• What shear strength is
• How shear strength is different from tensile strength
• Shear bolts and their characteristics
• How to calculate bolt shear strength

What Is Shear Strength?

Broadly speaking, shear strength is the maximum stress a material can withstand before it fails in shear. It鈥檚 a measurement used in a number of engineering applications.听听

When you apply that definition to bolts, shear strength is a measure of a bolt鈥檚 ability to resist forces that attempt to slide it apart.听

This is a critical component in applications where bolts are subjected to loads that don鈥檛 act along the axis of the bolt but rather across it, like in joints that experience lateral forces (sliding away from each other in opposite directions).听

Failure in shear can have destructive results 鈥斕齮hink structures collapsing, heavy machinery malfunctioning 鈥斕齭o it鈥檚 important that engineers carefully consider the shear strength of bolts in their designs.

Shear Strength vs. Tensile Strength

Shear strength and tensile strength are both essential measures of how well a bolt can withstand force without breaking. The difference between them is that shear strength measures a bolt鈥檚 resistance to sliding forces, and tensile strength refers to its ability to withstand pulling forces along its length, or axis.

Tensile strength is often higher than shear strength for the same bolt, as all materials are generally stronger in tension than in shear. Think about it: a bolt subjected to a large tensile load will elongate until it eventually snaps. A bolt under a large shear load will fail, or snap, along its cross-sectional area. There鈥檚 simply less wiggle room.

In practice, it鈥檚 important to know the difference between these two strengths and choose the right one to focus on for your application. In structural joints where shear forces dominate, choosing a bolt with high shear strength is more critical than selecting one with high tensile strength.

What Is a Shear Bolt?

A shear bolt is a specialized fastener designed specifically to fail in shear at a predetermined force. This type of bolt is commonly used in applications where controlled failure is necessary to protect more critical components of a system. It will help to avoid more significant damage and costly repairs, as it can be easily replaced after a failure.听

Some key characteristics are:听

• Precise shear point: The bolt is designed to shear, or break, at a specific load to prevent damage to more expensive or vital components.
• Low-tensile material: The bolt is likely made from materials with low tensile strength to ensure they fail at the desired shear load.
• Application-specific design: The bolt is tailored to specific applications where predictable shear failure is a safety feature.

You鈥檒l often find shear bolts in agricultural machinery, snow blowers, and certain types of industrial equipment.

Examples of High Shear Strength Bolts

Standard bolts can have a good amount of shear strength. However, for applications requiring exceptionally high shear strength, you鈥檒l want to choose any of these high shear strength bolts:

• Grade 8 bolts: Known for their high shear strength and tensile strength, Grade 8 bolts are commonly used in heavy machinery, automotive applications, and structural connections. They鈥檙e made from carbon alloy steel, quenched, and tempered for added strength.
• A490 bolts: A490 bolts (from ASTM A490) are used in structural connections 鈥� most often construction applications 鈥� and are known for their high shear strength.听
• Inconel bolts: Inconel is a nickel-chromium-based superalloy. Bolts made from Inconel have extreme shear strength, particularly in high-temperature environments. Therefore, they鈥檙e most often used in aerospace and high-performance automotive applications.
• Stainless steel bolts: While not the strongest in tensile strength, certain grades of stainless steel bolts offer excellent shear strength and are used in marine, aerospace, and chemical processing industries.

How to Calculate Shear Strength

Surprisingly, there are no shear strength values or requirements in ASTM specifications like there are for other strength measurements (e.g. tensile strength). Instead, the articulates shear strength as about 60% of the minimum tensile strength.

So, if a Grade 8 bolt has a minimum tensile strength of 150,000 psi, the shear strength would be 90,000 psi.

Bolt Shear Strength Chart

Here are some more shear strength values, plus their respective tensile strength equivalents, for common bolt grades.

Please note that these values are general guidelines and may vary based on specific material properties and manufacturing processes. You should always cross-check with manufacturer specifications or precise measurements.听

Looking for High-strength Bolts?

Whether you鈥檙e working with high shear strength bolts or calculating shear strength for a specific application, hopefully this article gave you some practical insights. If you have further questions or are interested in ordering high-strength fasteners, get in touch. We鈥檙e happy to make you a quote or steer you in the right direction.

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What Is a Screw Drive?

The screw drive is the mechanism by which the screw head is designed to be turned. It can be a groove or recess, or it can be the shape of the head itself. It’s what allows a screwdriver, wrench, or other tool to engage and turn the fastener.

Choosing the appropriate screw drive type is important because it determines which type of fastening tool must be used to install and remove a screw, as well as the amount of torque that should be applied for ideal joint tension.

See the full anatomy of a screw in this blog article.

Internal vs. External Screw Drives

There are two overarching types of screw drives: internal and external.

Internal Screw Drives

Internal drives are either cut or stamped into the screw’s head and are most commonly slotted, Philips, or hex. Utilizing tools like a screwdriver, Allen wrench, or drill, these screws require a fitting instrument to insert into their respective head to facilitate fastening or loosening.

Some more specific types of internal screw drives include (but aren鈥檛 limited to):

• Phillips head听
• Slotted head
• Socket head

External Screw Drives

External drives require a tool that wraps around the screw head, like a wrench or a torque wrench.

Some more specific types of external screw drives include (but aren鈥檛 limited to):听

• Hex head
• Hex flange head
• Square head

3 Factors to Consider When Choosing Screw Drives

So how do you choose which type of screw drive is best for your application? Here are some starting points to consider.听

1. Torque requirements

Torque is the rotational force applied to a screw. Different applications require different levels of torque to withstand operating conditions.听 In general, you can apply more torque with an external drive than an internal drive, as you risk stripping an internal drive if you apply too much torque.听

First, evaluate the torque requirements of your specific application, then choose a screw drive system that can provide the necessary torque to meet those demands without exceeding them. Because too much torque can be just as bad as not enough torque.听

2. Ease of use and installation

Consider the ease of installation, maintenance, and overall usability of the screw drive type in your application. Is it easier to turn in or crank around the screw head? What tools do you have at your disposal?听

3. Industry standards and specifications

Industries often have specific standards, specifications, or best practices that must be adhered to for safety, performance, and compatibility reasons. Do your research and adhere to any requirements that apply to your application when choosing a screw drive type.听

Non-compliance could lead to performance issues or safety concerns.

Other Screw Head Terminology to Know

You can also categorize screw head types as countersunk or non-countersunk.听

• Countersunk is when the head rests evenly with the material surface after installation
• Non-countersunk is when the head protrudes from the material surface after installation. In other words, the head is exposed.

These features can also affect the tool required for installation and removal, assembly efficiency, and torque transmission.

Request a Custom Screw Quote

At 黑料大事记, we can manufacture screws with the following head types: hex, square, round, Place, slotted (sometimes), and hex flange (sometimes). See our full capabilities statement here.

If you need a custom solution for your application, we鈥檙e happy to help. Manufactured right here in Michigan, we can assure quality throughout the entire manufacturing process and great customer service even beyond that.

Request a quote online or get in touch to learn more.听

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Below we explore the world of washers, when they鈥檙e needed, and when they鈥檙e not needed.

What Are Washers and How Do They Work?

A washer is a type of fastener used to distribute the load of a threaded fastener, such as a bolt or a screw, over a larger surface area. It is typically a flat, thin, disc-shaped piece made from materials like metal, plastic, rubber, or fiber. Washers are often used in combination with nuts and bolts or screws to prevent damage to surfaces, reduce friction, and prevent loosening.

There are several types of washers, each designed for specific purposes. Some common ones are:听

• Flat Washers: These are simple flat washers with a hole in the center. They are used to distribute the load and prevent the fastener from digging into the material’s surface.
• Lock Washers: Lock washers have a design that provides resistance against loosening due to vibrations or other forces.听
• Spring Washers: These are curved or wavy washers that provide spring-like tension, maintaining pressure between the fastener and the material. They help compensate for loosening due to thermal expansion or vibration.
• Conical Washers: Conical washers resemble a curved cone shape. They are known to provide controlled spring tension and maintain a consistent load or pressure between two surfaces.

Factors Influencing the Need for Washers

Washers are great, but they aren鈥檛 always necessary. The decision to use washers depends on the specific needs and characteristics of your application. Some key factors that influence when to use washers and when not to include:听

• Material, of both the washer and the material being fastened.听
• Uneven surfaces and gaps. Using a washer can help create a more even contact between the fastener and the material.听
• Environmental factors like corrosivity, temperature, and vibration.听
• Specific application requirements. Some applications have unique requirements like thermal expansion compensation, electrical insulation, or pressure sealing.
• Aesthetics. In some cases, decorative washes may be used to enhance the appearance of a fastened joint.

When to Use Washers vs. When NOT to Use Washers

All that said, washers can be useful in a number of applications but aren鈥檛 necessary in all of them. And when a washer isn鈥檛 necessary, it鈥檚 best to avoid the additional product, time, and expense.

Here鈥檚 a breakdown of when to use washers and when not to:听

When to Use Washers

• You need better load distribution
• Your bolt and nut assembly isn鈥檛 tight enough
• You don鈥檛 want the head of the fastener to punch through the hole
• Your fastening needs to be waterproof
• You need additional spacing or gap filling

When Not to Use Washers

• You have uniform material; fastened components are the same material, and there are no concerns with surface damage
• Your fastener has a large bearing surface
• Vibration and other environmental factors aren鈥檛 a concern
• Your joint has limited space for a washer
• You can use a Place bolt instead
  

A More Effective & Efficient Locking Mechanism: Place Bolts

Place bolts are self-locking, free-spinning hex head bolts. Their heads are responsible for their locking action, which prevents loosening due to vibration听鈥斕齯p to seven times that of conventional hex head cap screws.听

What are we getting at here? Place bolts eliminate any need for washers, even in high-vibration environments. They lock and distribute loads on their own, so you don鈥檛 need to worry about stocking, installing, and paying for washers.听

Learn more about Place bolts in previous blog articles:

• What Is a Self-Locking Bolt, and How Does It Work?

• What Are Place Bolts Used For?

• How Asymmetric Place Bolts Work

Purchase Place Bolts at 黑料大事记

If your application could benefit from Place bolts, get in touch with our team. We manufacture per-spec Place bolts, guaranteed to meet your requirements and provide outstanding vibration resistance without the need for additional washer solutions.听

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The post What to Know About Zinc-Nickel Plating for Fasteners appeared first on 黑料大事记.

In this article, we鈥檒l discuss a few general methods of bolt manufacturing, as well as give you an inside look at the step-by-step process we use to manufacture a bolt here at 黑料大事记.听

How Is a Bolt Made? 3 Common Methods

Before diving into a real-world bolt manufacturing example, let鈥檚 first recap the three most common methods of manufacturing bolts: cold forming, hot forging, and machining.

• Cold forming (AKA cold heading) is the process of forming a bolt without heating up steel. This is done by striking or pressing the material within a form.
• Hot forging is the process of heating up steel to a point where it becomes malleable, then forming it in a die.
• Machining is the process of cutting away steel to fit desired bolt dimensions.听

Each of these methods has its own advantages and disadvantages, so one may be more suitable for a particular application than another. For instance, we typically use cold forming at 黑料大事记 because it suits materials like alloy and carbon steel wonderfully and strengthens them through a process called 鈥渨ork hardening.鈥澨�

Read more about these common bolt manufacturing methods here.听

The Bolt Manufacturing Process: A Step-by-Step Guide

Now let鈥檚 look at one of these bolt manufacturing processes in action. As we mentioned above, we primarily use cold forming at 黑料大事记, so we鈥檒l use a cold-formed bolt as an example.听

The bolt we鈥檒l look at here is a hex flange bolt with a 1鈥� diameter. It鈥檚 made of alloy steel. Here are the seven steps we take to manufacture it, along with pictures from throughout the production process. Keep in mind that this is a part that requires a few more steps in the production process than others due to its shape and diameter.听

1. Cutoff

Our team takes bars of steel and cuts them to length.听

2. Extrude

This is our first hit. We strike each piece of cut material (one at a time) within a large press to reduce the diameter on one end to the pitch diameter that is specified. That鈥檚 where the threads will be formed in a future step.

The other end (with the larger diameter) is where the bolt鈥檚 head will be. During this step, it gets a small increase in diameter to prepare for the next hit.

3. Upset

This is our second hit, where we strike the material within the press again (also one at a time). The goal here is to enlarge the bolt鈥檚 head end, so it鈥檚 ready for the final hit that will form it. The material doesn鈥檛 typically flow well enough to form the head in just one hit.听

4. Headed

This is our third hit, which is also done one at a time in a press. The hex, flange, undercut, and head markings are all formed during this stage.

5. Trimmed

This is our fourth and final hit. It鈥檚 done in a trimming press, one at a time. This is when the flange is trimmed, making it straight and round.听

6. Rolled

During this stage, we roll the bolt鈥檚 threads. While some manufacturers may choose to cut threads, we stick with thread rolling at 黑料大事记. Rolled threads are typically more durable, accurate, and resource-efficient.听

The threads are added using a reed roller, again one at a time. This is a very intensive part of the bolt manufacturing process.听

Once the threads are all rolled, the bolt is dimensionally done and ready for final dimensional inspection. This is when our team ensures all the dimensions are in tolerance.听

7. Finished

During this stage, we send the bolt (and all the others in the order) off to a partner for heat treatment, blasting, and zinc plating. We don鈥檛 do in-house finishing or plating at 黑料大事记.

After the bolts have been heat-treated, blasted, and plated, we get them back, and they鈥檙e almost finished. But before they鈥檙e ready to pack and ship, we re-roll the threads one more time. This is to remove any nicks or burrs that may have been added in the heat treat or plating process, and to ensure that the threads gauge properly.听

From there, the bolts go through one final inspection to ensure everything is as it should be. Then it鈥檚 time to pack and ship!

Looking for a Quality Bolt Manufacturer? Choose 黑料大事记.

黑料大事记 is your trusted source for high-quality, custom fasteners in limited-run quantities. Our production and testing processes ensure you get the exact fasteners you need, every time. If you need a bolt, screw, or stud manufactured to your specifications, please reach out! We鈥檇 love to discuss how we can help.

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