength of the model material across the laying of threads is maximum and amounts to 20.2 MPa (67% of the material strength along the laying of threads), in mode 2 - 14 MPa (41% of the material strength along laying of threads) and in mode 3 - 15.
9 MPa (51% of the strength of the material along the laying of threads). That is, when switching from mode 1 to mode 2 of 3D printing, there is a decrease in tensile strength of samples with cross-laid filaments, as a result of a stronger influence of the increased thickness of the stacked layer of filaments than an increase in printing speed. And when switching from mode 2 to mode 3, the increase in printing speed has a predominant effect, which leads to a slight increase in the strength of the material (Fig. 2).
Fig. Fig. 2 Dependence of tensile strength σ р of the model material with longitudinal and transverse filament laying, obtained in different modes of 3D printing (Mode 1 – V s =30mm/sec, h sl =100 µm; Mode 2 – V s =45 mm/s, h sl =150 µm Mode 3 - V s =60 mm/s, h sl =200 µm have a different type of tensile diagram and fracture surface. If the tensile diagram of samples with transverse filament laying has a characteristic form for brittle fracture, then on the tensile diagram of samples with longitudinal fiber laying, after a slight decrease in the tensile force, after reaching a maximum, its gradual decrease is observed until the moment of sample failure.
Fig. 3 The nature of the destruction of samples with transverse (a) and longitudinal (b) laying of threads.
Samples with transverse fiber laying (Fig. 3a) have an absolutely flat fracture surface, while specimens with longitudinal fiber laying (Fig. 3b) have a developed fracture surface. When examining these fractures with an optical microscope, it can be seen that the destruction of the material with transversely laid fibers occurs in one plane (Fig. 4a) along the surface of the laid filaments. The fracture of the model material with the longitudinal laying of fibers (Fig. 4b) has a developed character. Fracture proceeds in different planes, and both areas of damage accumulation and flat zones characteristic of the main crack propagation are observed at the fracture.
Fig. Fig. 4 Fracture view of samples with transverse (a) and longitudinal (b) laying of threads.
Conclusion
- For the model material obtained by FDM printing using ABS plastic, when laying threads along the load application direction, no dependence of tensile strength on 3D printing modes was revealed.
The strength in all printing modes was 31-33.5 MPa, which is approximately 31% lower than the strength of monofilaments declared by the manufacturer. - The strength of cross-laid pattern material is 41-67% of the strength obtained when tested along the fibers. This strength depends on the modes of 3D printing. The maximum value - 20.2 MPa - was obtained in mode 1, at the speed of movement of the extruder nozzle V s = 30 mm/sec and the thickness of the stacked layer of thread h sl = 100 μm, and the minimum value - 14 MPa - is observed in the mode 2, at V c =30 mm/sec and h sl =100 µm.
- Samples of model material with longitudinal and transverse laying of threads have a different nature and type of fracture surface:
- during their transverse laying, an absolutely flat fracture surface is observed along the junction of the deposited threads, and, therefore, the amount of adhesion between them is the most important factor affecting the strength value;
- during their longitudinal laying, the fracture of the material has a developed character, both with areas of damage accumulation and with zones of main crack propagation.
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