Do you truly understand the different types of fasteners and when to use them? Do you know what makes each type unique? Can you tell how material choices impact performance? Do you understand which features matter most? Are you clear on how to choose the right one for each application?
Fasteners used in manufacturing are typically divided into three main categories: threaded, non-threaded, and specialty types. Threaded fasteners, such as bolts, screws, and studs, are used where strong, removable connections are needed and are tightened by torque. Non-threaded fasteners include rivets, pins, and dowels, which create fixed or interference-fit joints without threads. Specialty fasteners—like clips, anchors, and retaining rings—are designed for unique applications involving limited space, vibration, or alignment needs. Each type serves a distinct function within manufacturing processes.
Continue reading to learn the classifications, structural features, material types, typical use cases, and selection principles behind all major fasteners used in modern manufacturing.
What is a Fastener?
Fasteners are mechanical components used to join two or more parts together, either temporarily or permanently. They are essential elements in nearly every manufacturing process, from small electronics to large industrial machinery. Without fasteners, the structural integrity of assembled parts would be impossible to maintain. Whether it’s for holding, locking, or aligning, fasteners play a key role in ensuring products remain functional, safe, and serviceable.
The core functions of fasteners include creating firm mechanical connections, allowing disassembly and reassembly, preventing movement under vibration or stress, and supporting structural loads. In both static and dynamic applications, choosing the correct type of fastener can directly affect the reliability and performance of the end product.
To simplify understanding, fasteners are typically categorized into three main types:
- Threaded Fasteners are those with external or internal threads, such as bolts, screws, and studs. They are used for strong, removable connections and are commonly paired with nuts or tapped holes.
- Non-Threaded Fasteners include rivets, pins, and dowel pins. These are used for permanent connections or precise positioning where threads are not required.
- Specialty Fasteners are designed for unique conditions—like limited installation space, high vibration, or non-metallic substrates. Examples include anchors, retaining rings, and thread inserts.
These categories exist because different applications require different fastening methods. A component that needs to be removed for maintenance will likely require a threaded fastener, while a permanent joint in a structural panel may call for a rivet. Specialty fasteners fill the gap where conventional fasteners fall short, offering tailored solutions for demanding environments.
Understanding these main categories is the first step toward mastering fastener selection. It helps you recognize not just what fasteners are, but why specific types are suited to specific tasks. In the sections that follow, we’ll break down each type of fastener in detail—highlighting their features, use cases, and advantages—to help you make informed choices in any manufacturing context.
Threaded Fasteners
Threaded fasteners use helical threads to create secure, removable joints. They convert torque into axial tension, making them ideal for load-bearing assemblies that require disassembly. This group includes bolts, screws, and studs—each suited for specific structural, mechanical, or accessibility needs.
Bolts
Bolts are externally threaded fasteners used with nuts or tapped holes to clamp parts together. They do not cut threads but rely on matched components to maintain tension.
They are classified by head type (hex, socket, flange), thread style (coarse, fine, metric), and strength grade (e.g., 4.8, 8.8, 10.9). Materials include carbon steel for general use, alloy steel for high strength, and stainless steel for corrosion resistance.
Key factors include nut compatibility, torque control, and sufficient thread engagement. Proper preload prevents loosening under vibration or dynamic load.
Bolts are widely used in steel structures, heavy machinery, equipment bases, and anchoring systems.
Screws
Screws are externally threaded fasteners that form or match threads in the material they enter. Most can be installed without a nut.
Common types include machine screws (for tapped holes), self-tapping screws (for sheet metal), and wood screws. Head shapes vary—flat, round, countersunk—and drive types include Phillips, slotted, and hex socket.
Selection depends on material hardness, thread type, and insertion depth. Poor thread engagement or over-tightening can cause failure.
Screws are used in electronics, light frames, control panels, and applications requiring easy disassembly.
Studs
Studs are headless fasteners with threads on both ends or along their full length. They are ideal for joints that must be tightened from one side or require precise alignment.
Types include fully threaded, partially threaded, weld studs, and press-fit studs. They offer better clamping consistency and can be reused without damaging the threads in the base part.
Technical considerations include axial alignment, preload control, and use of thread locking where needed.
Studs are common in flanged joints, valve assemblies, engine housings, and surface-mounted components.
Non-Threaded Fasteners
Non-threaded fasteners are used to create fixed joints or precise alignment without threads. They are often permanent and rely on mechanical deformation, interference fit, or insertion force. These fasteners are ideal for applications where disassembly is rare or not required, such as structural frames, housings, and machine components.
Rivets
Rivets are permanent fasteners used to join materials by deforming one or both ends after insertion. Once set, they create strong shear-resistant joints without relying on threads.
Common types include solid rivets, hollow rivets, blind (pop) rivets, and explosive rivets. Solid rivets require access from both sides and are installed by hammering or pressing. Blind rivets can be installed from one side using a rivet gun, making them useful in closed assemblies. Explosive rivets are self-driving and used in aerospace for precision fastening.
Rivets are widely used in sheet metal, structural frames, aircraft skins, and enclosures where welding isn’t practical or vibration resistance is essential.
Pins
Pins are cylindrical or tapered fasteners inserted into aligned holes to locate, retain, or limit movement between parts. Unlike bolts, they do not rely on threading and typically resist shear forces.
Types include straight pins, taper pins, spring pins (also known as slotted or roll pins), and cotter pins. Spring pins offer flexibility and preload, while cotter pins are used with clevis joints to prevent unintentional disengagement.
Pins serve as alignment aids, rotation stops, or locking devices. They are commonly found in couplings, gear assemblies, bearing housings, and linkage joints to prevent displacement and maintain structure.
Dowel Pins
Dowel pins are solid, precision-ground cylindrical pins used for exact positioning between mating parts. They fit tightly into holes with specified tolerances, usually following H7/h6 fit standards.
These fasteners ensure precise alignment during assembly and are often used in jigs, fixtures, molds, and die-cast components. Installation methods include press-fitting or thermal expansion techniques for high-stability results.
Dowel pins are critical in applications requiring repeatable accuracy, such as guide rails, housing alignment, or multi-part component integration.
Specialty Fasteners
Specialty fasteners are designed for unique installation challenges, such as limited access, non-standard materials, or extreme operating conditions. They solve problems that conventional fasteners cannot handle, offering custom fit, improved load control, or added functionality in tight or high-stress environments.
Anchors
Anchors are fasteners used to attach components to concrete, masonry, or other solid bases. They work by expanding inside a drilled hole or bonding chemically to the substrate to resist pull-out and shear forces.
Main types include expansion anchors and chemical anchors. Expansion anchors, such as wedge or sleeve anchors, expand against the walls of a drilled hole when tightened. Chemical anchors use resin-based adhesives to secure threaded rods or bolts inside the hole, allowing for stronger bonds in cracked or porous materials.
Anchors are used in foundations, brackets, supports, and overhead installations where bolts can’t be embedded directly.
Retaining Rings and Clips
Retaining rings and clips are circular fasteners used to hold components onto a shaft or inside a bore. They resist axial movement and prevent parts from sliding off during rotation or load changes.
Types include internal rings, external rings, and wave washers. Internal rings fit into bores, external rings snap onto shafts, and wave washers apply spring force to absorb shock or reduce endplay.
These fasteners are used in rotary shafts, piston assemblies, gear sets, and bearings. Their compact design and ease of installation make them ideal for high-speed or space-limited mechanisms requiring axial retention.
Thread Inserts
Thread inserts are metal sleeves or coils installed into base materials to create or restore strong internal threads. They are commonly used in softer materials where standard threading would strip under stress.
Available in stainless steel, brass, or locking types, inserts can either be helically coiled or solid-bodied. Locking variants provide added resistance to vibration and thread loosening.
Inserts are used in aluminum or plastic parts to reinforce screw holes, extend thread life, or repair damaged threads. Typical applications include electronics housings, castings, instrument panels, and any scenario requiring reliable thread strength in lightweight materials.
Fastener Materials and Mechanical Properties
The material of a fastener directly affects its strength, corrosion resistance, cost, and suitability for specific environments. Choosing the right material ensures reliable performance under load, vibration, temperature change, or chemical exposure. Both metallic and non-metallic fasteners serve critical roles depending on the application.
Common Metal Fasteners
Most fasteners are made from carbon steel, alloy steel, or stainless steel. Each has distinct mechanical properties and cost implications.
Carbon steel is the most widely used due to its affordability and moderate strength. It is suitable for general-purpose fasteners but requires protective coatings to resist corrosion. Alloy steel contains additional elements like chromium and molybdenum, offering higher tensile strength and better performance under stress. Stainless steel resists rust and chemical attack, making it ideal for outdoor or corrosive environments, though it has lower tensile strength than alloy steel.
Strength grades, such as 8.8 or 12.9, indicate a fastener’s tensile and yield limits. These ratings follow international standards and help match fasteners to expected loads and stress conditions.
Material choice impacts heat treatment compatibility, magnetic properties, and fatigue resistance. For structural or safety-critical joints, selecting the correct metal fastener is essential.
Non-Metallic Fasteners
Non-metallic fasteners include those made from nylon, plastic, or composite materials. These fasteners are non-conductive, lightweight, and corrosion-resistant, but they have lower mechanical strength compared to metals.
Nylon fasteners are common in electronics and electrical assemblies where insulation and EMI shielding are important. They also offer vibration damping and chemical resistance. Plastic fasteners are easy to mold into complex shapes and are often used in consumer products and automotive interiors. Fiber-reinforced composites offer improved strength while retaining weight and corrosion benefits.
These materials are suitable for low-load or non-structural applications, especially where metal would be too heavy, reactive, or conductive. Selection depends on exposure to heat, UV, chemicals, or mechanical stress.
Surface Treatments & Coatings
Surface treatments and coatings improve a fastener’s resistance to corrosion, wear, and environmental damage. They also enhance appearance, extend service life, and support specific installation needs. Choosing the right finish depends on where and how the fastener will be used.
Common Coatings
Zinc plating is a widely used finish that provides moderate corrosion protection at a low cost. It creates a thin, silvery layer over carbon steel and is suitable for indoor or dry environments. However, it has limited performance in high-humidity or salt-rich conditions.
Black oxide is a chemical conversion coating that offers minimal corrosion resistance but improves lubricity and appearance. It is used where aesthetics matter or where fasteners must resist galling during installation. Black oxide is common in tools, electronics, and low-moisture mechanical assemblies.
Hot dip galvanizing applies a thick zinc layer by immersing the fastener in molten zinc. It delivers excellent protection in outdoor, marine, or industrial environments. The coating is durable but adds bulk, which can affect fit and thread engagement in tight assemblies.
Each method offers a trade-off between cost, protection level, and application complexity.
Choosing Surface Treatments
Selecting the right surface treatment depends on environmental exposure, mechanical stress, and assembly requirements.
For indoor or dry-use fasteners, zinc plating is often sufficient. In high-moisture or outdoor settings, hot dip galvanizing is preferred due to its long-lasting protection. Black oxide suits internal components where appearance and wear resistance matter more than corrosion protection.
In corrosive or chemically active environments—such as coastal areas, chemical plants, or food processing lines—consider stainless steel fasteners or specialty coatings like Teflon or epoxy.
Other factors include required torque, need for reusability, temperature extremes, and whether dissimilar metals are in contact (to avoid galvanic corrosion). Matching the coating to the working conditions ensures the fastener maintains its function and lifespan.
Fastener Selection Principles
Choosing the right fastener is critical to ensuring structural safety, long-term durability, and maintenance efficiency. Selection depends on multiple factors including mechanical loads, environmental conditions, installation methods, and potential for future disassembly. A mismatch between fastener type and application can lead to loosening, fracture, or premature failure.
Load, Stress & Application Factors
Fasteners must be selected based on the types of forces they will encounter—tensile, shear, and combined loads. Tensile loads try to pull the joint apart, while shear forces act across the fastener body. Each type requires specific structural features.
For example, bolts with a larger shank diameter resist shear better, while high-strength grades like 10.9 or 12.9 handle heavy tensile loads. In dynamic applications with vibration, use locking mechanisms like washers, thread lockers, or prevailing torque nuts to prevent loosening.
Engineers also consider joint stiffness, material compatibility, and preload requirements. If the fastener is the weakest link in the load path, it will fail first. Therefore, matching fastener capacity to load expectations is fundamental in any design.
Installation, Maintenance & Disassembly
Ease of installation and future service access also influence fastener selection. Threaded fasteners are ideal for assemblies that require repeated removal or inspection. In contrast, rivets or adhesives are suited for permanent joints with no maintenance requirement.
Fasteners must be accessible with standard tools and allow proper torque application. If assembly space is limited, use socket-head screws or captive fasteners. For large assemblies, consider installation speed—self-tapping screws or pre-attached washers can reduce time and errors.
The durability of a fastener depends not only on its material, but also on how it’s assembled. Under- or over-tightening can weaken threads, stretch the fastener, or damage the mating surface. Following manufacturer torque guidelines ensures consistent performance over time.
Common Mistakes to Avoid
Beginner mistakes often stem from underestimating mechanical or dimensional requirements. Using a fastener that is too short may result in poor engagement and pullout. Using one that is too long can bottom out in blind holes or interfere with internal components.
Choosing the wrong strength grade—such as a low-grade bolt for a high-load structure—can lead to shearing or fatigue failure. Misunderstanding material compatibility can also cause galvanic corrosion between dissimilar metals.
To avoid these issues:
- Always verify load type and expected forces.
- Use washers to distribute pressure and prevent surface damage.
- Check thread engagement length—typically, at least 1 to 1.5 times the bolt diameter.
- Match strength grade to application needs, not just availability.
Proper fastener selection requires attention to both mechanical and practical constraints. A reliable connection starts with informed choices, not assumptions.
Fastener Standards and Strength Grades
Global engineering depends on unified standards. Fastener standards define dimensions, material properties, testing methods, and performance classifications. Understanding these systems ensures compatibility across regions, industries, and suppliers.
ISO, DIN, ANSI, GB Standards
Four main systems dominate international fastener specifications: ISO (International Organization for Standardization), DIN (German Institute for Standardization), ANSI (American National Standards Institute), and GB (Guobiao Standards of China).
ISO standards are globally accepted and widely used in cross-border manufacturing. DIN, originally a German system, aligns closely with ISO but sometimes retains legacy codes in European markets. ANSI standards are prevalent in the United States, particularly in automotive, aerospace, and construction industries. GB standards are mandatory in China and often harmonized with ISO or DIN for international export.
Fasteners are labeled with standard codes to specify size, thread pitch, strength grade, and surface finish. For example, ISO 4014 refers to a hex head bolt, while DIN 933 denotes a similar metric screw. Understanding these labels helps ensure parts sourced from different regions meet equivalent quality and fit requirements.
Mechanical Grades Explained
Fastener strength is categorized by mechanical grades that define yield strength and tensile strength. These grades help engineers match fastener capacity to structural loads.
Metric fasteners often use two-digit numbers like 4.8, 8.8, 10.9, and 12.9. The first number indicates one-tenth of the nominal tensile strength in MPa (e.g., 8 = 800 MPa), and the second number represents the ratio of yield to tensile strength. So an 8.8 bolt has 800 MPa tensile strength and 640 MPa yield strength (800 × 0.8).
Grade 4.8 bolts are low-strength and suited for light-duty applications. Grade 8.8 bolts offer higher strength and are widely used in structural steel and machinery. Grades 10.9 and 12.9 are high-strength fasteners for critical load-bearing joints, especially in automotive, pressure vessels, and high-impact environments.
Choosing the correct grade ensures safety, prevents over-engineering, and keeps costs under control.
Fasteners in Key Industries
Different industries face unique technical demands that directly influence fastener selection. Whether it’s resisting vibration, ensuring sterility, or withstanding extreme temperatures, the application determines which type of fastener is most suitable.
General Industrial Use
In general manufacturing, fasteners are used across machinery, automation frames, and piping systems. Most applications prioritize durability, ease of assembly, and cost efficiency.
Bolts and screws with standard zinc coatings are common in equipment housings and support frames. Self-tapping screws simplify installation in light-gauge sheet metal or enclosures. Pipe clamps and brackets often use anchor bolts or threaded studs for secure, vibration-resistant mounting.
Maintenance is a key factor. Removable fasteners with standard drive heads and reusable threads allow quick service and replacement. Lock washers or thread lockers help prevent loosening from repeated operation or mechanical stress.
The focus in this segment is performance consistency, low maintenance cost, and flexibility for component replacement.
Automotive, Aerospace, Medical
In the automotive industry, fasteners must endure high temperatures, vibration, and dynamic loads. Bolts with locking features, such as serrated flanges or thread patches, prevent loosening under shock. High-strength grades like 10.9 or 12.9 are used in engine mounts, suspension components, and chassis assemblies.
Aerospace fasteners prioritize weight reduction, fatigue resistance, and certification standards. Titanium and aluminum alloy fasteners are common for their strength-to-weight ratio. Rivets and flush screws are used in skin assemblies where smooth airflow is critical. Fasteners must meet strict standards for tensile strength, reliability, and corrosion resistance in varying altitudes and temperatures.
Medical equipment demands non-corrosive, sterile-compatible fasteners. Stainless steel or coated titanium screws are used in diagnostic machines, surgical tools, and implant fixtures. These fasteners must allow easy disassembly for cleaning, avoid particle generation, and maintain thread integrity after multiple sterilization cycles.
Each sector reflects how functional demands shape the types of fasteners selected. The right choice balances performance, reliability, and compliance with industry-specific standards.
Conclusion: Types of Fasteners
Mastering fasteners begins with understanding their core classifications—threaded, non-threaded, and specialty types—each suited to specific mechanical needs. From there, material selection, surface coatings, and mechanical grades define their performance under stress, vibration, and corrosion. We also explored practical guidelines for fastener selection and examined how industries—from automotive to aerospace—match fastener types to unique operating conditions. Together, these insights form a structured framework for making reliable fastening decisions in real-world manufacturing.
In industries like CNC machine tool production, where every micron matters and every assembly must endure vibration, torque, and thermal cycles, fastener strategy is part of the design philosophy. At Rosnok, we apply these principles in the development of our precision machining centers, integrating the most suitable fastening technologies into high-load frames, dynamic axes, and modular enclosures—ensuring that our machines remain not only accurate, but also structurally resilient across global applications.
