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At 黑料大事记, we鈥檙e proud to utilize this technique to produce high-quality carbon steel and alloy fasteners. We know all the ins and outs of cold forming and are here to give you the inside scoop.聽

What Is Cold Forming?

Cold forming, also called cold heading, is a common manufacturing process that produces steel bolts and fasteners. Unlike methods that involve heating the steel, cold forming achieves shaping without using high temperatures. Instead, it relies on applying force through striking or pressing steel within a die, ultimately sculpting the metal into the desired dimensions.

Compared to alternative manufacturing methods such as hot forging and machining, cold forming stands out for its ability to bolster strength and minimize waste. Hot forging reduces waste and has fewer size and shape limitations, but it doesn’t enhance strength to the same degree as cold forming. Machining, on the other hand, excels in producing complex shapes but generates significant waste and may compromise the strength of the final product.

What Are the Key Benefits of Cold Forming?

Cold forming offers many advantages that ensure high-quality, reliable products.聽

1. Enhanced Strength Through Work Hardening

Cold forming can significantly bolster the strength of bolts and fasteners. This is achieved through a process called work hardening, where the steel is meticulously shaped without the need for cutting or heating. As a result, the grain structure of the steel remains intact and seamlessly flows with the contours of the part, contributing to increased strength and durability.

2. Elimination of Scrap and Material Savings

While traditional manufacturing methods can result in considerable material waste, cold forming minimizes scrap and promotes efficient material usage. By shaping the material into the desired form without removing any material, cold forming drastically reduces waste, leading to substantial material savings and cost reductions.

3. Dimensional Accuracy and Part Consistency

Cold forming helps meet stringent quality standards with precision. The process allows for the creation of fasteners with uniform dimensions and exact specifications, ensuring reliable performance and compatibility across various applications.

4. Improved Surface Finish and Reduced Secondary Operations

The precise shaping achieved through cold forming results in smooth surfaces and clean edges, eliminating the need for time-consuming secondary operations like polishing or grinding. This saves time and resources and enhances the aesthetic appeal of the final product.

What Parts Are Made by Utilizing Cold Forming?

Cold forming can be used to create a wide array of essential parts across various industries.

• Fasteners – Bolts, screws, studs, nuts, and rivets for many different industries are among the primary components manufactured through cold forming.聽
• Electronic housings and electrical contacts – The precision and accuracy offered by cold forming make it ideal for shaping electronic housings and electrical contacts, ensuring seamless functionality in electronic devices and systems.

From medical devices to aerospace components to consumer products, cold forming thrives when it comes to producing small parts. However, it’s also important to note its versatility in handling larger components.聽

At 黑料大事记, our presses enable us to cold form parts with diameters up to 1-1/8″, showcasing the breadth of possibilities this manufacturing process offers.

Cold forming isn’t just limited to standard shapes and configurations. It also enables the creation of intricate designs and features, including the following:聽

• Threads – Cold forming facilitates the creation of precise threads, ensuring seamless integration with mating components and enhancing the overall integrity of assemblies.
• Knurls, heads, chamfers, grooves, tapers, and undercuts – Whether it’s adding texture for improved grip or incorporating specialized features for enhanced functionality, cold forming allows for the precise shaping of various details to meet specific requirements.

Discover How 黑料大事记 Utilizes Cold Forming

We’ve embraced cold forming at 黑料大事记 for manufacturing carbon steel and alloy steel fasteners. This technique aligns perfectly with our commitment to delivering superior quality, precision, and reliability.

By utilizing cold forming, we ensure that our fasteners exhibit exceptional strength, dimensional accuracy, and consistency. The process enhances the structural integrity of our products through work hardening, where the steel’s grain structure remains intact, resulting in unparalleled durability and reliability.

Our cold-formed fasteners are used for applications across a diverse range of industries, including but not limited to the following:聽

• Automotive industry – Automotive manufacturers trust our cold-formed fasteners for engine components, suspension systems, and chassis assemblies.聽
• Military Ground Vehicles – Our cold-formed fasteners play a vital role in military ground vehicle construction and maintenance. They meet the rigorous demands of these applications, contributing to the safety and performance of military vehicles.
• Heavy machinery – With their exceptional strength and reliability, our fasteners contribute to the effectiveness and safety of heavy machinery, ensuring reliable performance in various industrial applications worldwide.

黑料大事记 黑料大事记 for Exceptional Fastening Solutions

黑料大事记 us today to learn more about our innovative manufacturing processes, extensive product offerings, and how we can meet your needs and requirements. Whether you’re in the military, automotive, heavy machinery, or any other industry, trust 黑料大事记 to deliver reliable, high-quality fasteners that exceed your expectations.

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Wondering which one may be best for your application? Let’s take a look at rolled threads vs. cut threads, examine the differences between them, and identify what advantages and disadvantages each brings to the table.

What Are Rolled Threads?

Rolled threads are formed by pressure. Basically, the fastener is rolled through a set of threading dies that displace the material to form threads, without removing any of the material or changing its grain structure. Roll threading is a cold forming process, meaning there鈥檚 no heat added to transform the part.

Advantages of Rolled Threads

Rolled threads come with many advantages in terms of performance and efficiency. Here are a few of them:

• Enhanced strength – When a material is shaped without being cut or heated, it maintains the grain structure of the steel, with grains flowing along the contours of the part. This is a process called 鈥渨ork hardening,鈥� which enhances the strength of the part.
• Consistent precision – Thread rolling ensures the most consistent, quality results possible 鈥斅燼nd relatively quickly, too!
• Reduced waste and energy consumption – Since you don鈥檛 need to cut any material and you don鈥檛 need energy to heat any material, thread rolling offers facilities significant time and cost savings.

Disadvantages of Rolled Threads

Although rolled threads are great for many applications, the thread rolling process does have some drawbacks, including:

• Size, shape, and material limitations – As much as thread rolling capabilities have improved over the years, parts with large sizes, unique shapes, and/or unconventional materials aren鈥檛 able to be rolled.
• Rolled from the pitch diameter – Since they鈥檙e rolled from the pitch diameter (a diameter that is halfway between the major and minor diameters of the part), you鈥檒l likely need to form the major diameter for the part鈥檚 body, and then form the pitch diameter for its threaded component. This extra step isn鈥檛 usually a huge deal, but it is something to take into account during the manufacturing process.

RELATED: Need a specialty bolt, screw, or stud? 黑料大事记 can help.

What Are Cut Threads?

Cut threads are formed through a method of cutting away, or removing, material from a round bar. This is usually done using a threading die or a single-point cutting tool.

Advantages of Cut Threads

There are some facilities that prefer thread cutting, mainly because of the following two advantages:

• Versatile capabilities –聽 Thread cutting is compatible with parts of all specifications, even large diameter sizes. For the large-sized, uniquely shaped parts that thread rolling can鈥檛 typically handle, thread cutting is a suitable alternative.
• Suitable for parts with cavities – In addition to versatility in size and shape, thread cutting is also a suitable choice for parts with cavities, such as pipes.

Disadvantages of Cut Threads

However, as thread rolling processes have advanced over the years, many manufacturers have begun to see more and more disadvantages of thread cutting, including:

• Slower production rates – Thread cutting typically takes a bit longer than thread rolling, which decreases production speed and increases labor costs.
• Reduced strength – Unlike thread rolling, thread cutting doesn鈥檛 allow for any work hardening to occur. Instead, removing material causes changes in the part鈥檚 grain structure 鈥斅爑ltimately resulting in a loss of strength.
• Threatened durability – Cutting threads can easily result in tiny, unwanted tears in the material, which can expand over time and threaten the part鈥檚 longevity.
• High amount of waste – Removing material from parts leads to a lot of waste that needs to be managed. The scraps are also usually pretty nasty and sharp to deal with.

Rolled Threads vs. Cut Threads: Which is Best for My Application?

Based on all that information, you can probably conclude that rolled threads are often the best choice. They鈥檙e consistently more durable, accurate, and resource-efficient than their cut counterparts.

However, there are still some applications where cut threads are beneficial. If you鈥檙e working with large-diameter parts or parts that have cavities, their versatility makes them a more suitable choice.

Find Durable, Thread-Rolled Fasteners at 黑料大事记

At 黑料大事记, we use cold forming and thread rolling to produce durable fasteners. Ideal for a range of applications, we can deliver the quality solution you need based on your unique specifications. Call us or contact us online to get started.

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What Is Cold Forming?

Cold forming, also known as cold heading, is the process of forming a fastener without heating up the material. This is usually accomplished by striking or pressing the material within a form, or die, to create a part with your desired features and dimensions. This high-speed process allows manufacturers to produce large quantities of products quickly, consistently, and cost-effectively.

What Is Cold Forming Used For?

Cold forming is a very common method for manufacturing fasteners of all varieties. It鈥檚 also a trusted manufacturing method for many other applications as well, including (but definitely not limited to):

• Creating large, flat metal sheets
• Folding metal into complex shapes
• Shaping metal tubes
• Forming riveted joints

RELATED: Need a specialty bolt, screw, or stud? 黑料大事记 can help.

Which Materials Can Be Cold Formed?

Cold forming is primarily used to manipulate the shape of metals. , including stainless steel, carbon steel, copper, brass, aluminum, lead, bronze, and various alloys.

However, it鈥檚 important to remember that each of these metals behaves differently 鈥斅爏o while you can cold form them all, some may deliver better results than others, or some may be suited perfectly for a different type of manufacturing process, like machining.

We鈥檝e found that some of the best metals for cold forming 鈥斅爀specially for cold forming fasteners 鈥斅爄nclude alloy steel and low carbon steel.

What Happens During the Cold Forming Process?

The cold forming process is pretty straightforward in theory. You simply place a chunk of material into a form, then strike or press it to form the part.

However, there are a couple of different forming methods that can be used to achieve different results. These include:

• Forward extrusion – A method of pushing the material into a form that has a reduced diameter, so that the material鈥檚 diameter also reduces.
• Backward extrusion – A method of pushing the material into a form with a rod, causing the material to flow back around it. This creates a hollow-shaped hole in the material.
• Upset – A method of forming heads on fasteners. Material is pushed into a short form, then the excess material is upset at the face of the form to create a particular head shape.
• Thread rolling – A method of threading fasteners by rolling the stock of material through dies with external thread-like rollers. These rollers press and contort the material鈥檚 surface to form threading without having to cut away or remove any material.

What Are Some Advantages of Cold Forming?

Cold forming is one of the preferred methods of making special fasteners. Below are a few reasons why:

Reduced Waste

In other manufacturing processes like machining, you have to remove and waste material to achieve your desired outcome. But when you cold form a fastener, you shape the material into its desired form without removing any of the material. This reduces a great deal of waste and improves material utilization.

Fast Production

Cold forming is a high-speed process. In fact, some manufacturers use it to make 100 parts per minute. Better yet, that speed is paired with consistently precise and quality results.

Added Strength

In a process called 鈥渨ork hardening鈥�, cold forming adds strength to the part. When the material is shaped without being cut or heated, it keeps its grain structure. The grains flow along the contours of the part, which adds strength to the part.

Reduced Energy Consumption

Unlike hot forging, cold forming requires no additional energy to heat the material before production.

What Are Some Disadvantages of Cold Forming?

Although it鈥檚 a great process for many applications, cold forming does have some drawbacks to keep in mind, including:

Size Limitations

The bigger the diameter of a fastener, the more pressure is needed to press material into its desired shape. If you had a big enough machine, you could produce fasteners of any size. However, this isn鈥檛 usually feasible, so some considerably large fasteners must be hot forged.

Shape Limitations

As much as cold forming capabilities have improved over the years, some specialty parts with unique shapes can鈥檛 be formed without cutting material. Therefore, they鈥檙e more suitable for the machining process.

Material Limitations

As mentioned above, some materials lend themselves better to cold forming than others. Although it鈥檚 possible to use a variety of metals, sticking to the most effective types will give you better results.

Discover Cold Forming at Its Best by Working with 黑料大事记

黑料大事记 primarily uses cold forming to make specialty, limited-run bolts, screws, and studs. However, our team knows that different situations require different manufacturing methods, so we also employ machining techniques for applicable projects. 黑料大事记 our team today to learn more about our products and manufacturing processes.

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If you鈥檝e ever wondered what those screw and bolt head markings mean, or if there鈥檚 some overarching logic to them, you鈥檙e in the right place. In this article, we鈥檒l give you an overview of the following:

Manufacturer Screw and Bolt Head Markings
Fastener Standard Screw and Bolt Head Markings
Examples of Screw and Bolt Head Markings & What They Mean

What Do Screw and Bolt Head Markings Mean?

Screw and bolt head markings identify the manufacturer of the fastener and the standard to which the fastener was made. Below, we鈥檒l explore both of those concepts, then connect them together with a few examples.

Manufacturer Screw and Bolt Head Markings

The mandates that manufacturers must mark each fastener with their unique company symbol to identify that they made it 鈥� the only exception being fasteners that are too small to mark. Every company that has registered its specific screw and bolt head marking can be found in . Simply click the little PDF symbol next to the latest version, and you鈥檒l be able to view the list for free.

Because each fastener is uniquely marked by its maker, the part can be easily traced back to its manufacturer should a problem occur. This traceability serves to instill a sense of accountability in the manufacturer and a sense of confidence in the end user.

As an example of a manufacturer screw and bolt head marking, the unique identifier for us at 黑料大事记 is the letter combination WG. Appearing on the head of a bolt or screw, it would look something like the image to the right.

Fastener Standard Screw and Bolt Head Markings

Over the years, different organizations have come together and attempted to bring some order to the fastener industry by releasing standards that provide specifications for certain types of fasteners. These specs can cover anything from material composition, to dimensional tolerances, to plating. For example, the American Society of Mechanical Engineers (ASME) has a document called ASME B1.1 that provides requirements for unified inch screw threads.

There are all sorts of standards for all sorts of fasteners 鈥斅營SO, IATF, SAE, ASTM, ASME, etc. How important is a particular standard? It depends on how many people decide that it鈥檚 important. Some, like ASME B1.1 mentioned above, are universally accepted and used. Others are a bit more obscure, or are intended to service a limited segment of the industry.

Interested in learning about some other fastener standards? Check out our blogs on ISO standards or bolt grades.

Some fastener standards create classes or grades for fasteners by laying out material and physical requirements that a fastener must meet. A common example is SAE J429, which lays out requirements for many common fastener grades, such as Grade 2, Grade 5, and Grade 8 鈥斅爓hich all begin to work as some kind of shorthand terminology for fasteners. When you know a fastener is Grade 5, for instance, you automatically know many details about it, including things like:

• Materials it鈥檚 made out of
• Its hardness range
• Its strength characteristics
• If it鈥檚 an inch or metric part

How does this all relate to screw and bolt head markings? Well, most fastener standards that introduce classes and grades have screw and bolt head marking requirements. The class and grade identifiers combine with the manufacturer鈥檚 head marking to comprise the jumble of stuff you鈥檒l find on most fastener heads.

Examples of Screw and Bolt Head Markings & What They Mean

Now let鈥檚 put all this information together. We鈥檒l do so by returning back to SAE J429, a standard established by The Society of Automotive Engineers (SAE). In a nutshell, this standard lays out mechanical and material requirements for inch bolts, screws, studs, sems, and U-bolts in sizes up to 1-陆鈥� in diameter.

But the main thing to focus on here is that the standard introduces a grading system based on numbers, where increasing numbers indicate increasing strength 鈥斅爏o a Grade 5 has a higher tensile strength than a Grade 2. And those grades are shown on the head markings of a bolt. While SAE J429 standard designates many grades, we鈥檒l focus on three of the most commonly used below.

SAE J429 Grade 2 Bolt Head Marking

Our first example is a bolt head marking that looks like this:

Wait a minute! There鈥檚 no grade marking on this bolt! You just reused the image from before! Well, that鈥檚 true 鈥斅爓e did just reuse the image from before, but we did it because Grade 2 bolts don鈥檛 have a head marking requirement.

So if there鈥檚 no head marking requirement, how can you know when a bolt is a Grade 2 and when it鈥檚 something else? The answer is: we don鈥檛 know. A lack of a grade identifier will tell you that a bolt ISN鈥檛 one of the myriad of other classes and grades 鈥斅燽ut in order to be sure of exactly what it IS, you鈥檒l need to verify the material.

Once we鈥檝e established the bolt is a Grade 2, you now know two important things. You know that the bolt is an inch-series bolt, and you know what its minimum tensile strength is 鈥斅爓ell, once you know the diameter of the bolt, that is. Here are some of the minimum tensile strengths for Grade 2 bolts, based on diameter:

• Diameters of 录 – 戮鈥� = minimum tensile strength of 74 ksi
• Diameters of 戮 – 1 陆鈥� = minimum tensile strength of 60 ksi

Bolts with these tensile strengths would be considered low-strength bolts. These strengths can generally be achieved without heat treating the parts.

SAE J429 Grade 5 Bolt Head Marking

Our second example actually has a grade head marking:

So, as you can see, this bolt head has 黑料大事记鈥檚 manufacturer mark and three radial lines. These lines indicate that the bolt is a Grade 5. Here are some of the minimum tensile strengths for Grade 5 bolts, based on diameter:

• Diameters of 录 – 1鈥� = minimum tensile strength of 120 ksi
• Diameters of 1 – 1 陆鈥� = minimum tensile strength of 105 ksi

Grade 5 bolts are considered to be medium-strength fasteners. They鈥檙e required to be heat-treated, quenched, and tempered in order to gain the desired strength.

SAE J429 Grade 8 Bolt Head Marking

Finally, our last example from SAE J429:

Here, we have a bolt head marking with the 黑料大事记 manufacturer identifier and six radial lines. These six radial lines indicate that the bolt is a Grade 8 bolt.

*Note:聽You may notice that in the images the WG identifier has been moved around a bit to accommodate the grade markings. This is a totally legitimate practice. Many times with smaller diameter fasteners, you鈥檙e trying to fit all the required markings on the head while keeping them legible 鈥斅爏o you move things around to fit them as best as you can. For the SAE J429 standard, placement of the lines is important, so we move the WG around as necessary. For many other standards, you鈥檙e free to move all markings around as needed.

Back to Grade 8. Grade 8 bolts have a minimum tensile strength of 150 ksi for all diameters from 录 – 1 陆鈥�. They鈥檙e considered to be high鈥搒trength fasteners, and they need to be heat-treated, quenched, and tempered in order to reach the desired strength.

So there you have it 鈥斅燼 quick overview of the key grades from SAE J429 and their head markings. As a quick summary:

• No marking – Grade 2
• Three radial lines – Grade 5
• Six radial lines – Grade 8

Learn More About Screw & Bolt Head Markings with 黑料大事记

Interested in learning a bit more about screw and bolt head markings? We talk about three additional standards that deal with inch-series fasteners in this blog. Or, we also talk about some metric head markings in this blog. Check them out.

And if you have any questions that these blogs can鈥檛 answer for you, feel free to reach out to us. With plenty of experience in the fastener industry, we鈥檒l likely have an answer for you. Give us a call at (800) 656-2658 or contact us online.

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While SAE J429 Grades 2, 5, and 8 are probably the most common inch-series fastener specifications that we deal with here at 黑料大事记, there are plenty of other ones with their own grades and head markings.

In this article, we鈥檒l take a look at three standards from ASTM:
1. ASTM A307 Bolt Grade Markings
2. ASTM A193 Bolt Grade Markings
3. ASTM A354 Bolt Grade Markings

What Are ASTM Fastener Standards?

ASTM stands for the American Society for Testing and Materials. This organization has established various standards and specifications for fasteners like bolts and studs. Each of these standards introduces different grading systems based on letters, numbers, and combinations of both 鈥斅爐hink A, B, BC, B7, etc. These grades generally determine different tensile strengths.

Examples of ASTM Bolt Grade Markings

So, now let鈥檚 put this information together and discuss what some of the different ASTM fastener standards have to say about bolt grade head markings.

ASTM A307 Bolt Grade Markings

is a specification that creates three grades of bolts and studs: Grade A, Grade B, and Grade C 鈥斅燽ut Grade C has been replaced by a different standard, so we鈥檒l ignore it here. ASTM A307 covers diameters 录鈥� to 4鈥�. The grades are again differentiated by tensile strength, although the spec also differentiates by intended use.

ASTM A307 Grade A

Here鈥檚 what an ASTM A307 Grade A bolt head marking would look like:

Grade A bolts and studs have a minimum tensile strength of 60 ksi and are intended for general applications. If you鈥檙e like us and have trouble remembering numbers, you鈥檒l appreciate this head marking, because it includes the number of the spec.

Grade A bolts and studs are considered to be low-strength, having a tensile strength roughly equivalent to SAE J429 Grade 2. It鈥檚 generally not necessary to heat treat Grade A parts in order to meet the minimum tensile requirements.

ASTM A307 Grade B

The head marking for a Grade B bolt can be seen here:

Yep, this is pretty much what we expected. Once again, the number of the spec is right there on the head if you need it, which is nice.

Grade B bolts and studs have a tensile strength between 60 ksi and 100 ksi. Their intended use is in flanged joints in piping systems with cast iron flanges. The major difference between Grade B and Grade A is that Grade B has minimum and maximum tensile strength requirements set by the spec, while Grade A only has a minimum tensile strength requirement.

ASTM A193 Bolt Grade Markings

is a specification that creates a rather large number of grades for inch-series bolts, screws, and studs up to seven inches in diameter.

As the title would lead you to believe, this spec deals with fasteners intended for use in high-temperature or high-pressure environments. It provides guidelines for six grades for parts made of ferritic (carbon or alloy) steels and more than twenty grades for parts made of austenitic stainless steels. There鈥檚 also a version of the standard, ASTM A193M, which lays out guidelines for metric-series fasteners.

But for the sake of brevity, let鈥檚 just take a look at the most common ASTM bolt grade that 黑料大事记 manufactures: Grade B7.

ASTM A193 Grade B7

Grade B7 bolts are made from alloy steel. While there鈥檚 a metric version of Grade B7 that can be found in ASTM A193M, we鈥檙e sticking to the inch-series version here.

Here we see the grade stamped into the bolt head marking. You may have noticed that this standard requires only the grade to be marked, while the previous standard we covered, ASTM A307, required the number of the standard along with the grade. The more you look at these things, the more you鈥檒l notice that each standard, even standards written by the same organizations, tend to handle head markings a little differently.

Grade B7 bolts have a minimum tensile strength of 125 ksi for diameters 2 陆鈥� and under, 115 ksi for diameters over 2 陆鈥� through 4鈥�, and 100 ksi for diameters over 4鈥� through 7鈥�. These minimum tensile strengths are roughly equivalent to the requirements for SAE J429 Grade 5. Therefore, these parts are considered to be medium-strength. Grade B7 parts are required to be heat-treated, quenched, and tempered.

ASTM A354 Bolt Grade Markings

is a specification that lays out the guidelines for two grades: Grade BC and Grade BD. All parts in this standard must be made from alloy steel and be heat-treated, quenched, and tempered. This spec covers parts up to 4鈥� in diameter.

ASTM A354 Grade BC

Let鈥檚 take a look at the bolt head marking for Grade BC:

Again, we simply have the grade itself marked. Grade BC fasteners have a minimum tensile strength of 125 ksi for diameters 录鈥� through 2 陆鈥�.聽 The minimum tensile strength is 115 ksi for diameters over 2 陆鈥� inches. Generally, Grade BC parts are considered to be medium-strength fasteners.

ASTM A354 Grade BD

The bolt head marking for Grade BD is shown here:

No surprises here. Grade BD parts have a minimum tensile strength of 150 ksi for diameters 录鈥� through 2 陆鈥� and 140 ksi for diameters over 2 陆鈥�. Grade BD parts are considered to be high-strength. The mechanical properties of Grade BD fasteners in diameters 录鈥� through 2 陆鈥� are almost identical to those of SAE J429 Grade 8 鈥� so similar, in fact, that we鈥檝e got one more 鈥渂onus鈥� bolt head marking to show you.

ASTM A354 Grade BD vs. SAE J429 Grade 8 Bolt Head Markings

Whoa! Are those Grade BD AND Grade 8 markings? That鈥檚 right 鈥斅爐he mechanical properties of Grade BD are so close to SAE J429 Grade 8 that ASTM A354 allows you the option to include both grade identifiers if you wish. Therefore, the same fastener can qualify and be marked for both Grade BD and Grade 8. Of course, this begs the question: Why do ASTM Grade BD and SAE J429 Grade 8 both exist?

Well, SAE J429 only covers diameters up to 1 陆鈥�, and ASTM A354 covers parts up to 4鈥�. So ASTM A354 allows for larger fasteners to be covered in the same standard as smaller ones.

RELATED: Need a specialty bolt, screw, or stud? 黑料大事记 can help.

Learn More About Bolt Head Markings with 黑料大事记

Interested in learning a bit more about bolt head markings? We give an overview of what bolt head markings mean and provide some more inch-series examples from SAE J429 in this blog. Or, we also talk about some metric head markings in this blog. Check them out.

And if you have any questions that these blogs can鈥檛 answer for you, feel free to reach out to us. With plenty of experience in the fastener industry, we鈥檒l likely have an answer for you. Give us a call at (800) 656-2658 or contact us online.

The post Understanding a Few Common ASTM Inch-Series Bolt Grade Markings appeared first on 黑料大事记.

We鈥檝e talked about how to use head markings to determine the different grades and manufacturers of inch-series bolts, but metric bolt and screw head markings are a whole different beast.

They鈥檙e not a beast we can鈥檛 tackle though. Let鈥檚 walk through how to decipher metric bolt and screw grades, plus their head markings, using one ISO standard and its following property classes as examples:

ISO 898-1 Property Class 8.8 Metric Bolt and Screw Head Marking
ISO 898-1 Property Class 10.9 Metric Bolt and Screw Head Marking
ISO 898-1 Property Class 12.9 Metric Bolt and Screw Head Marking

What Are Metric Fasteners?

Before we discuss the major metric spec we use at 黑料大事记, ISO 898-1, let鈥檚 first explain metric fasteners in general. It鈥檚 important to be aware that metric fasteners are a part of a completely different system than inch-series fasteners. Metric fasteners have different units of measurement, different threads, and different specs.

Therefore, you can鈥檛 necessarily 鈥渃onvert鈥� parts back and forth from metric to inch series, and vice versa. There are rough equivalents and points of overlap 鈥斅爁or example, an M6 and a 录鈥� bolt are roughly the same diameters, and an M10X1.50 nut can be threaded onto a 鈪�-16 bolt 鈥斅燽ut the systems are separate from one another.

Metric Terminology: Grade vs. Property Class

What鈥檚 a property class? Simply put, it鈥檚 the metric equivalent of a grade in inch-series terminology. One nice thing about ISO 898-1 is that the property class number designations have a concrete meaning. In SAE J429 grades like Grade 2 and Grade 8, the 鈥�2鈥� and 鈥�8鈥� don鈥檛 actually refer to anything 鈥� but with ISO 898-1 property classes, the number designations refer to real numbers.

That said, a property class designation consists of two numbers separated by a dot. Here鈥檚 what those numbers mean:

• The first number is 1/100th of the part鈥檚 nominal tensile strength in megapascals (MPa).
• The second number is 1/10th of the percentage of the part鈥檚 nominal yield strength compared to the part鈥檚 nominal tensile strength.

So, in English, a Property Class 8.8 bolt is a bolt with a nominal tensile strength of 800 MPa and a nominal yield strength that is 80% of that nominal tensile strength, so 640 MPa.

*Note: You probably noticed the use of the word 鈥渘ominal鈥� quite a bit in the last couple of sentences. That鈥檚 because the strengths indicated in the numbering system are meant to be ballpark figures and not necessarily the exact required strengths.

Alright, let鈥檚 jump into the spec.

ISO 898-1 Metric Bolt and Screw Head Markings

is the only spec we鈥檙e going to talk about here because it鈥檚 by far the most commonly used metric spec for fasteners. This standard covers bolts, screws, and studs made from carbon steel and alloy steel, and it lays out the requirements for ten different property classes.

Interested in learning about ISO standards for fasteners? Check out this blog.

Of ISO 898-1鈥檚 ten property classes, let鈥檚 focus on just three of them: Property Classes 8.8, 10.9, and 12.9. We鈥檒l discuss what their metric head markings look like, and what some of their tensile strength requirements are.

ISO 898-1 Property Class 8.8 Metric Bolt and Screw Head Marking

Let鈥檚 first look at a Property Class 8.8 head marking:

One thing that鈥檚 nice about the ISO 898-1 property class designations is that the approximate tensile strength is right there on the bolt head marking. Property Class 8.8 bolts and screws have a minimum tensile strength of 800 MPa for bolts and screws 16mm in diameter and under, and 830 MPa for bolts and screws with a diameter over 16mm.

To give you an idea of how this compares to the strength of inch-series fasteners, 6.9 MPa are about equal to 1 ksi. 800 MPa are about 155 ksi. So a Property Class 8.8 bolt or screw is a medium-strength fastener that鈥檚 roughly the same strength as an SAE J429 Grade 5 fastener.

ISO 898-1 Property Class 10.9 Metric Bolt and Screw Head Marking

The Property Class 10.9 head marking is shown here:

Property Class 10.9 bolts and screws have a minimum tensile strength of 1040 MPa for all sizes. As you can see, they鈥檙e slightly stronger than the nominal value in the property class designation. Property Class 10.9 bolts are considered high-strength parts. They鈥檙e in the neighborhood of SAE J429 Grade 8 parts.

ISO 898-1 Property Class 12.9 Metric Bolt and Screw Head Marking

Finally, here鈥檚 the Property Class 12.9 head marking:

And there鈥檚 nothing surprising about it! Property Class 12.9 bolts and screws have a minimum tensile strength of 1220 MPa for all sizes. 1220 MPa are roughly equivalent to 175 ksi. These parts are very high in strength. In fact, they鈥檙e the strongest of all the fasteners we鈥檝e covered in our inch-series and metric bolt head marking blogs.

Learn More About Metric Bolt and Screw Grades

with 黑料大事记

Interested in learning a bit more about bolt and screw head markings? While this is currently our only blog on metric grades and head markings, we do have a few others you should check out on inch-series parts:

• What Do Screw and Bolt Head Markings Mean?
• Understanding a Few Common ASTM Bolt Grade Markings

And if you have any questions that these blogs can鈥檛 answer for you, feel free to reach out to us. With plenty of experience in the fastener industry, we鈥檒l likely have an answer for you. Give us a call at (800) 656-2658 or contact us online.

The post Understanding Metric Bolt and Screw Grades (and Head Markings) appeared first on 黑料大事记.

In the fastener world, you鈥檒l often hear terms like proof load, yield strength, and tensile strength tossed around when referring to the strength of a given fastener. For those unfamiliar with the precise meanings of these terms, I thought I鈥檇 devote a blog post to help define them and their relation to one another.

Proof load, yield strength, and tensile strength are numbers set by a standard that a fastener must meet in order to qualify as a certain grade or property class. All three numbers are set as minimum (and occasionally maximum) values. For example, according to ASTM A354, in order for a 陆-13 bolt to qualify as grade BD, it must have a minimum proof load of 17,050 pounds-force (lbf), a minimum yield strength of 18,500 lbf, and a minimum tensile strength of 21,300 lbf. Not all standards specify requirements for all three tests. Yield strength and proof load are similar tests, so yield strength requirements are often omitted in favor of proof load requirements, as in SAE J429.

Before I can talk about individual terms, I should talk a bit about the kind of fastener strength involved here. All three terms involve the load that a threaded fastener can hold when pulled perpendicularly from the head. See Figure 1.

In order to test this force, we use the tensile machine in聽our lab.

As you can sort of see, the fastener is fed into the slot in the middle. The machine then exerts a vertical force on the part. The machine measures the force as the part holds, distends, or breaks, depending on the test. To get an idea of how each test works, read on.

What Is Proof Load?

Proof load is an amount of force that a fastener must be able to withstand without permanently deforming. So, to use the example above, in order to pass the proof load test set by ASTM A354, a 陆-13 bolt must be able to hold a load of at least 17,050 lbf for a minimum of ten seconds without permanently elongating. The length of the part is measured before and after the proof load test to ensure compliance.

What Is Yield Strength?

Yield strength is the load that is carried at the point where a fastener permanently deforms. When subjected to enough force, steel will begin to stretch. If the amount of force is low enough, the steel will elastically return to its original shape when the force is removed. At the yield point, the force becomes strong enough that the steel will stretch and not return to its original shape. This amount of force is the yield strength.

To test yield strength in our example, you would put our 陆-13 bolt into the tensile machine, stretch the part until it distends, and calculate the force at the point of yield. In this case, the force would need to be a minimum of 18,500 lbf for the part to pass. The actual process of determining the force at the point of yield is rather engineer-y and involves graphs. If you would like to see it spelled out,聽

What Is Tensile Strength?

A fastener鈥檚 tensile strength, or ultimate tensile strength, is the force at which the fastener fractures. To test tensile strength, we use a wedge tensile test, where a wedge is placed under the head of the fastener, and force is applied until the fastener breaks.

The wedge is used because it puts extra stress on the junction of the head and the body of the fastener. This ensures the absolute integrity of this junction. If the fastener breaks at a force greater than the minimum tensile requirement, the fastener has passed the tensile test. However, the break must not occur at the junction of the head and the body of the fastener. If the break does occur here, the fastener has failed tensile, regardless of the force at which the break occurred.

So to summarize, proof load is a load that can be held without permanent deformation. It is the lowest force of the three forces that we are discussing. Yield strength is the force exerted at which a fastener permanently deforms. Yield strength is a greater force than proof load. Finally, tensile strength is the force at which a fastener will break. It is the strongest of the three forces.

Before I sign off, I would like to point out that when a properly made fastener is subjected to a force greater than its tensile strength, it will break in a cross-section. In other words, the steel itself will give out across the diameter of the fastener before the threads shear. Threads are strong. Threads are cool. We talk about threads in more detail in our three-article series on threads. Part 1 provides a general introduction to threads. Part 2 talks about聽the difference between 2A and 3A threads. Finally, we wrap up with part 3, which聽discusses metric threads.

RELATED: Need a specialty bolt, screw, or stud? 黑料大事记 can help.

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If you poke around a few industrial websites, you鈥檒l begin to notice plenty of references to ISO 9001 certification. If you happen to be an automotive supplier, you may notice a company reference to being 鈥�IATF 16949 certified.鈥� Or, if the company website you鈥檙e perusing has an internal lab, you might see a mention of ISO 17025 conformance.

So what do all these acronyms stand for, and why do all these certifications matter? Below, we鈥檒l discuss the difference between IATF 16949 vs. ISO 9001, as well as their importance in industrial manufacturing. We鈥檒l also mention ISO 17025, since that鈥檚 one that pops up fairly often as well.

IATF 16949 vs. ISO 9001: What鈥檚 the Difference?

IATF 16949 and ISO 9001 are different, but they鈥檙e not mutually exclusive. They sit on top of each other sometimes. Think of it as them having the same structure, but ISO 9001 acts as sort of a foundation.

They were both created by different organizations for different, yet similar purposes. So here are the details on what sets them apart.

ISO 9001:2015 鈥斅燗n Overview

Let鈥檚 start with , as it鈥檚 the most popular and widespread certification across industries. ISO stands for . This is, as its name implies, an international organization that creates and publishes standards.

Interested in learning about ISO standards for fasteners? Check out this blog.聽

ISO 9001 is its quality management standard. It鈥檚 easily the most well-known and accepted quality management standard in the world. The standard itself is a 30 or so-page book that contains requirements for a company鈥檚 quality management system (QMS), which is basically all the policies and procedures put in place by a company to ensure that its products and services meet customer requirements.

The requirements in the ISO 9001 standard cover everything from product planning and development, to customer satisfaction, to everything in between. It鈥檚 meant to provide structure to create a holistic QMS that covers every aspect of quality.

*Note: the 鈥�2015鈥� in ISO 9001:2015 refers to the year that particular revision was released. In this case, 2015 is the most recent revision, replacing the previous version released in 2008. IATF 19649:2016 and ISO 17025:2017 also follow this formula.聽

How Do You Get an ISO 9001:2015 Certification?

By becoming ISO 9001 certified, a company is dedicating itself to follow all the requirements set forth in the ISO 9001 standard. Here鈥檚 what that process looks like:

1. The company structures its QMS, following ISO 9001 guidelines.
2. The company submits to an audit by an accredited third party.
3. The third party auditor performs an on-site audit to verify that the company is following all requirements of the ISO 9001 standard. They note all instances where the company鈥檚 QMS doesn鈥檛 adhere to the standard, and propose corrective actions for non-conformance.
4. Any necessary corrective actions are completed by the company to ensure compliance.
5. The third party auditor issues a certificate of compliance.

Hooray! The company can then claim ISO 9001 certification.

IATF 16949:2016 鈥� An Overview

Next, . IATF, , is an organization of automotive manufacturers and their trade associations. Its purpose is to provide a consistency of QMS requirements for automotive suppliers that can be applied worldwide. Basically, the leading auto companies in the United States and Europe put together a task force that created a quality management standard of their own.

How Do You Get an IATF 16949:2016 Certification?

Any company that supplies parts that are mechanically or electronically attached to a vehicle is eligible to become IATF 16949 certified. An IATF 16949 certification is intended to exist on top of an ISO 9001 certification. Essentially, IATF 16949 is simply a list of extra requirements that automotive suppliers must adhere to over and above the requirements of ISO 9001.

IATF 16949 also required third party certification 鈥斅燼nd, since the IATF 16949 and ISO 9001 certifications are intertwined, most certification bodies will certify both at the same time.

And What About ISO 17025:2017?

ISO 17025 is a bit of a different animal from the previous two standards discussed. Whereas IATF 16949 and ISO 9001 are quality management standards, ISO 17025 is a testing and calibration standard. It鈥檚 designed for laboratories that perform testing, sampling, or calibration. Labs can be either internal (testing only their own products) or external (testing outside clients鈥� parts).

Labs receive ISO 17025 certification for only the tests, sampling, and/or calibration they perform. The accredited tests, sampling, and calibration are listed in the Scope of Accreditation, which is usually attached to the ISO 17025 certificate.

Since it鈥檚 common for an automotive manufacturer to have their own internal lab, it鈥檚 possible and pretty common for the same company to have all three of the certifications we鈥檝e mentioned: IATF 16949, ISO 9001, and ISO 17025.

 

What Are the Benefits of An IATF Certification or An ISO Certification?

IATF certifications and ISO certifications require considerable effort and commitment on the part of the manufacturer. So what鈥檚 the benefit, and why does anyone care about them? The answer is twofold.

First, simply the process of becoming certified to a quality or lab standard adds value to the organization. Having a template to build your QMS or lab upon is helpful, and the process of conforming to the standard most likely requires the company to improve upon current methods. In other words, if you鈥檙e going to put in the work to conform to an international standard, you might as well do it right and use it as an opportunity to improve.

Second, both potential and current customers see IATF certifications and ISO certifications as a shorthand assurance of quality. In fact, many customers will require you to have one of these certifications to do business with you. For example, most automotive original equipment manufacturers (OEMs) require IATF certification for their suppliers, and the Department of Defense requires ISO 9001 certification.

Learn About 黑料大事记鈥檚 IATF and ISO Certifications & Discover Our Commitment to Quality

At 黑料大事记, we hold all of the certifications mentioned in this post: IATF 16949, ISO 9001, and ISO 17025. You can find them on our About Us page.

If you鈥檇 like to learn more about our commitment to quality and how we can deliver the specialty fasteners you need, feel free to reach out online. We鈥檙e happy to walk you through our processes and provide you with effective solutions for your application.

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Hardenability of steel is the ability of the steel to achieve a hardness value at a particular depth beneath the surface.聽(Click here for more information on core hardness and surface hardness in fasteners). The chemical composition of a steel provides the foundation for hardenability. The iron content in steel is around 98%. Carbon (C) is the primary hardening element. Other alloying elements such as manganese (Mn), molybdenum (Mo), chromium (Cr), and nickel (Ni) are often added in small amounts to increase hardenability. The methods of heat treatment, quenching, and tempering of steel develop the material鈥檚 metallurgical structure and mechanical properties, including hardness. A measure of steel鈥檚 hardenability aids fastener engineers in selecting materials that will produce parts with the desired surface and core hardness.

Chemical Composition Among Different Steel Grades

We should begin with some examples of different steel grades and their chemical composition, just to give an idea of the different compositions of different grades. We鈥檒l use three grades that we at 黑料大事记 use frequently: 1541, 4037, and 4140. The chemical composition numbers below were taken directly from the steel certifications provided by our steel supplier. See Figure 1.

Hardenability Testing

As stated above, different chemical composition has an effect on hardenability. In order to quantify the differences in hardenability, engineers developed a standard reference test for hardenability, the Jominy end quench test per聽. This test provides data for the changes in hardness along the length of a 1鈥� diameter x 4鈥� long round test bar. The test is run as follows: A test bar is heated to 1600 degrees F, then quickly hung vertically in a fixture. The lower end is quenched using a room temperature water spray. After cooling, a narrow flat is ground along the surface of the 4鈥� length. Rockwell C hardness measurements are made on the flat surface at 1/16鈥� distance increments from the quenched end. The hardness results at each distance location are plotted on a graph, creating what is commonly called a Hardenability Curve.

RELATED: Need a specialty bolt, screw, or stud? 黑料大事记 can help.

Hardenability Curves

Figure 2 below shows Hardenability Curve results for three grades of steel, 1541, 4037, and 4140, using Jominy test data provided by our steel suppliers with their shipment to our company. The material at the quenched end has the fastest cooling rate and the highest hardness. Moving away from the quenched end, the cooling rate slows, and the hardness decreases. As you can clearly see from the two figures, different chemical compositions can have a major effect on the hardenability of different grades.

Steel Grade Numbering

Before we conclude, let鈥檚 take a look at the AISI/SAE nomenclature for carbon and alloy steel grade chemical compositions. The designation system consists of four numbers (XXXX). The left two digits represent the type of material, beginning with 10 (plain carbon steel) and progressing up through many alloy combinations to 98 (nickel-chromium-molybdenum steel). . The right two digits represent the amount of carbon (C) in the material, expressed as a percentage by weight. This is a nominal percentage, meaning that specifications allow a range of carbon content.

Here鈥檚 an example: Grade 1038
Material Type 鈥� 10XX 鈥� Non-modified plain carbon steel.
Carbon content 鈥� XX38 鈥� SAE carbon specification range is 0.35% minimum to 0.42% maximum (the nominal value 38 just splits the difference between the high and low limits).

Here鈥檚 another example: Grade 8640
Material Type 鈥� 86XX 鈥� Nickel-Chromium-Molybdenum Steel
Carbon Content 鈥� XX40 鈥� SAE carbon specification range is 0.38% minimum to 0.43% maximum.

And with that, we鈥檝e come to the end of our discussion on hardenability. If you would like to learn more about hardenability for carbon and alloy steel grades, we recommend聽聽as a good reference. And click聽here for a primer on core and surface hardness in fasteners.

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