Introduction

Composite and plastic fasteners are increasingly essential components in modern engineering assemblies. These fasteners – which include screws, bolts, nuts, washers, and specialized connectors made from polymer materials or fiber-reinforced composites – offer a unique blend of properties for demanding applications. In situations where lightweight construction, corrosion resistance, and electrical insulation are critical, plastic-based fasteners have become a strategic choice rather than a compromise.

Engineers across aerospace, electronics, automotive, medical, and other industries are turning to composite and plastic fasteners to achieve significant reductions in weight, eliminate corrosion issues, and meet specialized performance requirements. This report provides an in-depth analysis of the technical performance characteristics of composite and plastic fasteners, examines their cost-effectiveness in manufacturing and sourcing, explores their suitability for various industry applications, and reviews the common engineering polymer materials used for fasteners along with their key properties.

Technical Performance Characteristics

Plastic and composite fasteners exhibit a range of technical performance characteristics that can meet demanding engineering specifications. Key aspects of their performance include mechanical strength, durability under cyclic loads, thermal stability, environmental resistance, and electrical properties.

Mechanical Strength and Durability

Modern engineering polymers and composite materials can achieve impressive mechanical strength in fastener applications. Unreinforced thermoplastic fasteners (such as those made of nylon or acetal) typically have tensile strength on the order of tens of MPa, often around 50–80 MPa for common grades of these plastics. By incorporating fillers or fibers (e.g. glass or carbon fibers) into the polymer matrix, the strength can be dramatically increased – glass-filled nylon or PEEK fasteners can reach tensile strengths in the 150–200 MPa range or higher. In the case of fully fiber-reinforced composite fasteners (for example, pultruded glass fiber or carbon fiber composite bolts), tensile strength can reach several hundred MPa (even exceeding 500 MPa in some designs), which is exceptionally high for a fastener and comparable to the strength of many structural materials. This high strength-to-weight ratio is one of the major advantages of composite fasteners, allowing them to handle substantial loads while remaining extremely lightweight.

Plastic fasteners also tend to have good toughness and vibration damping characteristics. Polymers like nylon are relatively flexible and can absorb shocks or vibrations without cracking, which helps in applications where fasteners experience dynamic loads. Many plastic fasteners exhibit excellent fatigue resistance under repeated stress cycles – for instance, a well-designed composite (FRP) bolt can endure millions of load cycles at moderate stress levels without significant loss of integrity. However, it is important to consider creep and stress relaxation: under sustained loads or elevated temperatures, thermoplastics can slowly deform. Engineers must account for creep by not overstressing plastic bolts and by selecting high-performance polymers (such as PEEK or polyimides) or adding fiber reinforcement if long-term dimensional stability under load is needed.

Thermal Stability and Heat Resistance

The thermal properties of plastic fasteners vary widely with material. Standard engineering plastics have moderate heat resistance, while advanced polymers and composites can withstand very high temperatures. Operating temperature limits for common fastener plastics range from about 100 °C for materials like general-purpose nylon or polypropylene, up to approximately 150 °C for polyvinylidene fluoride (PVDF), and around 200 °C for polyphenylene sulfide (PPS). High-performance polymers push these limits further: PEEK (Polyether Ether Ketone) fasteners remain mechanically stable up to roughly 250 °C (continuous service), and specialized polyimides (such as Vespel®) and polyamide-imides (PAI, e.g. Torlon®) can operate in the 250–300 °C range. Thermoset or composite fasteners using heat-resistant resin systems (like epoxy or cyanate ester with fiberglass or carbon fiber reinforcement) can also tolerate temperatures around 150 °C or more, and ceramic-based fasteners (though technically not plastic) can go much higher for extreme environments.

It is noteworthy that as temperature rises, the strength and stiffness of polymer fasteners generally decrease. Engineers should check the heat deflection temperature or glass transition temperature (T_g) of the chosen polymer, as exceeding these can lead to loss of rigidity or accelerated creep. Many polymers also become brittle at very low temperatures, but engineering plastics like nylon, POM, and PEEK typically remain tough down to -50 °C or below, making them suitable for cold environments. Thermal cycling can be an important consideration – plastic fasteners have higher coefficients of thermal expansion compared to metals or ceramics, which means they expand and contract more with temperature changes. In design, allowance for thermal expansion is necessary to prevent loosening or stress buildup in joints that see large temperature swings.

Chemical, Corrosion, and Environmental Resistance

Corrosion resistance is a defining advantage of plastic and composite fasteners. Polymers do not rust or oxidize, and they are generally immune to salt spray and most common environmental chemicals. This makes plastic fasteners ideal for outdoor use, marine environments, and corrosive industrial settings. For example, fiber-reinforced plastic bolts have been shown to survive decades in saltwater or chemical plant conditions with minimal degradation.

Different polymers offer resistance to different chemicals, so material selection is important. Nylon (polyamide) fasteners resist fuels, oils, and many solvents, but can be attacked by strong acids or bases and will absorb moisture from the air (which in high humidity can slightly reduce nylon’s mechanical strength and cause dimensional changes). Acetal (POM) is highly resistant to water and hydrocarbons and does not absorb water significantly, making acetal screws a good choice in wet conditions or when dimensional stability is needed in humidity. PPS and PVDF are outstanding in harsh chemical environments: PPS resists a broad range of solvents, acids, and bases even at elevated temperatures, while PVDF (a fluoropolymer) is nearly impervious to strong acids, chlorine, and most organic solvents. PTFE (Teflon) fasteners, though lower in strength, offer perhaps the ultimate chemical resistance – they can endure exposure to almost any chemical (even highly aggressive acids like hydrochloric or hydrofluoric acid) without corroding or degrading. Fluoropolymer fasteners (PTFE, PFA, PVDF) are therefore commonly used in chemical processing equipment, semiconductor manufacturing (where high purity and chemical resistance are essential), and anywhere that ordinary metal hardware would quickly corrode.

Environmental factors such as UV exposure and weathering can affect plastic fasteners over time. Some plastics like PVDF and PTFE have excellent UV stability and can be used outdoors for long periods without significant property loss. Others, like untreated nylon or polypropylene, can degrade under prolonged sunlight (becoming brittle or discolored) unless they are UV-stabilized with additives. Many commercial plastic fasteners intended for outdoor use are formulated with UV inhibitors or are made from inherently UV-resistant resins. Moisture and water pose no corrosion threat to plastics, but as mentioned, hygroscopic materials (notably nylon) will absorb water and should be used with caution in applications where water uptake could loosen the fastener or alter its dimensions. Overall, plastic fasteners can be trusted in humid, wet, and chemically aggressive environments that would be extremely challenging for traditional metallic hardware – providing reliable performance with no need for protective coatings or fear of rust.

Electrical and Magnetic Properties

Plastic and composite fasteners are electrically insulating and non-magnetic, which opens up applications where conductive fasteners are unsuitable. The electrical insulation property (high dielectric strength and volume resistivity) of polymers means plastic screws and bolts can secure components in electrical assemblies without creating undesired conductive paths. This is critical in electronics and power systems – for instance, nylon or PVC screws are often used on circuit boards, in electrical enclosures, and on terminals to prevent short circuits. Fasteners like these typically have a dielectric strength on the order of 10–20 kV/mm, providing excellent insulation even in high-voltage environments. Fiber-reinforced composite fasteners also retain insulation properties (glass and aramid fibers are non-conductive; note that carbon fiber is slightly conductive, so glass-fiber composites are preferred when true electrical insulation is needed).

In addition to being non-conductive, polymer fasteners are transparent to electromagnetic fields and do not interfere with magnetic or RF-sensitive equipment. This characteristic is invaluable in applications like MRI machines, radar and antenna systems, and aerospace electronics, where the presence of metal fasteners could cause electromagnetic interference or distortion of signals. Plastic fasteners produce no magnetic signature and do not induce eddy currents or galvanic coupling in assemblies, thereby preserving the intended electromagnetic environment. For example, using plastic hardware around sensitive magnetometers or antennas ensures that the fasteners themselves do not become unintended antennas or magnetic disturbance sources. The non-conductive nature of these fasteners also means they avoid creating galvanic corrosion cells in mixed-material joints, which is an added reliability benefit in electrical and electronic systems.

Weight and Density Advantages

One of the most compelling performance benefits of composite and plastic fasteners is their lightweight nature. Polymers have densities in the range of roughly 1.2–2.0 g/cm³ (many common engineering plastics are around 1.3–1.5 g/cm³), making them extremely lightweight materials. This low density can translate to significant weight savings in assemblies. In designs that use hundreds or thousands of fasteners, switching to plastic can cumulatively save several kilograms of mass. Such weight reduction is critical in weight-sensitive projects, contributing to improved fuel efficiency in vehicles and aircraft and better performance in moving or rotating machinery. Moreover, the lower inertia of plastic parts can reduce stress on assemblies that experience vibration or dynamic loads. Essentially, composite and plastic fasteners enable engineers to meet strength requirements with significantly less weight, enhancing the overall efficiency and responsiveness of the system.

Other Performance Considerations

Plastic fasteners have a few other notable performance characteristics. Many polymers are non-abrasive and have low friction coefficients, meaning a plastic screw is less likely to gall or damage mating threads. This is useful in applications requiring repeated assembly and disassembly, as polymer threads will not seize or cold-weld as some metals do. Materials like acetal and PTFE are particularly low-friction, acting almost self-lubricating in threaded or sliding contact. Some polymer fasteners are also inherently quiet in operation – for example, plastic clips and rivets in automotive interiors eliminate rattling noises that metal parts might create, contributing to a quieter and more refined product. Additionally, plastics can be formulated to be flame-retardant or self-extinguishing to meet fire safety requirements. For instance, polyetherimide (PEI) and certain flame-resistant grades of nylon or PEEK are rated UL94 V-0, meaning they will not sustain burning and will self-extinguish quickly. This property is crucial for fasteners used in electronics, aerospace interiors, or any application where fire safety is a concern. Finally, it’s worth noting that the anisotropy of composite fasteners (those with oriented continuous fibers) can be both a design benefit and a challenge: they exhibit different strength and stiffness in different directions, so proper orientation and engineering are needed to fully exploit their capabilities without encountering weak axes.

Cost-Effectiveness in Manufacturing and Sourcing

Beyond performance attributes, composite and plastic fasteners often offer significant cost advantages in both manufacturing and life-cycle terms. Manufacturing cost-effectiveness stems from the efficiency of plastic processing methods and the economies of scale in high-volume production. Most plastic fasteners are produced by injection molding, a process that can turn out thousands of pieces per hour once a mold is created. The initial investment in a precision mold can be high, but the per-unit cost of injection-molded fasteners is extremely low – often on the order of a few cents or less for simple designs in commodity plastics. Injection molding is a fast, high-volume production method, so plastic fasteners lend themselves to very cost-effective mass production.

The raw material cost of plastics varies: common polymers like polypropylene, polyethylene, or nylon are inexpensive per kilogram, whereas high-performance polymers like PEEK or polyamide-imide are more costly. Even so, since plastic fasteners are lightweight and use relatively little material per part, the overall material cost per fastener remains low. For applications that demand advanced polymers, the cost is typically justified by the performance benefits (for example, using a $100/kg high-grade polymer can be reasonable if only a few grams of material are needed per fastener to enable a crucial function). Additionally, plastic fasteners do not require any plating or anti-corrosion surface treatments, which simplifies the supply chain and eliminates secondary finishing costs that would be necessary for corrosion-prone metal fasteners.

In terms of sourcing, plastic fasteners are widely available through industrial suppliers and catalogs. Standard sizes (metric and imperial threads, various head styles) can be readily obtained in materials like nylon, acetal, polycarbonate, PPS, PEEK, and others. Because many industries have adopted polymer fasteners, there is a competitive market with multiple manufacturers, which helps keep prices reasonable and lead times short for common items. For specialized composite fasteners (like pultruded fiberglass bolts or very high-end polymer screws), the supplier base is more limited, but these are often custom-specified parts in high-value applications where the cost is offset by the unique problem-solving benefits (for instance, eliminating corrosion in a chemical plant or saving weight on a spacecraft component).

Another aspect of cost-effectiveness is installation and maintenance. Plastic fasteners are generally easier to handle due to their lighter weight and often do not require special lubricants or anti-seize compounds during installation. They also typically do not gall or strip threads as easily when properly tightened, reducing the risk of damage during assembly. In service, the longevity of composite fasteners in corrosive or fatigue-prone environments means fewer replacements over time, translating to lower maintenance costs. For example, using composite hardware on outdoor structures can cut down the frequency of inspections and part replacements that would be needed if corrosion were a concern. In high-volume consumer products (like electronics or appliances), employing an inexpensive molded plastic screw instead of a more complex multi-part insert or metal hardware can simplify assembly and allow for automated installation, further driving down production costs.

For prototyping and low-volume needs, plastic fasteners can even be 3D printed or CNC-machined from plastic rod stock with relative ease, enabling quick turnaround for unique designs. This flexibility in manufacturing means that development costs can be kept low, and designs can be iterated without investing in hard tooling until a final design is verified. Once in production, the ability to mold complex shapes allows integration of features (like captive washer heads, snap-fit clips, or custom drive recesses) at no additional unit cost – features not easily achievable with standard off-the-shelf metal fasteners.

In summary, when the total cost picture is considered – including production, materials, assembly, and maintenance – composite and plastic fasteners often provide a highly cost-effective solution for the appropriate applications. They leverage mass-production techniques, reduce the need for secondary finishing or replacement due to corrosion, and contribute to longer service life in harsh conditions, all of which offer economic benefits alongside their technical advantages.

Applications in Various Industries

Thanks to their diverse properties, composite and plastic fasteners are used across a wide range of industries. Different sectors capitalize on the unique benefits of polymer fasteners – whether it’s weight savings, insulation, chemical stability, or simply cost and convenience. Below are some key industries and examples of how plastic fasteners are applied in each:

Aerospace and Defense

The aerospace industry was an early adopter of high-performance plastic and composite fasteners to achieve critical weight reductions and performance gains. Aircraft use thousands of fasteners, and many interior and secondary components now use plastic hardware to save significant weight. For instance, nylon and acetal screws secure avionic equipment, interior panels, and cabin fittings, where their non-magnetic and non-corrosive nature ensures reliability over the aircraft’s service life. In military and defense applications, plastics are also valued for their radar transparency – polymer fasteners on antennas or stealth structures do not reflect radar signals, preserving the desired low-observable profile and sensor accuracy.

In spacecraft and satellites, where every gram matters and materials face extreme conditions, polymer fasteners like PEEK, polyimide, or advanced composite bolts are often used. They provide the needed strength while being much lighter than comparable metal hardware, and importantly, they can tolerate the vacuum of space without outgassing (which could contaminate sensitive instruments). PEEK fasteners, for example, are commonly found in satellite cable mounts and optical bench assemblies because of their excellent dimensional stability across –150 °C to +150 °C and their high resistance to radiation. Composite fasteners are also used to join carbon-fiber structural panels on spacecraft, preventing galvanic corrosion issues that can arise with traditional metallic fasteners in carbon composite structures. The non-conductive nature of these fasteners eliminates any chance of creating unintended electrical grounding paths on satellites. Additionally, aerospace fasteners must meet stringent flame-smoke-toxicity requirements for aircraft interiors – materials like PEI (Ultem) and certain flame-retardant grades of nylon are chosen for seat and cabin fasteners because they self-extinguish and emit very low smoke if exposed to flame.

Automotive and Transportation

In automotive engineering, plastic fasteners have become ubiquitous, appearing in applications from the engine compartment to the vehicle interior. The ongoing push to improve fuel efficiency and increase electric vehicle range compels automakers to reduce weight wherever possible, and one strategy is the widespread use of plastic clips, brackets, and screws throughout the vehicle. Plastic fasteners are now found in countless automotive applications, helping to trim the weight of wiring harnesses, body panels, and interior assemblies without sacrificing functionality or durability.

Nylon push rivets and clips hold car bumpers, splash guards, and interior trim panels in place. These fasteners flex and snap in, providing secure attachments that also simplify assembly (often requiring no tools for installation on the production line). Under the hood, where temperatures can be high, materials like heat-stabilized nylon, PPS, or high-temp polycarbonate are used for fasteners and cable ties that secure hoses, wiring, and other components. They survive exposure to engine oils, coolants, and continuous operating temperatures that may reach 120–150 °C. For example, PPS screws or inserts might be found in assembling an engine intake or sensor module, due to PPS’s ability to retain strength and dimensional stability in hot, chemically aggressive environments.

Electrical insulation is another reason plastics are used in vehicles – with the rise of electric vehicles (EVs), many high-voltage components require non-conductive fasteners. Plastic nuts and bolts secure battery pack enclosures, power electronics housings, and high-voltage cable connections, ensuring there is no risk of shorting or arcing to the vehicle chassis. The non-magnetic property of polymer fasteners is also beneficial for vehicles equipped with compasses or magnetic sensors; using non-metallic fasteners in such cases prevents interference with sensor readings and electronic control systems.

The rail and mass transit sectors similarly use polymer fasteners in interior carriage assembly (seats, panels, lighting fixtures) and in electrical systems on trains where insulation and light weight are desired. The vibration environment in transportation is intense, but plastic fasteners that are properly designed (with integrated locking features or self-tapping threads) resist loosening thanks to their slight elasticity. They also do not fret or cause galvanic corrosion in joints, which contributes to long-term durability in vehicles that experience constant vibration and exposure to the elements.

Electronics and Electrical Equipment

Perhaps the most extensive use of plastic fasteners is in the electronics industry. From consumer gadgets to industrial electrical panels, these fasteners provide insulation and lightweight strength while securing components. Circuit boards (PCBs) are often mounted using nylon spacers, standoffs, and screws, keeping them in place without risk of a metal fastener shorting out the traces. Power supplies and transformers use plastic nuts and bolts to assemble magnetic cores and attach insulating barriers. The telecommunications industry uses polymer hardware in devices like antennas, radios, and microwave systems because plastic fasteners will not interfere with RF signals or create unintended antenna effects, helping maintain signal integrity and performance.

In high-voltage electrical transmission and distribution, large composite insulator assemblies (for example, the suspension insulators on utility lines) are held together with fiberglass (FRP) rods and fastener components. These provide the required mechanical strength to support cables while maintaining complete electrical isolation from the supporting tower. Even household electrical devices take advantage of plastic hardware – for instance, many electrical outlets and switches use nylon screws to secure cover plates and internal components. These insulating screws protect users from shock by ensuring that even if the screw head is touched, there is no conductive path to the live wiring behind the plate.

Computer and IT equipment make extensive use of polymer fasteners as well. A desktop computer chassis may have plastic stand-offs and guide pins for the motherboard; server racks often employ polymer rail clips and thumb screws to allow tool-less adjustments; and data centers take advantage of non-conductive hardware to avoid grounding loops and to reduce weight in large arrays of equipment. Moreover, plastic fasteners do not interfere with magnetic storage media or sensitive sensors on circuit boards, which is important for ensuring electromagnetic compatibility (EMC) in complex electronic systems.

Medical Devices and Healthcare

The medical field benefits from plastic fasteners in various ways, especially where metal components would pose problems such as imaging interference, patient safety concerns, or aggressive sterilization requirements. In medical imaging equipment like MRI (Magnetic Resonance Imaging) machines, any ferromagnetic components are a serious hazard due to the powerful magnetic fields. Plastic and composite fasteners are used exclusively in and around MRI scanners to ensure that no magnetic materials are present in the assembly. Even in X-ray and CT imaging devices, plastic hardware is preferred in certain locations to avoid artifacts in the images, as polymers are relatively transparent to X-rays compared to metals.

Many surgical instruments and hospital devices employ high-performance polymer fasteners because they can withstand repeated sterilization cycles. Autoclaving (steam sterilization at ~134 °C) pushes many materials to their limits; however, fasteners made from advanced polymers like PPSU (polyphenylsulfone), PEEK, or PEI can endure hundreds of autoclave cycles without losing integrity or dimensional accuracy. This capability is crucial for devices like surgical tool assemblies, endoscopic equipment, and sterilization trays, where components must be sanitized frequently. Using polymer fasteners in these applications also avoids any risk of metal allergies in patients or staff (for example, eliminating nickel-containing screws prevents allergic reactions in sensitive individuals).

In implantable medical devices, PEEK screws have been used as bone screws and suture anchors because PEEK is biocompatible and radiolucent (invisible to X-rays). These properties make it advantageous for long-term implants and imaging follow-ups, as the fastener won’t interfere with X-ray or MRI diagnostics and is well-tolerated by the body. More broadly, in the pharmaceutical and biotech equipment arena, plastic fasteners (often made from PVDF, PTFE, or other FDA/USP Class VI approved polymers) are used in equipment like bioreactors, filtration systems, and drug manufacturing machinery. They ensure that there is no contamination from rust or metal particles, and they withstand aggressive cleaning agents and solvents used in sanitizing such equipment.

Chemical Processing and Offshore Applications

Industries like chemical processing, oil & gas, and marine/offshore engineering push materials to their limits with extremely corrosive and harsh environments, and here composite fasteners truly shine. Chemical plants often replace metal bolts with fluoropolymer or composite bolts in equipment such as pumps, valves, tank flanges, and pipe supports. For example, a PVDF or PTFE bolt can hold together a flange on a chemical reactor where strong acids or chlorine are present, ensuring a long-lasting seal in conditions that would rapidly corrode most other materials. Similarly, composite (FRP) nuts and bolts made with vinyl ester or epoxy resin reinforced with fiberglass are used in structures like chemical storage tanks, scrubber units, and exhaust systems. These fasteners not only resist corrosion but also do not spark, which is a critical safety advantage in flammable or explosive environments (a plastic bolt will not produce a spark the way a steel tool on a steel bolt might).

In marine and offshore structures, the constant exposure to saltwater can rapidly degrade many conventional fasteners. Polymer and composite fasteners offer a solution, as they can endure the saltwater environment with negligible corrosion. Fiberglass-reinforced polyester bolts, for instance, are employed in assembling docks, piers, and ship components specifically to avoid rust and extend maintenance intervals. For example, handrail systems on offshore oil platforms might use composite brackets and bolts so that maintenance is minimized over the platform’s service life, even in salt spray conditions. The lightweight nature of plastic hardware also aids in marine applications – every kilogram saved on a boat or platform can improve buoyancy and stability. Moreover, plastic fasteners are non-conductive, which helps avoid galvanic coupling issues and stray-current corrosion in structures that combine different metals in a saltwater environment. Some naval vessels have even utilized plastic fasteners in sensitive electronic compartments to eliminate magnetic signatures that could interfere with navigation systems or trigger magnetic-based mines.

Other Industrial Applications

There are numerous other areas where composite and plastic fasteners are found. In the semiconductor manufacturing industry, equipment often contains PTFE, PFA, or PVDF fasteners because of the need for ultra-clean, non-contaminating components. These materials do not shed particles or ions that could ruin semiconductor wafers, and they survive the highly corrosive chemicals (like strong acids and solvents) used in chip fabrication processes. In food and beverage processing, plastic hardware (typically using food-grade, FDA-compliant plastics like polypropylene, HDPE, or PVDF) is used in machinery to avoid corrosion and contamination of the product. Plastic fasteners won’t rust or impart metal flakes into food, and they can withstand the frequent washdowns and sanitizing agents used in these facilities.

The construction and infrastructure sector also takes advantage of polymer fasteners in certain cases. Plastic expansion anchors, wall plugs, and insulation fixings are common in building construction – these fasteners resist moisture and provide a thermal break in the building envelope (they do not conduct heat or cold, unlike metal fasteners, which helps improve energy efficiency). In high-voltage infrastructure like power substations and radio transmission towers, large composite bolts and cross-arm members (made of fiberglass composites) provide structural support without creating conductive paths for electricity. This is crucial for maintaining insulation and preventing power losses or arcing.

Across all these industries, the adoption of composite and plastic fasteners is driven by the specific benefits needed in each context – whether it’s a non-sparking, corrosion-proof bolt in a chemical plant, a non-magnetic screw in a medical device, or a lightweight clip in an automobile. This versatility demonstrates how engineered polymers and composites are solving fastening challenges that once required heavier or more complex metal solutions.

Common Plastic Fastener Materials and Key Properties

A wide variety of engineering polymers are used to manufacture fasteners, each with its own balance of strength, durability, thermal tolerance, and chemical resistance. The following table summarizes some of the most common plastic fastener materials and their key properties, to aid in material selection for design:

Material (Polymer)	Typical Tensile Strength (Ultimate, MPa)	Max. Service Temp (Continuous, °C)	Key Properties and Features
Nylon 6/6 (Polyamide)	~75 MPa (unfilled) Up to ~150 MPa with glass fill	~120 °C (dry) ~100 °C (humid)	Tough, resilient thermoplastic; absorbs shock and vibration. Resistant to oils, fuels, and many solvents. Hygroscopic (absorbs moisture), which can impact dimensions and strength over time. Widely used general-purpose plastic fastener due to low cost and a good balance of mechanical properties.
Acetal (POM)	~60–70 MPa (unfilled)	~100 °C	High stiffness and excellent dimensional stability. Low friction surface and very low moisture absorption (good in humid or wet conditions). Strong resistance to creep under load. Commonly used for precision fasteners and small screws that require tight tolerances and smooth threading.
Polyphenylene Sulfide (PPS)	~85 MPa (unfilled) Up to ~140 MPa with glass fill	~200 °C	Excellent chemical resistance to acids, bases, fuels, and solvents. Retains mechanical strength and dimensional stability at elevated temperatures. Inherently flame-retardant (UL94 V-0). Ideal for automotive under-hood parts, electrical/electronic components, and other applications requiring long-term heat endurance and chemical stability.
Polyether Ether Ketone (PEEK)	~90–100 MPa (unfilled) ~150 MPa with 30% GF fill	~250 °C	Ultra high-performance thermoplastic with outstanding heat resistance and mechanical strength. Highly resistant to chemicals (withstands hydrocarbons, solvents, steam) and emits virtually no outgassing. Can endure repeated sterilization cycles. Often used in aerospace, medical, and oil/gas applications; capable of replacing metal in many high-temperature or high-stress scenarios.
Polyvinylidene Fluoride (PVDF)	~40–50 MPa (unfilled)	~150 °C	Specialty fluoropolymer known for exceptional chemical resistance (tolerates strong acids, chlorine, solvents) and excellent UV stability. Maintains toughness in outdoor environments. Lower strength than many engineering plastics, but indispensable in chemical processing equipment, ultra-pure systems, and outdoor applications where harsh chemicals and sunlight are factors.
Polytetrafluoroethylene (PTFE)	~20–30 MPa (unfilled)	~260 °C	Fluoropolymer with the highest chemical inertness – essentially immune to corrosion or solvent attack. Extremely low friction (“self-lubricating”), but relatively low mechanical strength and prone to creep under sustained load. Used for fasteners in highly corrosive or high-purity environments (semiconductor fabrication, laboratory equipment) where no other material will hold up, and where loads are moderate.
Glass-Fiber Composite (GFRP Fasteners)	200–800 MPa with continuous fiber reinforcement	~120 °C (standard resin) ~150 °C (high-temp resin)	Category of fasteners made from thermoset or thermoplastic resin reinforced with continuous fibers (often glass or carbon). Extremely high strength-to-weight ratio and rigidity. Will not corrode and is non-conductive. Often used in place of metal in marine, chemical, or structural applications requiring zero corrosion and low magnetic signature. Fiber directionality must be considered in design (anisotropic properties).

Table: Common polymer materials for fasteners, with representative mechanical strengths and temperature limits. (GF = Glass Fiber. Values are approximate; actual properties depend on specific grades and formulations.)

In addition to the materials above, there are other notable polymers and composites used for fasteners in niche applications. For instance, polycarbonate (PC) is sometimes chosen for transparent or impact-resistant fasteners, polypropylene (PP) for very lightweight and economical fasteners (especially in consumer products and automotive clips), and polyetherimide (PEI) or polysulfone (PSU) for fasteners that need superior flame resistance and the ability to withstand repeated sterilization. Advanced materials like polyamide-imide (PAI) and thermoplastic polyimides see use in extreme aerospace or industrial environments for their exceptional high-temperature capabilities, though their cost often limits widespread use. There are even ceramic fasteners (made of alumina or zirconia) that can serve at ultra-high temperatures or in ultra-clean environments, but they are brittle and typically reserved for only the most demanding specialized situations.

When selecting a material for a plastic fastener, engineers must consider the key properties listed – mechanical strength, maximum service temperature, chemical and UV exposure, electrical requirements, and any industry-specific regulations (such as food-safe or medical-grade certifications, or flammability ratings like UL94). Often a trade-off is involved: for example, a nylon fastener is very economical and tough, but if an application involves high heat or concentrated chemicals, a switch to PPS or PEEK might be required despite the higher cost. The table above provides a starting point for understanding these trade-offs and guiding material choices based on the application’s demands.

Conclusion

Composite and plastic fasteners have firmly established themselves as vital components in modern engineering design, offering a combination of technical performance and practical advantages for challenging applications. By leveraging the intrinsic properties of advanced polymers – from the high tensile strength of fiber-reinforced composites to the remarkable thermal and chemical resistance of PEEK, PPS, and fluoropolymers – engineers can create lighter, more reliable, and more specialized assemblies. These fasteners enable solutions like corrosion-proof connections in chemical plants, non-magnetic fixtures in medical imaging devices, and ultra-lightweight structures in aircraft and spacecraft.

The cost-effectiveness of plastic fasteners, especially in high-volume manufacturing, further accelerates their adoption. They not only reduce material and production costs but also simplify maintenance and improve longevity in harsh conditions, which is economically attractive over a product’s life cycle. As demonstrated across aerospace, automotive, electronics, medical, and other sectors, the use of composite and plastic fasteners aligns with modern engineering priorities of lightweighting, durability, and specialized performance.

In summary, the development of advanced engineering polymers and composite materials has greatly expanded the fastener toolkit available to designers. When chosen and applied thoughtfully, composite and plastic fasteners deliver robust performance – providing high strength, fatigue endurance, thermal stability, and chemical inertness – while also offering unique benefits like electrical insulation, corrosion resistance, and low weight. This makes them indispensable in a growing array of applications. As material science continues to advance, we can expect even more innovative non-metallic fastener solutions that push the boundaries of where polymer and composite hardware can be effectively used in the future.