Choosing the right 3D printer filament can have a big effect on how strong, durable, and high-performing your prints will be. Whether you’re making industrial prototypes, functional parts, or high-stress components, you’ll need to know which filaments offer the highest tensile strength and resilience. This guide will take a look at the strongest 3D printer filaments currently in existence, their unique properties and applications, and the best one to go for as per your project requirements. At the end of this review, you will understand what materials to use when designing for optimal strength without sacrificing productivity.
What Makes a Filament Strong?
Material composition, tensile strength, and resistance to environmental factors such as heat and impact determine the strength of a filament. High-strength filaments include polycarbonate (PC), carbon-fiber reinforced materials or nylon that do not deform or break when subjected to great strain. Important aspects involve strong connections between molecules chains and fillers which stiffen or soften for various uses. Determining the correct feedstock demands an understanding of both project mechanical requirements and its material properties.
Understanding Tensile Strength in 3D Printing
In 3D printing, tensile strength refers to the maximum stress that a printed material can bear before it breaks when stretched or pulled. This quality is important in determining how the material will function under forces in real-life applications. Tensile strengths of common materials, such as PLA and ABS, differ according to their compositions and printing conditions. PLA is more fragile but has some tensile strength, whereas ABS is tougher and suitable for applications requiring hard conditioning. Selecting a material with matching tensile strength as required by your project’s objective helps in achieving better results.
The Role of Durability and Toughness
When it comes to toughness and durability, what catches my attention is that the material must have the strength to cope with stresses and impacts without breaking. In terms of durability, it means that the material can withstand long-term usage or environmental exposure, while with respect to toughness, it is defined as its capability to absorb energy and resist fracturing. I will be able to make rational choices of materials based on these two attributes so they can match our project’s functional needs.
Factors Affecting Strength in Filaments
The strength of filaments is often assessed via tensile strength, fracture toughness, and several other factors. These are; material composition, extruder temperature, printing speed, and layer adhesion.
Material Composition
- The filament’s specific material significantly affects its strength. For instance, filaments made from high-strength materials like carbon fiber-infused polymers have higher tensile strengths compared to standard PLA or ABS. For example, carbon fiber PLA can have tensile strengths above 7000 PSI, whereas typical PLA ranges from 4000-7000 PSI. Material additives such as short fibers or nanoparticles may also improve some properties, including rigidity and thermal resistance.
Extruder Temperature
- Temperature settings for the extruder affect filament strength. The optimum temperature ensures that melting is done correctly, thus enabling efficient bonding between layers. It is usually 190-220°C for pla and 220-250°C for abs, respectively. Incorrect temperature settings can lead to weak bonds between layers, thereby reducing the structural integrity of the printed object.
Printing Speed
- Increasing the speed of printing can decrease the filament’s strength because it may not bond properly from one layer to another. When speed is reduced, there is a greater likelihood that there will be a better attachment between the two layers, thus reducing any gaps or weak points. A recommended speed for strength-printed objects is commonly 40-60 mm/s.
Layer Adhesion
- One of the principal determinants of a printed object’s overall durability is how well its layers stick together. Weak connections between layers result from inadequate adhesion and this leads to separations under loads. Layer height may need to be increased or heated beds used in order to improve adhesion. According to research, approximately 75% of nozzle diameter has been found to provide an optimum balance between surface finish and strength.
Post-Processing and Annealing
- Filament strengths could be further enhanced through processes like annealing. For instance, annealing specific PLA at temperatures around 80-110°C within certain time frames can increase its tensile strength by up to 40%. This results in recrystallization, which greatly increases the stiffness and long-lastingness of materials.
By understanding these factors and adjusting filament printing parameters appropriately, stronger and more dependable structures designed for various applications can be produced using 3D printers.
Types of 3D Printer Filament
Exploring Nylon Filament
Nylon filaments are widely used to make 3D prints because they are strong, resilient, and durable. This means it is highly resistant to impact stress and has high tensile strength for functional prototypes and parts that go through mechanical pressure. It is best suited for the manufacture of gears, hinges, or even other industrial tools since it has excellent wear resistance and low friction. However, it is very hygroscopic and, therefore, absorbs moisture from the air, which may affect printing quality. Therefore it should be stored in a dry place when not in use so as to give optimal performance with sometimes pre-drying required before using nylon filament.
The Benefits of Polycarbonate Filament
Polycarbonate filament is known for its excellent mechanical properties, which make it a favorite material for high-performance 3D printing. These are the main advantages of using polycarbonate filament:
- Great Mechanical Strength: It has got an approximate tensile strength of 60-70 MPa which can be said to be one of the highest among 3D printing materials. This makes it suitable to quickly produce functional prototypes, durable final parts and load bearing structures.
- Resistant to Impact: Consequently, this attribute allows printed articles to endure large loads and impacts without any major deformation or splitting. Its impact resistance is up to 850 J/m.
- Heat Resistance: When thermal stability is required, polycarbonate with a heat deflection temperature (HDT) of around 110°C – 115°C is perfect for such applications since this ensures that parts can function well in high temperature environments.
- Transparency: Polycarbonate also boasts excellent optical clarity that makes it a good choice where light is meant to be transmitted through or when transparency is needed; typical examples are lenses, protective covers.
- Flexibility and Toughness: In contrast with other brittle substances, polycarbonate has good flexibility, preventing it from breaking during stress. Thus, it may have a longer lifespan when used in various industries.
- Chemical Resistance: Polycarbonate is resistant to a wide range of chemicals, including oils and acids, hence broadening its functional range for industrial and chemical processing environments.
- Ease Of Post-Processing: Objects that have been formed with polycarbonate filament can easily be machined, sanded or painted which makes it more adaptable to any further customization.
When using polycarbonate filament, correct printer settings as well as environmental factors must be taken care of for optimum results. Most of the time, since it has a high melting point, it usually requires a heated bed and nozzle temperature at 250-300°C. In addition, enclosure chambers are recommended so that warping is minimized and print consistency maintained.
Understanding Carbon Fiber Filament
Carbon fiber filaments, consisting of chopped carbon fibers blended with a base polymer like PLA or nylon, are composite materials. These add to the filament’s strength and rigidity as well as its resistance to high temperatures, even though it is lightweight. In my case, when using carbon fiber filaments, I am always very careful so that they are compatible with my printer since the abrasive nature of these fibers can damage common nozzles; hence, hardened steel nozzles are preferable for this case. Additionally, I consider things such as a heated bed and moderate nozzle temperatures which help in improving adhesion and minimizing shrinking on completed parts so that they don’t become inaccurate.
Comparison: Nylon and Polycarbonate
Which Offers Better Heat Resistance?
Polycarbonate is better than nylon in terms of heat resistance because of its higher glass transition temperature (Tg) and superior thermal stability.
Glass Transition Temperature (Tg):
- Polycarbonate: This means that polycarbonate has a Tg of about 147°C (297°F), which implies it can withstand higher temperatures before softening.
- Nylon: Its Tg varies depending on the specific type, but it usually ranges from 50°C to 70°C (122°F to 158°F), meaning that compared to polycarbonate, it possesses poor resistance against heat.
Melting Point:
- Polycarbonate: Polycarbonate does not have a sharp melting point; instead, it maintains structural integrity up to its decomposition temperature, which is around 267°C (513°F).
- Nylon: It melts at a range of between 190°C and 266°C (374°F to 511°F), depending on the grade. Nevertheless, long-time exposure to high temperatures can degrade its performance.
Thermal Deformation Resistance:
- Polycarbonate: Exhibits minimal deformation under heat – this makes it suitable for applications that require constant dimensional stability even at elevated temperatures.
- Nylon: Even though nylon can tolerate moderate thermal conditions well, it tends to deform more easily than polycarbonate when subjected to extended periods of heating.
Applications in High-Temperature Environments:
- Polycarbonate: These include automotive and aerospace industries where materials experience high operating temperatures so; commonly used in such areas.
- Nylon: Despite its average resistance to heat, nylon is commonly used because it is flexible and can resist impacts well but not for its thermal properties.
On the other hand, a better option would be polycarbonate, which exhibits stronger thermal aspects and higher degradation resistance at higher temperatures in case of high heat resistance.
Evaluating Impact Resistance
Materials utilized in industries where mechanical durability and safety are of utmost importance, need to possess impact resistance. This is the capacity of a material to absorb energy and not undergo deformation or fracture suddenly under mechanical stress. Characterized by the impact tests that determine their applicability in different uses.
- Polycarbonate: Polycarbonate, on its part, is widely known for its superior strength, yet it records an impact strength of around 850-950 J/m as measured using the Izod test method. The Significance is that such materials have applications in gears and bearings and applications requiring resilience combined with light loads.
- Nylon: Nylon has good overall strength, although it has lower impact resistance compared to polycarbonate, usually ranging from about 100-150 J/m. This makes it more appropriate for applications needing lightness combined with some flexibility as in cases of gears and bearings.
- Acrylics: Acrylics are characterized by clarity and rigidity but possess low levels of impact resistance which may be as low as five times less than that possessed by polycarbonates. It is therefore reserved for instances where aesthetics supersedes mechanics like display cases or signage.
The performance of polycarbonate ultimately surpasses that of nylon and acrylic in terms of impact resistance making it the most suitable material for environments with a high stress application. This means that polycarbonate continuously shows its dominance over other materials in terms of impact tests done under various conditions. By understanding these properties, engineers are able to choose materials that can specifically satisfy every requirement.
Applications in Prototyping
The exceptional mechanical properties and versatility of Polycarbonate are crucial in prototyping. Here are some applications of polycarbonate in prototyping with relevant data:
Structural Prototypes
- Impact-resistant and durable structural prototypes can be made using polycarbonate. These prototypes are usually tested thoroughly to replicate real world scenarios. For example, the material has an impact resistance of 850 J/m thus it can be relied on when assessing product performance under stress.
Transparent Functional Components
- Superior optical clarity means that transparent components like covers and lenses can be produced from this material. For light transmission and visual accuracy tests, such prototypes depend on the 88%-92% transparency rate of polycarbonate that allows for excellent visibility without compromising strength.
Snap-Fit Connections and Moving Parts
- Polycarbonate is often used in prototypes that feature snap-fit designs or moving parts because it is elastic and non-brittle. Its flexibility enables it to bend instead of breaking thereby making it suitable for disassembly as well as reassembly of components during trials.
Electronics Enclosures
- Prototyping electronics enclosures which must be both heat tolerant, electrical insulating, structurally sound, is best done with Polycarbonate. It has a temperature range of -40°C to 115°C so as to perform reliably across a variety of electronic uses.
Models for Aerospace and Automotive
- Polycarbonate is used in aerospace and automotive industries to develop prototypes for aerodynamic testing and structural validation, and it is light but strong. Designers can lessen the weight of their designs while still keeping them strong due to its density at around 1.2 g/cm³.
Prototypes made from 3D Printing
- In 3D printing polycarbonate filaments are used for creating high-performance prototypes. It has a high melting point (267°C) and is dimensionally stable thereby allowing the production of complex, accurate parts suitable for demanding test environments.
By using polycarbonate’s unique features engineers are capable of developing prototypes that match strict application criteria which enhance reliability and functionality of final products during development phases.
How to Choose the Strongest 3D Printer Filament
Considering 3D Printing Materials Available
In selecting the most powerful 3D printing filament, you should consider these materials:
Polycarbonate (PC)
- With its high impact resistance and durability, polycarbonate is ideal for applications that require toughness and heat resistance.
Nylon
- This material offers good flexibility, strength, and wear resistance that makes it suitable for functional parts like gears or hinges.
Carbon Fiber Reinforced Filaments
- They bring together strength with rigidity to provide a lightweight option for applications where reduced weight and high stiffness are critical.
To get the best performance out of your selection, you need to assess the specific requirements of your project, such as mechanical stress, environmental exposure, intended use, etc.
Matching Filament Strength to Your Project Needs
When assessing filament strength for your project, it is important to take into account different materials’ mechanical properties, including tensile strength, flexural modulus, and impact strength. Below are the key metrics-based comparisons of some popular 3D printing filaments:
Polycarbonate (PC)
- Tensile Strength: Approximately 70 MPa.
- Flexural Modulus: Around 2,200 MPa.
- Impact Resistance: High, with excellent resistance to sudden shocks and fractures.
It is advisable that when one intends to come up with parts that can carry heavy loads or materials that can withstand very high temperatures such as protective casings or high-strength prototypes one should use polycarbonates.
Nylon
- Tensile Strength: Ranges from 40 MPa to 78 MPa (depending on the blend).
- Flexural Modulus: Approximately 1,600 MPa.
- Impact Resistance: Good, with impressive wear resistance.
Components under repetitive motion or abrasion, like industrial gears or bearings, make nylon an ideal material of choice here.
Carbon Fiber Reinforced Filaments
- Tensile Strength: Varies from 50 MPa to 110 MPa.
- Flexural Modulus: Extends up to 6,000 MPa depending on the polymer base.
- Impact Resistance: Moderate, with excellent rigidity.
These lightweight yet strong structures make these filaments well-suited for aerospace, automotive, and performance-driven applications.
PLA (Polylactic Acid)
- Tensile Strength: Approximately 60 MPa.
- Flexural Modulus: About 3,500-4,000 MPa.
- Impact Resistance: Poor susceptibility to brittle fractures.
Due to its user-friendliness and biodegradability which enables it to be used in low-stress applications like prototypes and decorative models.
ABS (Acrylonitrile Butadiene Styrene)
- Tensile Strength: Approximately 40 MPa.
- Flexural Modulus: Around 2,000 MPa.
- Impact Resistance: Depending on the mixture, from medium to high.
ABS is a hardy filament for end-part uses, particularly where moderate durability and impact resistance are required.
While selecting filaments, one should remember that one has to align the specific mechanical properties with what is required for the project. For example, tensile strength is essential in load-bearing components, while impact resistance plays a major role in those items that undergo heavy shocks. By conducting a thorough analysis of material properties against performance criteria, it is possible to achieve efficiency as well as longevity on your 3D-printed designs.
The Importance of Temperature Resistance
One of the key aspects that determine the right 3D filaments is temperature resistance because it shows how materials can perform under thermal stress and still maintain their properties. Therefore, heat resistance is critical for high temperature applications to ensure structural integrity as well as functionality.
For instance, Polycarbonate (PC) has elevated HDT of about 135°C making it a reliable choice for products subjected to continuous heating such as automotive parts and industrial components. Also, Polyetheretherketone (PEEK) demonstrates exceptional temperature resistance up to 250°C, so it is commonly used in aerospace and medicine owing to its stability and durability even at extreme conditions.
In contrast, some commonly used filaments like PLA have lower heat resistant values characterized by HDT of around 60°C. Hence, they cannot be applied when materials are exposed to high temperatures or else they will deform or fail with time. In contrast ABS seems like a moderate solution because its HDT is approximated at almost 100°C thereby making it versatile enough for application where slightly higher temperatures are involved.
Optimal performance can only be achieved by having a good sense of the thermal properties of your material. For instance, introducing filaments such as PETG with HDT around 75°C for consumer-grade projects would strike a balance between ease of use and moderate heat resistance. In the long run, it is imperative to critically examine these qualities, especially in scenarios where products are used in extreme temperatures or conditions so that they can last longer.
Enhancing the Strength of 3D Printed Parts
Best Practices for Printing Strong Parts
Key practices to be followed in order to strengthen parts produced from 3D printing are as follows:
Optimize Print Orientation
- Print orientation plays a critical role in determining the strength of the finished part. Aligning the layers such that they cause minimum stress on the weakest axes (the point at which two layers bond is usually weak) is crucial.
Increase Wall Thickness
- The incorporation of thicker walls enhances the strength and durability of components. Ensure that the wall thickness used meets mechanical requirements.
Adjust Infill Density and Pattern
- Higher infill densities and stronger patterns, e.g., grid or triangle, should be used for applications with improved structural integrity.
Select Appropriate Materials
- Strength is directly influenced by material selection. Use nylons for high strength or polycarbonates, and use PETG/ABS for balanced durability.
Fine-Tune Printing Settings
- Enhancing layer bonding by reducing layer height and controlling print speed to prevent imperfections that weaken strength.
These practices will help you achieve better mechanical performance and reliability in your 3D-printed parts.
The Impact of Printing Process and Settings
Determining the properties and quality of 3D printed parts depends on the printing process itself. These components’ final performance depends on factors such as print orientation, cooling rate, and nozzle temperature, among others. For example, optimum material flow and layer adhesion can be attained by maintaining correct nozzle temperatures. Certain materials like PLA typically operate at a temperature range of 190–220°C while high-performance materials such as polycarbonate might require above 250°C.
Cooling and Layer Bonding: Rapid cooling may lead to warping or weak layer adhesion, particularly in materials prone to shrinkage, such as ABS. Controlled cooling settings or heated print chambers can minimize these defects, providing uniform layer solidification.
Print Orientation and Strength: The orientation of the print influences anisotropic strength—parts are often weakest at the layer interface. Printing critical components in orientations that align with anticipated stress loads significantly increases durability. For instance, experiments have shown that tensile strength could be increased by up to 25% by optimizing orientation.
Effect of Speed and Layer Thickness: Changing the print speed is yet another vital point. This often gives rise to stronger pieces as a result of better bond between layers, while smaller layer heights (e.g., 0.1–0.2 mm) give way to more detailed resolution and better surface finishes. Nevertheless, there exists a trade-off with increased production time which must be weighed against project objectives.
Through systematic analysis and optimization of these variables, it is achievable to enhance mechanical strength, dimensional accuracy, and aesthetic appeal of 3D-printed components for demanding application purposes.
Using Enclosures for High-Temperature Resistance
To stabilize the printing environment and maintain consistent material performance when working with high-temperature materials such as ABS or polycarbonate, enclosures are necessary. They help to keep the ambient temperature high, thereby reducing incidences of warping, cracking, or even layer separation due to sudden cooling during the process of printing. Besides, they safeguard the inner parts of the printer from external temperature variation. It is recommended that enclosures be made using heat resistant materials and incorporate appropriate fumes management systems as well as thermal stability.
Frequently Asked Questions (FAQs)
Q: Which filament is the strongest when considering the use of a 3D printer?
A: Several filaments come to mind when talking of their strength in 3D printing, however, Polycarbonate (PC) filament is usually considered the strongest for FDM 3D printing and peeks filaments follow right behind. Other strong options include ABS, PETG and Nylon as well. However the strength can change depending on the type of application and what type of strength is required (tensile, impact or flexural).
Q: How does the PETG filament compare to ABS in the context of strength.
A: In considering the two filaments, it is widely accepted that PETG filament is stronger as well as more durable than the ABS filament. This is because PETG provides superior adhesion of the layers and, as such, is less prone to warp due to high impact strength. On the other hand, in terms of heat resistance and post-heating capabilities, ABS has the upper hand. Nevertheless, both of the filaments are great for applications where the projects need to be durable.
Q: Which filament provides the best tensile strength for a 3D printer during everyday prints?
A: While using a 3D printer for daily tasks, many recommend PETG; it has its prominent characteristics of being long-lasting, flexible, and even having a concrete impact resistance, which helps during the printing process, but the filament itself is durable, resistant to moisture while being applicable for both indoors and outdoors. It is a reliable option that helps in maintaining a general strength during a 3D print while also making it easier to print.
Q: What can I do to enhance tensile strength in my 3D print components?
A: If there are ways to enhance the strength of 3D printed parts further, then they are: 1. Consider using filaments stronger than the ones being currently used .2. Alter the settings on prints to achieve effective adhesion.3. Raise the percentage of infill. 4. Composite filaments that have been reinforced with carbon fibers.5. Orientation of the part to be optimized. 6. Treating the components with heat or coating post-processing. 7. Increase the print temperature to enhance layer bonding.
Q: What does TPU filament refer to, and how does it compare with other stronger filaments?
A: TPU, or thermal plastic polyurethane as it is called in full, is an elastic and flexible filament material. When compared to other filaments, it is strong however lone for producing tensile strength, TPU has an extensive impact resistance capacity and is durable. Moreover, the material has a high resistance to abrasion and is able to withstand compressive and bending forces repetitions which makes it the perfect option for application requiring flexibility and resilience rather than rigid strength.
Q: What are the Limits of the Strongest 3D Printer Filaments?
A: Yes, there are some drawbacks to using the strongest 3D printer filaments. For starters, one drawback is the high banking temperatures and the need for specialist devices. Other strong materials such as PC and PEEK are tough but can warp, and require being encased when being printed. In addition to being more expensive than conventional filament, it is pricier than PLA filament. They’re made of Materials that are harder to work with, making post-processing and finishing tougher.
Q: What role do carbon fiber reinforced filaments play in improving the strength of 3D printed components?
A: Three-dimensional carbon printed parts have increased strength owing to utilizing carbon fiber reinforced filament since the components manufactured from it have mixed carbon fibers with other base filaments such as PETG, Nylon, and ABS, thereby enhancing their properties. Moreover, the mix enables the achievement of higher tensile strength, improved rigidity, and increased dimensional stability of the fibers, making it suitable for functional, lightweight prototypes and end-use parts tailored to one’s specifications. When it comes to 3D printing, carbon fiber filaments can be used as a replacement for nylon and glass-filled polymers owing to their impressive usability.
Q: What exactly is PEEK filament and for what reason is it deemed as one of the most durable types of filament for 3D printers?
A: As a result of its versatility, toughness, stability, and high-temperature properties, PEEK (Polyether Ether Ketone) is widely regarded as one of the strongest thermoplastics on the market and is, therefore, incredibly popular among aerospace and medical industries. This type of filament is suitable for 3D printers because it has a high tensile strength, is durable, has a wide operating temperature range, and has superior chemical properties. However, it can only be utilized by professional-grade 3D printers since it requires higher operating temperatures than normal printers.
Reference Sources
1. FDM 3D Printing Materials: Understanding Their Mechanical Properties
- Authors: Warnung, L., et al.
- Publication Date: 14th December, 2018
- Journal: RTejournal – Fachforum für Rapid Technologien
- Key Findings:
- The investigation was focused on the mechanical properties of eight different material types employed in FDM.
- Polyamide filament is the strongest of the materials tested, but polyethylene terephthalate reinforced with carbon fibers has the highest stiffness.
- The authors point out that for printed materials to have certain mechanical characteristics, the manufacturing process must be followed properly.
- Methodology:
- Comparisons can be made between tensile strength and other mechanical properties of materials by conducting tests based on global standard EN ISO 527-1 (Warnung et al., 2018).
2. Tensile and Fatigue Analysis of 3D-printed Polyethylene Terephthalate Glycol
- Authors: Grzegorz Dolzyk, Sungmoon Jung
- Publication Date: 26th March 2019
- Journal: Journal of Failure Analysis and Prevention
- Key Findings:
- This study investigates the tensile and fatigue properties of PETG that allow its use in diverse contexts.
- However, results show that PETG’s performance differs significantly depending on printing parameters, although it has good mechanical properties.
- Methods:
- The material’s behavior in different loadings was assessed through tensile tests and fatigue analysis (Dolzyk & Jung, 2019, pp. 511–518).
3. Tensile Properties of Fibre-Reinforced Additive Manufacturing and Fused Filament Fabrication Investigations
- Authors: Yolnan Chen et al.
- Publication Date: June 5, 2020
- Journal: International Journal of Rapid Manufacturing
- Key Findings:
- According to the study, the impact of fiber orientation on the strength of parts made by FRAM was investigated.
- The results indicated that certain fiber orientations greatly improve tensile strength, with concentric ring patterns giving the best outcomes.
- Methodology:
- This involved subjecting different specimens with varying fiber orientations to various tensile tests. Their findings were also analyzed to establish the best strength configurations for them (Chen et al., 2020).
4. Development And Characterization Of A Short Banana Fiber—PLA Filament For 3D Printing
- Authors: Mohamed Shafeer P.P et al.
- Publication Date: May 13, 2024
- Journal: Polymer Composites
- Key Findings:
- Therefore, this research project developed a composite filament using short banana fibers and polylactic acid (PLA), which even though its tensile and flexural properties were reduced compared to pure PLA still had acceptable performance for non-structural applications.
- Thus, this investigation reveals that there is a potential improvement in sustainability of materials used in three dimensional printing through natural fibers use.
- Methodology:
- The filament was made from a single screw extruder, and different blending methods were employed to evaluate the mechanical and thermal properties (P.P. et al., 2024).
5. Mechanical Test-Based Optimization of Acrylonitrile Butadiene Styrene Filament 3D Printing Process Parameters
- Authors: R. S, R. N.
- Publication Date: April 1, 2023
- Journal: International Journal of Mechanical and Industrial Engineering
- Key Findings:
- The research aimed to enhance print parameters for ABS filament so that optimum mechanical properties can be achieved.
- It was found that specific adjustments to extruder temperature, layer height and printing speed have significant effects on tensile strength of printed parts.
- Methodology:
- The authors produced tensile specimens according to ASTM D638 standards, and results were analyzed towards ideal printing settings (S & N., 2023).
6. 3D printing
7. Nylon
