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Author: Site Editor Publish Time: 2025-06-13 Origin: Site
Bolt fasteners are tools used to hold parts together. They are important for keeping buildings, bridges, and structures strong. Without good bolt fasteners, structures can become unsafe or fall apart.
Knowing the types of bolt fasteners helps in construction choices. By 2033, the market for these tools may reach $70.8 billion. This growth is due to more cities and big projects. Bolts and fasteners keep things safe and lasting, making them very important today.
Knowing bolt parts helps you pick the right one. Each part has a job to make bolts strong and long-lasting. Let’s look at the main parts.
The bolt head is the top part of a bolt. It handles pressure and comes in different shapes. Common shapes include hex, countersunk, and dome heads. Hex heads are popular because they work well with wrenches. Countersunk heads sit flat on surfaces for a smooth look. Dome heads are round and often used for decoration. You can find pictures of these head types in online guides.
The shaft is the bolt’s main body, linking the head to the threads. It has two sections: the smooth shank and the ridged thread. Threads let nuts grip tightly, holding parts together. Guides like the ANSI Hardware Design Guide explain bolt shaft details. These guides help engineers calculate how much weight bolts can handle. This ensures bolts are strong enough for their jobs.
Nuts and washers make bolts work better. Nuts screw onto bolts to hold things tight. Washers are flat rings placed under the bolt head or nut. They spread out pressure and reduce shaking. Some washers, like lock washers, stop bolts from loosening. Others, like insulating washers, are used in electronics to block electricity. Together, these parts make bolts stable and reliable for many uses.
Knowing bolt types helps you pick the right one. Each type has special uses and strengths. It's important to understand their limits too.
Hex bolts are very common in building and machines. Their six-sided heads fit wrenches well, giving strong grip. They are used for heavy tasks like holding big machines or parts.
Hex bolts are flexible and come in many sizes and materials. Stainless steel and strong alloys are popular choices. They work indoors and outdoors. Studies show high-strength steel hex bolts, like grades 8.8 and 12.9, handle stress well. These bolts are great for tough jobs with lots of pressure.
Feature | Hex Head | Industry Average |
|---|---|---|
Torque Capacity | 120 Nm | 95 Nm |
Vibration Resistance | 2,200 hrs | 1,800 hrs |
Corrosion Resistance | 1,000 hrs salt spray | 750 hrs |
This table shows hex bolts are better than average. They resist rust, shaking, and handle strong force. Hex bolts are a solid choice for hard tasks.
Carriage bolts have round heads and flat bottoms. They are used for wood-to-wood or wood-to-metal connections. Their smooth heads stop people from turning them after installation.
Carriage bolts are common in furniture, fences, and decks. Their square neck locks into wood, keeping them steady while tightening. This makes them secure and reliable.
Carriage bolts are weaker than hex bolts, with torque around 85 Nm. But they look nice and are hard to tamper with. They resist rust for about 600 hours in tests, making them good for outdoor use. However, they don’t last as long as hex bolts in tough weather.
Anchor bolts attach structures to concrete or brick. They are key for safety in big projects like steel columns or heavy machines.
Anchor bolts come in shapes like L, J, or straight rods. Each shape has a purpose. L-shaped bolts are for buildings, while straight ones hold heavy machines.
Strong steel anchor bolts, like grades 8.8 or 12.9, handle heavy loads well. But experts say more research is needed for earthquake areas.
Anchor bolts are stronger than hex and carriage bolts. They carry heavy loads and are made for big construction jobs.
Flange bolts are special because they have a washer built-in. This washer, under the hex head, spreads pressure evenly. It helps protect surfaces from damage. These bolts are often used in cars and plumbing. They hold parts like engines, pipes, and frames securely.
A big benefit of flange bolts is their grip. The wide flange keeps them tight, even with vibrations. For example, car engines use them because of constant movement.
Tip: Always check the material of flange bolts. Stainless steel resists rust well. Carbon steel is stronger for heavy tasks.
Feature | Flange Bolts | Standard Bolts |
|---|---|---|
Load Distribution | Excellent | Moderate |
Vibration Resistance | High | Low |
Corrosion Resistance | 800 hrs salt spray | 500 hrs |
This table shows why flange bolts are better than standard ones. They last longer and stay secure, making them great for tough jobs.
U-bolts are named for their U-shape. They are great for holding pipes, tubes, or round items to flat surfaces. You’ll see them in construction, cars, and boats. They secure things like exhausts, poles, or trailers.
U-bolts are very flexible. They come in many sizes and materials. Galvanized U-bolts resist rust, so they work well outdoors.
Note: Measure the pipe or object before picking a U-bolt. A good fit keeps things stable and prevents damage.
U-bolts are strong and handle heavy loads well. Their curved shape spreads pressure evenly. This makes them reliable for holding heavy or stressed parts.
Shoulder bolts, or stripper bolts, have a smooth middle section. This part, called the shoulder, is between the head and threads. They are used as pivots, axles, or guides in machines. You’ll find them in cars, furniture, and machinery.
The shoulder gives a precise fit, perfect for moving parts. They are often used in pulleys, gears, and sliding systems.
Did You Know? Shoulder bolts are made from strong materials like alloy or stainless steel. This helps them last in tough conditions.
When choosing shoulder bolts, check the shoulder length and diameter. These sizes affect how well they work. Picking the right size ensures smooth movement and less strain on parts.
Eye bolts are special fasteners with a loop, or "eye," on one end. This loop lets you attach ropes, chains, or cables securely. They are often used for lifting, rigging, and holding heavy loads. You can find them in construction, shipping, and outdoor activities like ziplining.
There are two main types of eye bolts: shoulder eye bolts and non-shoulder eye bolts. Shoulder eye bolts have a ridge, called a shoulder, near the loop. This makes them good for angled or side pulls. Non-shoulder eye bolts work better for straight, vertical pulls.
Tip: Always check how much weight an eye bolt can hold. Using too much weight can bend or break it, causing accidents.
When picking eye bolts, think about the material. Stainless steel doesn’t rust and is great for outdoor use. Carbon steel is stronger and better for heavy tasks. Make sure to install the bolt fully into the material. This helps it hold securely.
Lag bolts, also called lag screws, are strong fasteners made for wood. They have a hex head and thick threads that grip wood tightly. These bolts are used for building decks, securing beams, or attaching heavy items to walls.
Unlike regular screws, lag bolts need pre-drilled holes. This stops the wood from cracking and ensures a tight fit. Once installed, they hold very well, making them perfect for strong structures.
Lag bolts come in different sizes and lengths. For outdoor projects, use galvanized or stainless steel lag bolts. These resist rust and last longer. Always use a wrench or socket to tighten them properly.
Did You Know? Lag bolts are great for DIY projects like hanging shelves or mounting TVs. They are strong and reliable, making them a popular choice for homeowners.
Machine bolts are useful fasteners for connecting metal or wood. They have a flat or hex head and threads along the shaft. Nuts and washers are often used with them to make a secure connection.
You’ll see machine bolts in construction, cars, and factories. They are used to build machines, fix equipment, or assemble structures. These bolts come in different materials like stainless steel, carbon steel, and brass.
When choosing machine bolts, check the thread type. Coarse threads are easier to use and work well in soft materials. Fine threads grip tighter and are better for high-stress jobs. Always use the right tools, like a wrench, to tighten them.
Note: Machine bolts don’t cut their own threads. You’ll need to drill holes and use matching nuts for a secure fit.
Rock bolts are important tools for underground work like mining and tunnels. They keep rocks steady by attaching loose ones to solid structures. You’ll see them where safety and strength are very important.
There are different types of rock bolts for various needs:
Mechanical Rock Bolts: These expand inside rocks to hold firmly.
Resin Rock Bolts: These use glue-like resin to stick to rocks.
Friction Rock Bolts: These stay in place using friction.
Tip: Pick the right rock bolt based on the rock type and weight it must hold. This keeps things safe and works best.
Rock bolts are made of strong steel to carry heavy loads and avoid rust. They stop rocks from falling and keep underground areas stable. Installing them correctly is very important, so follow the maker’s instructions.
Elevator bolts have flat heads and are used in elevators and conveyors. Their wide, flat tops stop damage to belts or materials. They are great for jobs needing smooth surfaces.
Main features of elevator bolts include:
Flat, Countersunk Head: This design avoids blocking moving parts.
Long, Threaded Shaft: It helps secure materials tightly.
Corrosion Resistance: Options like stainless steel last longer.
You’ll find these bolts in farming, factories, and food work. They hold conveyor belts, grain elevators, and machines. When choosing elevator bolts, check the size and material for a good fit.
Did You Know? Elevator bolts are also handy for DIY tasks like fixing furniture. Their flat heads make them useful for many projects.
Blind bolts are special fasteners for places you can’t reach both sides. They are great for tight spaces and hard-to-access areas. These bolts are used in building, planes, and cars.
Blind bolts have three main parts:
Bolt Body: The strong middle part.
Collar: This spreads out to hold the bolt tight.
Pin: It locks the bolt after it’s in place.
Blind bolts are simple to use and need few tools. They work well for steel frames, bridges, and plane parts. They are strong and trusted by builders and engineers.
Note: Always check how much weight blind bolts can hold. Using too much weight can make them fail.
J-bolts look like the letter "J" and are strong fasteners. Their curved shape helps secure items to concrete or solid surfaces. They are often used in construction for walls, poles, or machines. The hook-like end grips tightly, keeping things safe and steady.
These bolts come in different sizes and materials. Galvanized steel J-bolts don’t rust, so they’re great for outdoor use. Stainless steel ones work well in wet or chemical-filled areas. Always check the weight the bolt needs to hold. Picking the right size stops accidents and keeps things durable.
Tip: Drill holes in concrete before using J-bolts. This improves grip and keeps structures stable.
J-bolts are simple to use and work in many projects. You can use them for fences or heavy equipment. Follow the maker’s instructions to install them correctly for the best results.
Plow bolts are tough fasteners made for hard jobs. They have flat heads that sit even with surfaces, avoiding problems with moving parts. These bolts are used in farming tools, snowplows, and big machines.
The flat head reduces wear on surfaces, making them last longer. This feature is great for jobs needing smooth operation. Industries needing strong fasteners for heavy tasks often use plow bolts.
Plow bolts are made from strong materials like carbon or alloy steel. These materials help them carry heavy loads and resist damage. For outdoor use, pick bolts with coatings that stop rust. This makes them last in bad weather.
Did You Know? Plow bolts were first made for plows but are now used in many industries because of their strength.
Make sure the flat head fits tightly into the surface when installing. This stops movement and keeps the connection secure. Proper installation helps the bolt and equipment last longer.
Sex bolts, also called barrel nuts, are two-part fasteners. They include a bolt and a nut that fits inside a hollow barrel. This design looks neat and is popular for furniture, signs, and building projects.
These bolts are easy to use and hold things firmly. The barrel nut adds extra strength, keeping the bolt steady. Sex bolts are often used where appearance matters, like in display cases or panels.
Sex bolts come in materials like aluminum, brass, or stainless steel. Each material has benefits. Stainless steel doesn’t rust, while brass looks decorative. Pick the material that fits your project best.
Note: Measure the thickness of the items you’re joining. This ensures the bolt and nut fit well for a secure finish.
Sex bolts are reusable and versatile. Their simple design makes them great for DIY and professional projects. Whether building furniture or making signs, these bolts are reliable and look good.
Socket head bolts are strong fasteners with a round head. They have a hex-shaped hole for tightening with an Allen wrench. These bolts are used in cars, planes, and machines because they save space and hold tightly.
Compact Design: Their small heads fit into tight spaces easily. This makes them great for places where big bolts won’t work.
High Strength: Made from tough materials like stainless or alloy steel, they handle heavy loads and last long.
Ease of Use: The hex socket stops slipping, making tightening secure and simple.
Tip: Always match the Allen wrench size to the bolt. Using the wrong size can damage the bolt’s head.
Socket head bolts come in different styles like button, flat, and cap heads. Button heads look nice and are decorative. Flat heads sit even with surfaces for a smooth finish. Cap heads are the strongest and work well under high pressure.
T-head bolts have a flat, T-shaped top. This shape lets them slide into grooves or slots. They are great for adjustable connections in construction, railways, and big machines.
Adjustability: The T-head fits into tracks, making it easy to move and position.
Secure Fit: Once tightened, the bolt stays in place and doesn’t move.
Durability: Made from strong materials like carbon or stainless steel, they resist rust and wear.
Note: Make sure the slot matches the T-head size. A good fit stops slipping and keeps the bolt steady.
These bolts are perfect for jobs needing strength and flexibility. They are often used in clamps, fixtures, and assembly lines. Their design makes them easy to install and adjust, saving time.
Square bolts have a square-shaped head and are old-style fasteners. They were common before hex bolts became popular. Today, they are used for their vintage look and strong grip. You’ll see them in woodworking, repairs, and heavy-duty tasks.
Better Grip: The square head gives more surface for tools, reducing slipping.
Rust Resistance: Many are galvanized or made of stainless steel, so they work well outdoors.
Classic Look: Their old-fashioned design adds style to restoration projects.
Did You Know? Square bolts are great for woodwork because their shape stops them from turning in wooden joints.
When picking square bolts, check the material and size. Galvanized ones are good for wet areas, while carbon steel ones handle heavy loads. Installing them properly ensures they stay secure and last long.
Knowing bolt grades helps you pick the right one. In the U.S., bolts are grouped by material and strength. The most common grades are Grade 2, Grade 5, and Grade 8.
Grade 2 bolts are made of soft steel. They are used for simple tasks. These bolts have no markings, so they’re easy to spot.
Grade 5 bolts are stronger and made of medium-carbon steel. They are used in cars and buildings. Look for three lines on their heads.
Grade 8 bolts are the toughest. They are made of alloy steel and used for heavy-duty jobs. Six lines on the head show their grade.
Bolt Grade | Material | Proof Load (psi) | Minimum Yield Strength (psi) | Minimum Tensile Strength (psi) | Identification | Applications |
|---|---|---|---|---|---|---|
Grade 2 | Low carbon steel | N/A | N/A | N/A | No markings | General applications |
Grade 5 | Medium carbon steel | 74,000–85,000 | 81,000–92,000 | 105,000–120,000 | Three radial lines | Automotive, construction |
Grade 8 | Alloy steel | N/A | N/A | N/A | Six radial lines | High-strength applications |
Metric bolts use numbers like 8.8, 10.9, and 12.9 to show strength. These grades are common worldwide and match certain U.S. grades.
Grade 8.8 bolts are made of treated medium-carbon steel. They are like U.S. Grade 8 bolts and used in building structures.
Grade 10.9 bolts are stronger and made of alloy steel. They work well in high-stress jobs.
Grade 12.9 bolts are the strongest. They are made of alloy steel and used in heavy machines.
Metric Bolt Grade | Equivalent US Bolt Material | ASTM Grades |
|---|---|---|
8.8 | 8 | A325, A449 |
10.9 | 10 or 12 | A490, A354, 8D |
12.9 | 10 or 12 | A540; B21–B24 |
You can tell bolt grades by their head markings. U.S. bolts have lines, while metric bolts have numbers like 8.8 or 10.9. These marks show how strong the bolt is. Always choose the right grade for your project to keep it safe and strong.
Bolt grades are important for keeping projects safe and strong. Each grade has its own strength and is made for specific jobs. Knowing these grades helps you pick the right bolt.
Grade 2 bolts are good for light tasks. Use them for fixing furniture, small repairs, or simple jobs. They are not strong enough for heavy loads but work fine for easy connections.
Grade 5 bolts are stronger and more useful. They are often used in cars, buildings, and farm tools. For example, they are great for car engines because they handle stress and shaking well.
Grade 8 bolts are the toughest of the common bolts. They are made for hard jobs like big machines, factory tools, and steel structures. When you need the strongest bolts, choose Grade 8.
Metric bolts, such as 8.8, 10.9, and 12.9, are used worldwide. For example, 8.8 bolts are good for medium-strength jobs, while 12.9 bolts are best for heavy machines.
Tip: Always check the grade markings on bolts before using them. Picking the wrong grade can cause problems and make things unsafe.
Choosing the right bolt grade keeps your project safe, strong, and long-lasting.
Knowing thread types helps you pick the right bolt. Threads decide how bolts hold things together. Here are three common thread types.
Metric threads are used worldwide because they are precise and standard. They are measured in millimeters, making them simple to use. The thread angle is always 60 degrees, so they fit well in many jobs. Engineers and builders trust metric threads for their reliability.
These threads follow ISO rules, ensuring a good fit and high quality. They have a finer pitch, which means more threads per length. This makes them great for tasks needing accuracy, like building machines or electronics.
Feature | Metric Threads | Inch Threads |
|---|---|---|
Measurement Units | Millimeters between threads | Inches between threads |
Thread Angle | Standardized at 60 degrees | Varies, commonly 60 or 55 degrees |
Tolerance & Fit | Adheres to ISO standards | Follows Unified Thread Standard |
Strength & Precision | Finer pitch for higher precision | Variable pitch for flexibility |
Metric threads are precise and work well globally. They are perfect for projects needing exact measurements.
UNC threads are common in the U.S. They have wider spacing between threads, making them easy to use. These threads are great for woodwork, construction, and repairs.
The coarse threads grip soft materials like wood or plastic better. They also save time during assembly. However, they are less precise than metric threads. For simple and strong connections, UNC threads are a good choice.
UNF threads have closer threads than UNC threads. This gives a tighter and stronger fit. They are often used in cars, planes, and other high-stress jobs.
The fine pitch makes these bolts stronger and less likely to loosen. They are ideal for tasks needing durability and precision. UNF threads are a top pick for tough and exact jobs.
Tip: Thread Check, Inc. says metric and unified threads have matching gage standards. For example, a metric 6g ring can replace a Unified 2A ring. Always match the thread type to your project for the best results.
By learning about thread types, you can choose the best bolt. Each type has its own strengths, ensuring a secure connection.
British Standard (BS) threads were created in the United Kingdom. They follow set rules to ensure they work well in different jobs. These threads are common in construction, engineering, and manufacturing.
Thread Angle: BS threads have a 55-degree angle. This is different from the 60-degree angle in metric and unified threads.
Types of BS Threads: There are two main types:
BSW Threads: These have thick threads for general use.
BSF Threads: These have thin threads for precise tasks.
Measurement Units: BS threads are measured in inches, not millimeters like metric threads.
BS threads have many benefits:
Durability: The 55-degree angle makes them strong and less likely to strip.
Versatility: They work for both heavy-duty and detailed tasks.
Compatibility: They are often used in old machines, making them great for repairs.
Tip: Always check the thread type before replacing old bolts or screws. Using the wrong one can cause damage or make the connection fail.
BS threads are used in jobs needing strong and dependable fasteners, such as:
Construction: Holding beams and structures together.
Engineering: Building machines and tools.
Restoration: Fixing old equipment or vehicles.
Learning about BS threads helps you pick the right fastener. Their special design makes them strong and reliable for tough jobs.
Picking the right bolt fastener keeps your project safe and strong. Each type has special features for different jobs. By knowing key factors, matching bolt grades, and checking thread fit, you can choose wisely.
When selecting a bolt fastener, consider important factors for your project. These include material, strength, and the environment.
Material: Match the fastener material to the connected parts. For example, stainless steel resists rust in wet areas. Carbon steel is strong and good for heavy-duty tasks.
Strength: The fastener must hold the weight it will carry. Weak fasteners can break, causing damage or accidents. Always check the bolt’s load limit.
Environment: The surroundings affect fastener choice. Heat-resistant bolts work in hot places. Outdoor projects need bolts that resist rust.
The table below shows these factors:
Factor | Description |
|---|---|
Usage needs | Bolts must fit the job’s environment and weight limits. For example, hot areas need heat-resistant bolts. |
Material match | Bolt material should suit the connected parts. Stainless steel resists rust in wet areas. Carbon steel is strong for heavy tasks. |
Size accuracy | Bolt size must fit the connector for a secure hold. Wrong sizes can cause problems. |
Strength check | Bolts must handle the weight to avoid breaking. Weak bolts can lead to accidents. |
Tip: Measure the bolt and connector size before use. A good fit avoids problems and lasts longer.
Bolt grades show how strong and durable a fastener is. Picking the right grade for your job keeps things safe and efficient. Standards like ASTM help you choose the correct grade.
The table below lists common grades and uses:
Standard | Description |
|---|---|
ASTM A193 | Alloy and stainless steel bolts for high heat or pressure. |
ASTM A320 | Alloy steel bolts for cold environments. |
ASTM A194 | Nuts made of carbon, alloy, or stainless steel for high heat or pressure. |
B7 Studs | Used in vessels under 750°F, with finishes to resist rust. |
B16 Studs | Made for high heat jobs between 751-1100°F. |
2H Nuts | Stronger than B7 studs, breaking the stud before the nut. |
B7M Studs | Lower strength studs for hydrogen stress corrosion jobs. |
2HM Nuts | Best for stress corrosion environments. |
For example, ASTM A193 bolts work well in high-pressure jobs. ASTM A320 bolts are better for cold places. Always check the maker’s guide to pick the right grade.
Note: Using the wrong grade can cause safety problems. Check the bolt head markings before installing.
Thread fit is key for a strong connection. If threads don’t match, bolts can loosen or fail. Always make sure the bolt and nut threads align properly.
There are different thread types, like metric, UNC, and UNF. Each type has its own use. For example:
Metric threads are accurate and common in machines.
UNC threads work well with wood and soft materials.
UNF threads are tight-fitting and good for cars and planes.
Tip: Check thread type and pitch before pairing bolts and nuts. This ensures a strong hold.
Thread fit also depends on the nut type. Lock nuts stop loosening in shaky areas. Wing nuts are easy to tighten by hand. Picking the right bolt and nut combo improves fastener performance.
Manufacturers are key to making sure bolt fasteners are safe and strong. Their work affects the safety of buildings, bridges, and machines. By following strict rules, they ensure bolts meet high standards.
Manufacturers use advanced tools and tests to check quality. They carefully pick suppliers who meet strict rules. Samples are tested, and production methods are reviewed for consistency. During production, they check bolts through tests and inspections. These steps make sure bolts meet all needed requirements before being sold.
Did You Know? Many manufacturers follow ISO 9001 rules. This certification shows they focus on making high-quality products efficiently.
Testing is very important for quality. Manufacturers use special labs certified by ISO/IEC 17025. These labs test bolts for strength, hardness, and thread fit. They also check if bolts meet environmental rules like RoHS. These tests ensure bolts are safe and reliable.
Good quality bolts prevent accidents. Imagine a bolt breaking in a bridge or machine—it could be dangerous. Choosing bolts from trusted manufacturers lowers this risk. It ensures bolts last long and work well. Manufacturers’ focus on quality gives you confidence in their products.
Tip: Buy bolts from manufacturers with ISO certifications and certified labs. These show they care about safety and quality.
Manufacturers don’t just test bolts—they check every step of production. From picking materials to delivering bolts, they aim for the best. This ensures bolts work well, even in tough conditions.
Knowing how manufacturers ensure quality helps you choose better bolts. Trusting certified manufacturers keeps your projects safe and dependable.
Bolt fasteners are important in construction, cars, and factories. They keep structures and machines safe and strong. Picking the right bolt means thinking about material, strength, and thread type. This choice affects how well your project works and lasts.
Pro Tip: Unsure about bolts? Ask experts or reliable makers. They can help you choose the best fasteners for your needs.
Learning about bolt types and uses helps you pick wisely. This makes your work safer and more dependable.
Bolts require a nut for tightening, while screws create their own threads in materials. Bolts are used for heavy-duty tasks, and screws are better for lighter jobs. You’ll often see bolts in construction and screws in furniture assembly.
Pick the material based on the environment and load. Stainless steel resists rust, making it ideal for outdoor use. Carbon steel offers higher strength for heavy-duty applications. Always match the material to your project’s needs.
You can reuse bolts if they show no signs of wear, rust, or damage. However, high-stress applications may weaken bolts over time. Always inspect bolts carefully before reusing them to ensure safety and reliability.
Bolt grades indicate strength and durability. Using the wrong grade can lead to failure under stress. For example, Grade 2 bolts suit light tasks, while Grade 8 bolts handle heavy loads. Always check the grade markings before use.
Common tools include wrenches, sockets, and Allen keys. The tool depends on the bolt head type. For example, hex bolts need a wrench, and socket head bolts require an Allen key. Using the right tool ensures proper tightening.
