Earnest Machine Newsroom

Understanding Zinc Trivalent Finishes

Fri, 17 Jul 2026 12:00:00 Z

If you've ever worked with threaded fasteners, you've likely encountered finishes such as Zinc Clear Trivalent, Zinc Black Trivalent, and Zinc Yellow Trivalent. Because they have different appearances, it's easy to assume they're completely different finishes.

They're not.

Every zinc trivalent finish is created using the same basic process. It begins by thoroughly cleaning the steel fastener to remove oils, dirt, and other surface contaminants left behind during the manufacturing process that could interfere with plating. Once cleaned, the fastener is submerged in a zinc electroplating bath, where an electrical current deposits a thin, uniform layer of metallic zinc onto the surface of the steel, giving the fastener the bright silver appearance commonly associated with zinc plating.

The basic zinc electroplating process is illustrated below.

After the electroplating process is complete, the fastener is placed in a trivalent chromate solution. The trivalent chromate reacts with only the outermost surface of the metallic zinc, transforming the surface into a thin protective film. This is known as a conversion coating, which helps protect the zinc while giving the finish its final appearance. After the conversion coating has formed, the fastener is then rinsed to remove any remaining solution and allowed to fully cure before the finished part is ready for use.

The trivalent chromate conversion process is illustrated below.

Together, the zinc plating and the conversion coating work in layers. The conversion coating helps slow corrosion of the zinc beneath it, while the zinc protects the underlying steel by acting as a sacrificial metal. This means the zinc is designed to corrode before the steel does. This layered approach is what makes zinc trivalent finishes one of the fastener industry's most widely used protective finishes.

Why Are Zinc Trivalent Finishes Available in Different Colors?

The color of a zinc trivalent finish is determined by the chemistry of the trivalent chromate solution used during the conversion coating process. Because different trivalent chromate solutions use different chemistries, they produce conversion coatings with different appearances. A clear trivalent chromate solution forms a nearly transparent film that preserves the bright silver appearance of the zinc plating, while black, yellow, and olive drab trivalent chromate solutions produce films with their respective colors. Examples of Zinc Clear Trivalent, Zinc Black Trivalent, Zinc Yellow Trivalent, and Zinc Olive Drab Trivalent finishes are shown below.

Does the Color Affect Corrosion Performance?

One of the most common misconceptions about zinc trivalent finishes is that the color determines corrosion resistance.

It does not.

A Zinc Clear Trivalent finish is not automatically less corrosion resistant than a Zinc Black Trivalent finish, and a Zinc Yellow Trivalent finish does not automatically provide more protection than either. The color of a zinc trivalent finish also has no relationship to the fastener's grade or mechanical properties.

Color is simply one characteristic of the specified finish. Corrosion resistance is determined by the finish requirements identified in in any relevant product documentation, not by the color of the conversion coating. Likewise, a fastener's grade is determined by the material and mechanical property requirements defined by the applicable industry standard, not by the finish applied.

How Zinc Trivalent Finishes Compare to Zinc Flake Coatings

Because both zinc trivalent finishes and zinc flake coatings help protect steel from corrosion, they are sometimes confused with each other. However, they are created using different processes.

As mentioned earlier, zinc trivalent finishes begin with electroplating, followed by a trivalent chromate.

Zinc flake coatings, on the other hand, are non-electrolytically applied coatings. Rather than depositing zinc onto the fastener through electroplating, zinc flake coatings use a completely different manufacturing process to apply a zinc-rich coating to the surface of a fastener.

If you'd like to learn more about zinc flake coatings, be sure to read our companion piece, What Are Zinc Flake Coatings and Why Are They Important?

Putting It All Together

Although Zinc Clear Trivalent, Zinc Black Trivalent, Zinc Yellow Trivalent, and Zinc Olive Drab Trivalent each have different appearances, they all begin with the same electroplating process. The trivalent chromate applied afterward is what gives each finish its unique appearance while helping protect the zinc beneath it.

Whether you're purchasing, specifying, sourcing, or simply learning about fasteners, understanding how zinc trivalent finishes are created and why they look different will help you communicate more confidently with customers, suppliers, and coworkers.

If you have questions about zinc trivalent finishes or any of the fasteners we supply, contact Earnest Machine at 800-327-6378 or inquiry@earnestmachine.com. We're always happy to help.

A Better Way to Write Fastener Part Descriptions

Wed, 24 Jun 2026 12:00:00 Z

In the fastener industry, there is no universally accepted standard for writing part descriptions.

That might sound surprising, but that's the reality. Two companies can describe the exact same product in completely different ways. Information may be presented in a different order, placed outside of the description altogether, or abbreviated in ways that are not universally understood.

At Earnest Machine, we believe there is a better way.

A part description should clearly communicate exactly what product is being bought, sold, quoted, or sourced. Whether it's a customer, salesperson, buyer, or warehouse team member, the information in the description should be easy to read, easy to understand, and easy to interpret.

Most importantly, it should eliminate any guesswork.

While no official industry standard exists, Earnest Machine has established a standardized approach to writing fastener part descriptions. As part of our ongoing commitment to product data quality and information management, we believe our approach is the clearest, most scalable, and most useful way to communicate fastener information.

The foundation of our approach is consistency. We organize information in a logical order and minimize the use of abbreviations whenever possible. We start with dimensional data and then include any additional product characteristics needed to clearly identify the fastener, such as the material specification, grade or class, product name, whether the fastener is full or partially threaded (this primarily applies to externally threaded fasteners), and finish. Every element serves a purpose, and every description follows the same logical order, helping ensure product information is clear and easy to understand.

To see what that looks like in practice, let's take a look at the example below:

Let's break down each component of the description.

The first section, 1/4-20x1 1/8, is the dimensional data. It identifies the diameter, thread pitch, and length of the fastener. In this example, 1/4 is the nominal diameter, 20 is the number of threads per inch, and 1 1/8 is the length. This information comes first because size is usually the first thing someone needs to identify.

Next is SAE J429, which identifies the material property specification. This information helps establish the mechanical properties associated with the fastener and provides additional insight into the performance expectations of the part.

Grade 8 identifies the strength level of the fastener. This is important because two fasteners of the same size and style may have very different strength characteristics. Without specifying the grade, it can be difficult to understand the performance capabilities of the fastener.

Hex Head Cap Screw identifies the product itself. At Earnest Machine, we spell out product names instead of using abbreviations. Abbreviations may save space, but they can also create uncertainty. A clear description should be written so that anyone can understand it without needing to decode it.

Full Thread identifies how much of the fastener is threaded. This matters because some externally threaded fasteners are fully threaded while others are partially threaded.

Finally, Plain Finish identifies the plating or coating applied to the product. Finish can affect appearance, corrosion resistance , and the environments in which the fastener is intended to be used.

The value of this approach isn't found in any single attribute. It's found in the structure itself. By presenting information in a consistent order, minimizing abbreviations, and including critical product details directly within the description, Earnest Machine has established a format that provides a complete view of the product within a single description.

As shown below, the same product may be represented differently across the fastener industry. While there are many ways to write a part description, we believe our standardized format provides the clearest and most consistent way to communicate important product information.

The same philosophy applies to metric fasteners. While the standards and dimensional conventions change, the structure remains consistent.

Although these examples focus on externally threaded fasteners, the same approach extends across Earnest Machine's entire product offering. The specific attributes may change from product to product, but the goal remains the same. A description should communicate the most important information in an order that is clear, consistent, and scalable across a large product catalog.

This is especially important in an industry where products are bought, sold, quoted, sourced, inspected, stocked, and shipped by different people throughout the supply chain. Everyone involved should be able to look at a part description and understand exactly what product is being referenced.

There may not be an official industry standard for fastener part descriptions, but we believe there is a best practice. Include the critical information, present it in a consistent order, spell it out clearly, and eliminate the guesswork. That's the standard we've established at Earnest Machine, and we believe it's the best path forward for the industry.

Grade A and Grade 2 Fasteners: Similar, But Not the Same

Tue, 16 Jun 2026 12:00:00 Z

In the fastener industry, Grade A and Grade 2 fasteners are often thought to be equivalent in terms of strength. While these low-strength carbon steel fasteners share many characteristics and are commonly used in similar general-purpose applications, they are defined by different ASTM and SAE standards.

Because Grade A and Grade 2 classifications appear in multiple standards, their mechanical property requirements, including tensile strength, proof load, hardness, and yield strength, can vary depending on the fastener type. Examples include:

ASTM A307 Grade A specifies carbon steel bolts, studs, and threaded rod
SAE J429 Grade 2 specifies externally threaded fasteners, including bolts and cap screws
ASTM A563 Grade A specifies carbon steel nuts
SAE J995 Grade 2 specifies carbon steel nuts

Although these standards use similar grade designations, they do not define the same products. As a result, Grade A and Grade 2 should not be viewed as universal fastener grades or assumed to be directly interchangeable within an assembly.

Among these specifications, ASTM A307 Grade A and SAE J429 Grade 2 are two of the most commonly compared bolt grades. While both are used in general-purpose fastening applications, their mechanical properties are not the same. One example is their minimum tensile strength, shown in the table below.

The comparison highlights an important point. Grade designations only have meaning within the standards that define them. Even when two grades are commonly associated with one another, they may not have the same mechanical properties.

The specified standard and grade can also affect documentation, certifications, and traceability requirements. When a customer requests ASTM A307 Grade A, supplying an SAE J429 Grade 2 fastener instead means supplying a different standard and grade than what was originally requested.

In many general-purpose applications, the differences between these grades may not have a significant impact on performance, and some suppliers or customers may be comfortable using either grade. However, that shouldn't be assumed. Before supplying a different standard or grade, it's important to verify that your customer understands the difference and approves the substitution.

The key takeaway is simple. Grade A and Grade 2 are not universal fastener grades. Their meaning depends on the ASTM or SAE standard in which they appear. Understanding that distinction can help prevent sourcing mistakes and reduce confusion when specifying, purchasing, or supplying fasteners.

At Earnest Machine, we stock a wide range of industrial fasteners in a variety of grades, materials, finishes, and industry specifications. Whether you need help locating a specific fastener or sourcing a hard-to-find item, our team is ready to help. Contact Earnest Machine at 800-327-6378 or inquiry@earnestmachine.com

Prevailing Torque vs. All-Metal Lock Nuts

Fri, 22 May 2026 15:27:51 Z

In the fastener industry, the terms prevailing torque lock nut and all-metal lock nut are often used interchangeably. While they’re closely related, they are not exactly the same thing. Understanding the difference can help avoid confusion when reviewing specifications, sourcing parts, or selecting the right fastener for an application.

At the most basic level, a prevailing torque lock nut is any lock nut designed to resist loosening by creating friction between the nut and bolt threads before the nut is fully tightened. The resistance created during installation is known as prevailing torque. This added friction helps the assembly maintain clamp load and resist loosening caused by vibration or movement.

An all-metal lock nut, on the other hand, refers specifically to the construction of the nut itself. As the name suggests, all-metal lock nuts contain no nylon or non-metallic inserts. Instead, the locking action is created by intentionally distorting or crimping a portion of the nut near the top threads. As the bolt is tightened into the nut, the distorted portion creates resistance during installation, generating the prevailing torque that helps prevent the fastener assembly from loosening due to vibration or movement.

Most all-metal lock nuts are considered prevailing torque lock nuts because their design creates resistance during installation. However, not all prevailing torque lock nuts are all-metal. Nylon insert lock nuts also create prevailing torque through friction generated by the nylon insert. The locking method is different, but the functional principle is the same.

In simple terms:

Prevailing torque describes how the nut locks
All-metal describes what the nut is made of

That distinction matters because material construction directly affects where the fastener can be used.

All-metal lock nuts are commonly selected for high-temperature or demanding industrial environments where a nylon insert lock nut might exceed its temperature rating. Applications involving heat, chemicals, or heavy vibration often favor all-metal designs because they maintain locking performance without relying on non-metallic components.

Common applications for all-metal lock nuts include:

Heavy equipment
Automotive applications
Industrial machinery
Structural assemblies
Exhaust and high-heat environments

Nylon insert lock nuts remain widely used across many industries because they are cost-effective, reusable in some applications, and provide reliable vibration resistance in moderate environments. However, because the nylon insert is temperature rated, these lock nuts may not be recommended for high-heat applications or environments involving certain chemicals.

When reviewing fastener specifications, it’s important not to assume the two terms mean exactly the same thing. A specification calling for a prevailing torque lock nut may allow either a nylon insert or an all-metal design depending on the application requirements. If temperature resistance, durability, or material compatibility are critical, confirming the exact lock nut style becomes especially important.

Understanding the difference between prevailing torque lock nuts and all-metal lock nuts can help buyers and sourcing teams select the right fastener for the application. Earnest Machine stocks a wide range of industrial fasteners, including serval different types of all-metal and nylon insert lock nuts. Whether you need help locating a specific fastener or sourcing a hard-to-find item, our team is ready to help. Contact Earnest Machine at 800-327-6378 or inquiry@earnestmachine.com.

Coarse vs. Fine Threads: What’s the Difference?

Thu, 07 May 2026 12:00:00 Z

When working with threaded fasteners, understanding the difference between coarse and fine threads is important, especially when comparing parts or reviewing customer specifications.

At a basic level, it comes down to threads per inch (TPI).

Coarse threads have fewer threads per inch, which means the threads are larger and spaced farther apart. Fine threads have more threads per inch, so the threads are smaller and more closely spaced. Put them side by side and the difference is easy to see, as shown below.

Coarse threads have a deeper, more pronounced profile, while fine threads create more points of contact along the same length of the fastener. This means more thread surfaces are engaged as the fastener is tightened, which can provide better load distribution and improved holding strength in certain applications.

Because of their larger profile, coarse threads tend to be more forgiving in real-world conditions. The wider spacing leaves more room for coatings, dirt, light corrosion, or metal chips without interfering with assembly. If there’s slight damage to the threads, the wider spacing gives the fastener a better chance of still fitting together properly.

Coarse threads are also typically faster to install and assemble because the wider spacing allows the fastener to advance more quickly with each turn. This makes them a practical choice for applications where speed and ease of assembly are important.

Fine threads, on the other hand, are tighter and more closely spaced. Because of the tighter spacing, there’s less room for variation. The tradeoff is that coatings, debris, or minor damage are more likely to affect thread engagement.

However, the tighter spacing that fine threads offer can provide several advantages depending on the application. Fine threads are often used where more precise adjustment is needed, where stronger clamping force is beneficial, or where resistance to loosening from vibration is important. The additional engaged threads can also help distribute loads more evenly across the fastener.

In simple terms:

• Coarse threads = fewer, larger, more widely spaced threads with faster assembly
• Fine threads = smaller, more closely spaced threads with better adjustment control and resistance to loosening

Understanding these differences makes it easier to compare parts and avoid mismatches when sourcing or ordering fasteners.

If you have questions about thread types or customer specifications, Earnest Machine can help. Contact our sales team at 800-327-6378 or email inquiry@earnestmachine.com to make sure you’re sourcing exactly what you need.

What Is a Castle Nut & Why Is It Used?

Wed, 11 Feb 2026 16:18:32 Z

Castle nuts are used in assemblies where movement, vibration, or changing loads could cause a fastener to loosen over time. Instead of relying solely on torque to maintain clamping force, a castle nut uses a physical locking method to prevent rotation after installation.

You will commonly see castle nuts in applications where reliability matters and failure is not an option, such as in steering systems, suspension components, and aircraft assemblies.

What Makes a Castle Nut Different?

A castle nut, also called a castellated nut, looks similar to a standard hex nut but includes a short cylindrical collar above the hex body, with evenly spaced slots cut into it, as illustrated below. These slots are designed to accept a cotter pin after the nut is tightened.

Castle nuts are also designed to be used with bolts that have been cross-drilled. Once the nut is threaded onto the bolt, a cotter pin is inserted through one of the slots in the collar and through the hole in the bolt. The cotter pin is then bent around the nut to secure it in place. Once installed, the cotter pin physically blocks the nut from rotating, allowing it to maintain proper clamping force while remaining locked in position.

Castle Nut vs. Slotted Hex Nut: What’s the Difference?

Castle nuts are often confused with slotted hex nuts, and while they look similar, they are not the same.

A castle nut has slots cut into a raised collar above the hex. This extra height gives more flexibility when aligning the slots with a drilled hole and helps maintain full thread engagement.

However, a slotted hex nut has slots cut directly into the body of the hex nut itself, with no raised collar. Because there is less material above the threads, alignment options can be more limited, and thread engagement can be reduced depending on the application. Both styles are shown below for comparison.

Each style uses cotter pins to prevent rotation, but castle nuts are generally preferred in higher-load or safety-critical assemblies where strength and long-term reliability are important. For this reason, they are not always interchangeable, even if the thread size matches.

When Is a Castle Nut the Better Choice?

Castle nuts and slotted hex nuts both rely on cotter pins to prevent rotation, but the differences in their design can affect strength, alignment, and long-term performance.

A castle nut is often the better choice in assemblies exposed to excessive vibration, movement, or changing loads. The raised collar makes it easier to align the nut with a cross-drilled hole without backing it off after tightening. This helps maintain full thread engagement and consistent clamping force in critical joints.

Slotted hex nuts may be suitable for lower-load applications or situations where overall height is limited. Because the slots are cut directly into the hex body, there are fewer positions where a slot can line up with a cross-drilled hole, which can limit how the nut is tightened and secured.

Choosing between a castle nut and a slotted hex nut depends on the demands of the application, including load, vibration, and installation requirements. Earnest Machine supplies both castle nuts and slotted hex nuts in a wide range of sizes, grades, and finishes, supported by exceptional customer service and consistent delivery. For pricing or availability, contact our team today at 800-327-6378 or email inquiry@earnestmachine.com.

Stainless Steel Fastener Grades Explained

Tue, 27 Jan 2026 12:00:00 Z

The term stainless steel is often used as if it describes a single, uniform material, but it actually refers to a range of alloys available in multiple grades with different chemical compositions and performance characteristics. When selecting stainless steel fasteners, it’s important to remember that the grade directly affects corrosion resistance and overall performance in the assembly.

At Earnest, we typically supply 18/8 stainless steel, often referred to as Grade 18/8 or Grade 304, along with Grade 316 and metric fasteners designated as Class A2 or Class A4.

But What Exactly Does “18/8” Stainless Steel Mean?

The term 18/8 refers to a stainless steel composition containing approximately 18% chromium and 8% nickel. These elements are what give stainless steel its corrosion resistance and durability.

Strictly speaking, 18/8 is not a formal grade designation. It describes a chemical composition range rather than a specific alloy defined by a published material standard. In fastener specifications, however, 18/8 is commonly treated and understood as a grade across the industry. In other words, 18/8 defines the stainless steel’s chemistry rather than a single standardized alloy designation.

In practice, most fasteners sold as 18/8 are manufactured from Grade 304 stainless steel or a closely related alloy that falls within the same composition range.

How 18/8 Relates to Grade 304 Stainless Steel

Grade 304 is the most common stainless steel alloy used for fasteners and is defined by ASTM material specifications. It falls within the 18/8 composition range and provides good corrosion resistance across a wide range of indoor and outdoor environments.

Grade 304 performs well in applications where fasteners may be exposed to moisture, humidity, or mild chemicals, but not aggressive chlorides or saltwater. It is frequently used in general manufacturing, enclosures, food equipment, and structural assemblies.

Because machining and forming processes can leave free iron particles on the surface of the alloy, Grade 304 fasteners are often passivated to improve corrosion resistance and long-term performance in the assembly.

When Grade 316 Is the Better Choice

Grade 316 is a stainless steel alloy similar to Grade 304 but with added molybdenum, which improves resistance to chlorides and more aggressive corrosive environments. Like Grade 304, it is defined by ASTM material specifications.

Grade 316 is widely used in marine, coastal, and chemical processing applications where exposure to salt or chemicals would exceed the corrosion resistance of Grade 304. It is typically chosen when long-term durability and corrosion resistance are required.

As with other stainless steel grades, proper surface treatment such as passivation can help promote consistent corrosion resistance and reliable performance in demanding environments.

Understanding Metric Classes A2 and A4

In metric systems, stainless steel fasteners are commonly specified by property class rather than alloy number.

Class A2 fasteners are generally equivalent to Grade 304 stainless steel and offer similar corrosion resistance. They are suitable for most general-purpose applications where environmental exposure is moderate.

Class A4 fasteners are typically manufactured from 316 stainless steel. This alloy includes molybdenum, which improves resistance to chlorides and harsh environments. A4 fasteners are commonly used in marine applications, coastal installations, and chemical processing environments where corrosion risk is higher.

Choosing the Right Stainless Steel Grade for Your Application

Selecting the right stainless steel grade depends on the operating environment, expected exposure, and service life requirements.

Grade 18/8, Grade 304, or Class A2 fasteners are often suitable for indoor use and many outdoor applications where salt exposure is limited. Grade 316 and Class A4 fasteners are better suited for marine, coastal, or chemically aggressive environments.

While higher-alloy grades offer increased corrosion resistance, they often come at a higher cost and are generally used only when the application demands that added performance. Understanding the differences between grades helps ensure the correct material is supplied, even when application details are limited.

How Grade and Surface Treatment Work Together

Stainless steel relies on a thin passive oxide layer to resist corrosion, but manufacturing processes such as machining or cold forming can disrupt this layer and leave surface contaminants behind.

As discussed in our previous article, Understanding Passivation in Stainless Steel Fasteners, passivation helps remove free iron particles from the surface of the fastener and restores the protective chromium oxide layer. This process improves corrosion resistance and performance consistency across all stainless steel grades.

Choosing the right grade is important but pairing that material with proper surface treatment is often what ensures long-term fastener reliability.

Understanding Passivation in Stainless Steel Fasteners

Tue, 21 Oct 2025 12:00:00 Z

Stainless steel fasteners are valued for their high strength, durability, and exceptional resistance to corrosion. They’re used across a wide range of industries and can be found in electronics, food processing equipment, medical devices, home appliances, and large-scale construction equipment.

Although stainless steel is often considered a maintenance-free material, certain manufacturing processes can weaken its surface protection. During forming, machining, or handling, microscopic contaminants and imperfections can leave the material vulnerable to oxidation. To maintain the material’s protective surface, stainless steel must undergo a finishing process called passivation, a chemical treatment that restores and strengthens the metal’s natural corrosion barrier.

Passivation is an important part of protecting stainless steel, but to understand why it’s necessary, it helps to first look at how the material itself is made and how its protective surface layer naturally forms.

How Stainless-Steel Alloys Are Made

Stainless steel is made primarily from iron and chromium, often with additional elements such as nickel and molybdenum depending on the grade and application. The chromium content, at least 10.5% by mass, is what gives stainless steel its inherent ability to resist rust.

In production, these elements are melted together in industrial furnaces, refined, and cast into the desired form. When the solidified alloy is exposed to oxygen, the chromium at the surface reacts with it to form a thin, invisible layer of chromium oxide. This passive film acts as a stable, self-healing barrier that prevents rust from forming on the steel underneath. This naturally formed layer is also responsible for stainless steel’s recognizable, bright finish, giving it a smooth and reflective appearance.

While stainless steel’s chromium oxide film provides strong corrosion resistance, it can be compromised during manufacturing. When that happens, the material needs help restoring its full protective qualities. That’s where passivation comes in.

Passivation Explained

It’s important to note that passivation isn’t a coating or an applied finish. It’s a chemical process that removes surface contaminants and reinforces stainless steel’s natural ability to resist corrosion.

As mentioned earlier, stainless steel can pick up trace amounts of iron from cutting tools or other equipment. These tiny surface deposits don’t bond with the alloy and are more prone to rusting. This contamination is known as free iron. If left on the surface, free iron can oxidize when exposed to moisture, creating rust that spreads and weakens the surrounding material.

Passivation removes these contaminants and restores the stainless-steel surface to its clean, corrosion-resistant state. Here’s how it works in practice:

Cleaning: Fasteners are thoroughly cleaned using an alkaline detergent or solvent cleaner to remove machining oils, lubricants, and other residues left from manufacturing. In some cases, parts may also be rinsed with water or ultrasonically cleaned to ensure the surface is completely free of contaminants before passivation begins.
Acid Bath: The fasteners are immersed in a nitric or citric acid solution. The acid selectively dissolves and removes free iron and other contaminants while leaving the stainless steel itself untouched.
Oxide Layer Enhancement: With the surface clean and free of impurities, the acid bath promotes the rapid formation of a fresh chromium oxide layer. The result is a uniform, stable, and dense film that enhances the material’s corrosion resistance.

After treatment, the fasteners are thoroughly rinsed with deionized or distilled water to remove any remaining acid and contaminants. They’re then dried in a clean environment, typically using warm air or controlled heat, to prevent water spots or surface oxidation. The result is a stainless-steel fastener with a clean, passive surface and optimized corrosion resistance. You can’t see the effects of passivation, but they make all the difference in performance and longevity.

Why Passivation Matters

Passivation might be one of the final steps in manufacturing stainless steel fasteners, but it’s also one of the most important. By removing surface contaminants and restoring the protective chromium oxide layer, passivation ensures stainless steel delivers the corrosion resistance it’s designed for. It’s what keeps fasteners from seizing, staining, or failing prematurely in service, protecting both the product and the assemblies they hold together.

At Earnest Machine, we understand how manufacturing details impact the fasteners you depend on. We’re here to help you source quality products efficiently and keep your business moving forward. For questions about product availability or support, contact us at 800-327-6378 or email inquiry@earnestmachine.com.

How Earnest Machine Serves the MRO Market: Fasteners, Fulfillment & Unmatched Reliability

Mon, 20 Oct 2025 12:00:00 Z

Maintenance, Repair, and Operations (MRO) professionals know that downtime is expensive and reliability is everything. When a machine breaks or a facility needs fast turnaround, there's no time to wait on parts, chase unreliable vendors, or worry about inaccurate shipments. That’s where Earnest Machine comes in.

As a trusted industrial fastener distributor, Earnest Machine has built a reputation on being more than just a supplier—we’re a partner to MRO teams across North America. From extensive in-stock inventory to custom labeling and kitting services, we specialize in helping MRO companies keep operations running smoothly, efficiently, and on budget.

Industrial Fasteners You Can Count On
Earnest Machine stocks a broad range of high-quality industrial fasteners including bolts, nuts, washers, screws, and specialty items in both inch and metric sizes. Our inventory includes fasteners made to meet or exceed key specifications such as ASTM, SAE, and DIN standards, ensuring safety and performance in demanding environments.
We maintain deep stock levels of commonly used fasteners, so when you need something quickly, there’s a high chance we already have it ready to ship.

Fast Shipping & Nationwide Distribution
MRO success often comes down to speed. With strategically located distribution centers across the U.S., we can ship same-day or next-day to most industrial markets. Whether you're facing a routine order or an emergency fix, our fulfillment team is trained to deliver with urgency and accuracy.

Earnest also offers blind drop shipping, custom packing slips, and freight optimization services—ensuring fasteners arrive where you want, how you want.

Problem Solvers, Not Just Order Takers
We’re known for going above and beyond. Earnest Machine offers technical support, product sourcing, and application expertise to help solve your toughest challenges. We're built to support both daily MRO operations and long-term procurement strategies.

Why MRO Companies Choose Earnest Machine
✅ Deep fastener inventory with industrial-grade quality
✅ Fast, accurate shipping from multiple U.S. locations
✅ EDI, inventory, and purchasing system integration
✅ Custom packing, kitting, and labeling
✅ Hands-on service from real people who know fasteners

Let’s Keep You Running
If you’re an MRO buyer, planner, or maintenance professional searching for a reliable fastener distributor, Earnest Machine is ready to support your mission. Let us help you reduce downtime, simplify sourcing, and gain peace of mind knowing your fasteners are handled by experts.

What Are Zinc Flake Coatings and Why Are They Important?

Wed, 27 Aug 2025 13:44:13 Z

When fasteners are exposed to corrosive environments, the type of finish applied to their base material plays a major role in determining how long they last and how well they perform in their intended application. Whether in automotive manufacturing, marine environments, or heavy equipment, the right finish is essential to preventing corrosion and maintaining long-term performance.

Among the wide variety of finishes used across the fastener industry, zinc flake coatings continue to stand out for their proven performance and corrosion resistance. They're especially valued in applications where traditional electroplated finishes fall short, particularly when used on high-strength steel fasteners that require corrosion protection without the risk of hydrogen embrittlement.

As durability expectations rise across multiple industries, zinc flake coatings offer a reliable solution for protecting fasteners in some of the most demanding environments. But what exactly is a zinc flake coating, and what makes this finish so effective at resisting corrosion?

Zinc Flake Coatings Explained

Zinc flake coatings are non-electrolytic finishes made by suspending zinc and aluminum flakes in a binder. The binder works like an adhesive, holding the metal flakes together and helping them bond to the fastener during application. Once cured, it forms a hard, protective film. Most binders are resins made from either carbon-based materials like synthetic polymers or mineral-based compounds like silicates, depending on the coating’s performance requirements.

The coating is applied using methods such as a dip-spin process, where fasteners are submerged in the coating solution and spun out to remove excess material, or a spray application that evenly covers the surface before curing. Both methods create a thin, uniform layer that protects the fastener without altering its dimensions.

Additionally, because no electricity is involved in either process, zinc flake coatings completely avoid the risk of hydrogen embrittlement. This is a critical advantage for high-strength fasteners like Grade 8, Class 10.9, or Class 12.9, which are more prone to failure if hydrogen becomes trapped in the steel during traditional electroplating.

How Zinc Flake Coatings Resist Corrosion

Zinc flake coatings protect fasteners in two main ways. The first is by barrier protection, where the overlapping zinc and aluminum flakes form a defensive shield that blocks moisture, salts, and chemicals from reaching the steel surface. The second is sacrificial protection, where the zinc corrodes first instead of the steel if the coating is damaged or corrosion begins. This self-sacrificing action slows rust from developing and helps keep the steel intact for a longer period.

While traditional zinc electroplating also provides these protections, zinc flake does it more effectively by creating a denser barrier, offering more zinc for longer-lasting sacrificial protection, while avoiding the risk of hydrogen embrittlement. This dual protection, combined with a thin, uniform finish that preserves thread fit, gives zinc flake coatings their exceptional corrosion resistance.

With these performance advantages, it is easy to see why zinc flake coatings are used across many industries today. However, on spec sheets, drawings, customer prints, or other technical documents, you may not always see the term “zinc flake” called out. Instead, the coating may be referenced by a brand name.

Common Zinc Flake Coating Brand Names

Zinc flake coatings are often sold under several brand names. Depending on the supplier or OEM, you might see them specified as:

• Geomet®
• Magni®
• Delta Protekt®
• Zintek®
• Dacromet® (less common today due to hexavalent chromium content)

While each brand uses its own formulation and application process, all are zinc flake coatings that provide the same fundamental benefits, such as long-lasting corrosion protection, uniform coverage, and no risk of hydrogen embrittlement.

Why They Matter

Zinc flake coatings matter because they solve several challenges that other finishes cannot. They provide strong corrosion resistance while avoiding hydrogen embrittlement, which makes them especially well-suited for high-strength fasteners. At the same time, their thin, uniform coating preserves thread fit so parts fit together as intended, without the concern of thread interference from an excessive coating thickness. These qualities make zinc flake coatings a dependable finish for fasteners used in demanding environments like in automotive, marine, and heavy equipment applications.

For anyone reading prints, drawings, or specifications, knowing that zinc flake coatings can appear under different brand names is equally important. Recognizing these coatings, regardless of how they are called out, helps avoid confusion or costly mistakes and ensures the correct parts are sourced right the first time.

How Earnest Helps

At Earnest Machine, we know customer prints and specifications aren’t always clear about what finish is required. Some may list a brand name, others a performance requirement, and some leave room for interpretation. Our team has the knowledge to sort through these details, match the right coating or equivalent, and make sure the fasteners you source meet your customer’s needs. If you have a question or need support, call us at 800-327-6378 or email inquiry@earnestmachine.com.

How Earnest Machine Supports the Mom-and-Pop Market: Fasteners, Speed & Service You Can Trust

Wed, 27 Aug 2025 12:00:00 Z

Running a small business is no small task. For Mom-and-Pop shops, every customer order, every deadline, and every repair matters. There’s no room for slow shipping, out-of-stock parts, or unreliable suppliers—especially when your name is on the line.

That’s why Earnest Machine is proud to be a trusted partner for small, independent businesses across North America. Whether you need one box or a truckload of fasteners, we’re here to make sure you get the parts you need, when you need them, without the headaches.

Fasteners for Every Need
From a single box of bolts to specialty hardware for a custom project, Earnest Machine carries an extensive range of industrial fasteners including:

• Bolts, nuts, washers, and screws
• Metric and imperial sizes
• Standard and specialty grades
• Coated and plated finishes for corrosion resistance
• Hard-to-find and discontinued items

If you can’t find it in our stock, we’ll work to source it or manufacture it to print—whether it’s a large-volume order or a short-run special.

Same-Day Shipping for Small Businesses

We know that when your operation stops, your revenue stops. That’s why we offer same-day shipping on in-stock items from our strategically located U.S. warehouses.

Our fast, accurate fulfillment means your order goes out the door right away, helping you keep jobs moving and customers happy.

Per-Print Specials: Large Runs or Small Batches
Sometimes, you need something unique. Whether it’s a high-volume production run or a short batch of custom fasteners, Earnest Machine offers per-print specials to meet your exact specifications.

We handle custom dimensions, materials, coatings, and threading, ensuring you get precisely what your project requires.

24/7 Web Service for Ordering Anytime
Your workday doesn’t always end at 5 PM—and neither should your supplier’s accessibility. Earnest Machine’s 24/7 web ordering system lets you:

• Search our inventory anytime
• Place orders after hours or on weekends
• View order history and shipping details
• Check stock levels in real-time

Whether it’s early in the morning or late at night, we’re ready when you are.

Services That Go Beyond the Box
We don’t just ship fasteners—we help make your job easier with services like:

• Custom labeling with your part numbers
• Kitting for jobs and assemblies
• Blind drop shipping directly to your customers
• Lot traceability and material certifications
• Flexible pack quantities to fit your needs

These extra touches save you time, reduce mistakes, and help you deliver better service to your customers.

Why Mom-and-Pop Shops Choose Earnest Machine
✅ Reliable same-day shipping
✅ Wide range of in-stock fasteners
✅ Custom per-print specials for unique needs
✅ 24/7 online ordering and account access
✅ Friendly, knowledgeable customer service
✅ Support for both large and small orders

Your Fastener Partner for the Long Haul
At Earnest Machine, we understand that small businesses need big reliability. We’re here to keep your shelves stocked, your projects moving, and your customers coming back.

Whether you’re repairing equipment, filling a customer order, or starting a custom build, you can count on us for the right fasteners—right when you need them.

What Does It Mean When a Fastener Is Case Hardened?

Mon, 04 Aug 2025 12:00:00 Z

In fastener manufacturing, heat treatments play a major role in determining how a part performs in the field. These processes are often used to manipulate the hardness level, strength level, and ductility of a fastener, depending on the requirements of the application or the end user.

One common and cost-effective method for increasing a fasteners durability is called case hardening. This process increases a fastener’s surface durability while preserving its elasticity.

But what exactly does that mean?

Case hardening is a process that hardens only the outer surface of a steel part. The inside of the fastener, sometimes referred to as its core, remains soft while retaining its ductility. This combination provides a wear-resistant exterior that protects against abrasion, while the softer core remains ductile and helps prevent cracking or brittle failures when the fastener is in use.

This heat treatment process typically involves heating the fastener in a carbon- or nitrogen-rich environment. At high temperatures, these elements diffuse into the surface layer of the steel. When the part is cooled, the added carbon or nitrogen creates a hardened microstructure in the outer layer. This makes the exterior significantly harder than the softer, untreated core beneath it. In most cases, the hardened layer is only a few thousandths of an inch thick, but it’s enough to greatly improve the fastener’s wear resistance.

Fasteners that are case hardened are often used in situations where the threads or outer surface see a lot of repeated use, like with tapping screws, wood screws, pins, rivets, or hex flange screws. While these parts aren’t typically designed for high-load applications, they perform exceptionally well in conditions where thread integrity and surface durability are essential.

The benefit of case hardening is that it strikes a balance between durability and cost. It provides a hard, wear-resistant surface that protects the threads from damage, while the softer core remains ductile to prevent cracking or brittle failures. This makes case hardened fasteners a practical and cost-effective solution for a wide range of everyday fastening applications.

Understanding how case hardening works will help ensure you're sourcing fasteners that meet your customers' performance and reliability expectations. If you need support identifying or sourcing case-hardened fasteners, our team is here to help. Call us at 800-327-6378 or email us at inquiry@earnestmachine.com.

Misunderstood Fastener Terms & What They Really Mean

Fri, 06 Jun 2025 12:26:28 Z

In the fastener world, terminology matters. A lot.

Using the wrong term in a spec sheet, quote, or conversation can lead to incorrect product selection, confusion between teams, or even performance issues in the field. At Earnest Machine, we talk about fasteners all day, and we’ve noticed a handful of terms that tend to cause confusion more often than others. So, let’s break them down.

Whether you’re training a new team member, double-checking an order, or brushing up on your own industry knowledge, here are several fastener terms that are commonly confused with each other and what they really mean.

Strength Level (Grade vs. Class)

The term strength level refers to how much stress a fastener can handle before deforming or breaking, typically measured by its tensile and yield strength. For inch-sized fasteners, the strength level is referred to as a grade, often specified by the Society of Automotive Engineers (SAE) and the American Society for Testing and Materials International (ASTM International).

SAE grades include Grade 2, Grade 5, and Grade 8. ASTM grades, however, include a wider range of strength levels including A307 B, A325, A193 Grade B7, A490, A449, and A354 Grade BD.

ASTM graded fasteners are often used in the construction of buildings, warehouses, bridges, and cell towers due to their ability to carry heavier loads. SAE Grades can be found in a variety of general-purpose applications such as automotive repairs, machinery assembly, and equipment maintenance where standardized strength and reliability are essential, but the extreme load requirements of ASTM grades are not necessary.

In contrast, lock nuts typically follow a different grading system specified by the American Society of Mechanical Engineers (ASME), which uses letter designations like A, B, C, F, and G. These ASME grades correspond to specific SAE bolt grades. For example, an ASME Grade B or Grade F lock nut is used with a Grade 5 bolt, and an ASME Grade C or Grade G lock nut is used with a Grade 8 bolt. Understanding these grade pairings ensures the lock nut and the mating bolt have matching strength levels for safe, reliable fastening.

Alternately, for metric sized fasteners, the strength level is referred to as a property class. For bolts and screws, common property classes include Class 8.8, Class 10.9, and Class 12.9. For nuts and lock nuts, property classes include Class 4, Class 5, Class 6, Class 8, Class 9, Class 10, and Class 12.

All these strength levels might sound or even look similar to each other, but don’t confuse the numbers (or letters) between the grading systems. For example, Grade 8 (inch) and Class 8.8 (metric) are not equivalent. In fact, Class 8.8 is closer in strength to Grade 5 than Grade 8.

Tensile Strength vs. Yield Strength

As mentioned above, a fasteners strength level is measured by its tensile and yield strength.

Tensile strength describes the maximum stress a fastener can handle before breaking while the yield strength describes the point where the fastener starts to deform permanently. The yield strength is often discussed in relation to another term called the yield point, which is the exact moment on a stress-strain curve when that permanent deformation begins. So, if you apply enough force past a fastener’s yield strength, it might not fracture but it won’t return to its original shape. This can lead to preload loss or failure in the joint or fastened assembly.

For a more in-depth explanation of fastener elasticity, read our Fastener Concepts article titled Strength in Stretching: Explaining Elasticity in Steel Fasteners.

Coarse Thread vs. Fine Thread

While coarse and fine threads are common across our industry, it’s important to remember that they are not interchangeable.

Coarse threads have fewer threads per inch (TPI) and deeper threads. They’re more resistant to stripping, easier to assemble, and better suited for use with softer materials. Fine threads have more threads per inch and a shallower thread depth. They offer better tensile strength and are more resistant to loosening caused by vibration when properly tightened.

Both coarse and fine threads are used across a wide range of fasteners including bolts, screws, nuts, and lock nuts. Lastly, each thread type is suited for a variety of applications. The best choice depends on the material, the environment, and how the fastener will be used.

Hardness vs. Toughness

These are often confused—even though they’re very different material properties.

Hardness describes a material’s resistance to surface deformation, like scratching or denting. While toughness describes a material’s ability to absorb energy and resist cracking or breaking under impact. A hard material isn’t always tough. In fact, extremely hard fasteners may be brittle, making them prone to sudden breakage under dynamic loads or impact. Take heat-treated fasteners, for example. They may offer excellent wear resistance but low ductility. That’s not a flaw; it just means they’re not right for every job. So, don’t assume a harder fastener always means a better fastener. Many applications require a balance of hardness and toughness for long-term performance.

Hex Head Cap Screw vs. Hex Head Bolt

They look nearly identical—but there’s a technical difference.

A hex head cap screw is precision-made, with tighter tolerances and a machined bearing surface under the head, often referred to as a washer face. This surface resembles an integrated washer and helps distribute the clamping load more evenly. A hex head bolt is typically used with a nut and does not have a washer face or as tight of tolerances. It’s often used in less critical applications.

In many cases, using the terms interchangeably won’t cause problems. But when a precise fit and strong, reliable clamping are required, hex cap screws are the better choice because their exact dimensions and built-in washer face help keep parts aligned and securely fastened.

This distinction is especially important when reviewing spec sheets or purchase orders. If someone asks for a “hex head bolt,” they might actually need a hex head cap screw—or vice versa—so it’s a good idea to double-check this information before submitting a quote or fulfilling an order.

Wrap-Up: Why Terminology Matters

It’s easy to assume that everyone is speaking the same fastener language—but even small misunderstandings can lead to sourcing errors, failed joints, or unnecessary costs. That’s why we believe in keeping communication clear, accurate, and helpful.

At Earnest Machine, we’re here to help you get it right the first time. If you need help sourcing fasteners, understanding spec sheets, or building your inventory, let us know. Our team is ready to help and offer solutions that meet your needs.

Give us a call today at 800-327-6378 or email us at inquiry@earnestmachine.com.

Understanding RoHS Compliance and Its Impact on Fasteners

Mon, 21 Apr 2025 14:43:11 Z

In today’s manufacturing and distribution landscape, environmental compliance plays a major role in how products are sourced, sold, used, and disposed of. With manufacturers and suppliers facing increasing pressure to reduce their reliance on hazardous materials across their supply chains, many are paying closer attention to the materials that go into everything they source, distribute, or build. One of the most widely recognized environmental directives impacting sourcing, product design, and manufacturing is the Restriction of Hazardous Substances, better known as RoHS.

But what exactly is this directive?

Understanding RoHS

RoHS is a European Union directive that restricts the use of 10 hazardous substances commonly found in electrical assemblies and electronics. While it primarily applies to the EU, many global manufacturers and suppliers, including those in the US, comply with these standards to meet international market requirements.

The goal of this directive is to minimize the release of hazardous substances into the environment, particularly during disposal, and to reduce the risk of exposure during manufacturing and consumer use. By limiting the presence of these substances in electronics, RoHS helps protect both the environment and human health.

RoHS restricts the use of:

1. Lead
2. Mercury
3. Cadmium
4. Hexavalent Chromium
5. Polybrominated Biphenyls
6. Polybrominated Diphenyl Ethers
7. Bis(2-Ethylhexyl) Phthalate
8. Benzyl Butyl Phthalate
9. Dibutyl Phthalate
10. Diisobutyl Phthalate

Despite their risks, these hazardous materials have historically been used in a wide range of everyday electronic products and materials. Common examples include solder, batteries, electronic components, cable sheathing, switches, thermostats, fluorescent lamps, dyes and pigments, flame retardants in plastic enclosures and computer monitors, PVC, vinyl insulation on electrical wires, and more.

How RoHS Impacts Fasteners

You might not immediately associate fasteners such as bolts, screws, nuts, and washers with electronics. However, in many industries, they are essential components of electronic and electrical assemblies. If a fastener is used in a product that falls under the scope of RoHS, it must also meet the directive’s compliance standards.

RoHS compliance for fasteners often comes down to the materials used in the plating or coating applied to the fastener’s base material. For example, hexavalent chromium has traditionally been used in corrosion-resistant platings, but it is restricted under RoHS. As a result, many fasteners now use RoHS-compliant alternatives such as trivalent chromium or zinc-nickel platings.

What to Look for When Sourcing Fasteners

When sourcing fasteners, it’s important to verify RoHS compliance with documentation such as a Declaration of Conformity or Material Certification from your supplier. A reliable distributor should be able to provide this information and help you navigate the specifics based on your application. At Earnest Machine, we can provide this documentation to our customers upon request.

RoHS compliance also goes beyond being a legal requirement in certain markets; it’s a mark of responsible sourcing and distribution for suppliers and manufacturers. By choosing RoHS-compliant fasteners, you're ensuring that both your products and your customers' products meet environmental standards, keep hazardous materials out of the supply chain, protect human health, and contribute to a more sustainable future.

If you’re unsure whether your current fasteners meet RoHS requirements, it may be time for a closer look. Our Sales team is here to answer your questions and recommend RoHS-compliant alternatives that meet your specific needs.

Have a question for our team? Contact us today! Call 800-327-6378 or email inquiry@earnestmachine.com. You can also reach out to us via our contact form: https://www.earnestmachine.com/contact-us

Look for the Orange Shrink Wrap!

Thu, 03 Apr 2025 13:06:25 Z

At Earnest Machine, we are dedicated to providing quality, high-performance parts to our customers, but we know product damage or loss can occur during shipping, especially with LTL carriers. Providing you with well-packaged shipments is one way we strive to mitigate this pain in the shipping world. Earnest works to ensure product integrity for our customers by using our signature orange shrink wrap for all of our LTL shipments.

After items have been picked at our warehouse they are placed on a pallet and covered using a clear plastic cap. Finally, once all aspects of the order have been checked, the pallet is wrapped tightly using our signature orange shrink wrap. Your receiving departments can immediately know when shipments have been damaged or re-wrapped while in transit by checking to see if our orange shrink wrap is still intact upon receipt.

Please let your receiving department know to sign for a shipment as damaged if they see that the integrity of orange shrink wrap has been compromised on an Earnest shipment. Providing us with photographs (if possible) of any suspect pallet will greatly improve success rates with any damage claims submitted to carriers. We can work together to reduce these costly losses that occur in transit, both in time and dollars.

For any issues with your shipment, contact our team at 800-327-6378 or email inquiry@earnestmachine.com.

Build a Reliable Supply Chain with Blanket Orders!

Tue, 25 Mar 2025 19:15:58 Z

Today's supply chain is often filled with uncertainty, unforeseen shortages, fluctuating commodity prices, and so many other things beyond your control. At Earnest Machine, we can assist you by creating a Blanket Purchase Order, ensuring you have the inventory you need when you need it.

📥 Download our guide on Blanket Orders to discover five ways Earnest can help secure your supply chain!

Ready to lock in your inventory? Call us at 800-327-6378 or email us at inquiry@earnestmachine.com. We're happy to help!

A Look Inside Our Packaging Process

Tue, 25 Mar 2025 17:11:05 Z

Earnest Machine’s packaging services accommodate all your shipping needs. We offer a range of customizable packaging and kitting options. This includes bag size, bag count, kit specs, parts per bag, custom labeling—you name it. We want to exceed your expectations. That’s why we invest in ways to improve our packaging capabilities. Our strong supply chain ensures quality parts, superior service, and timely fulfillment.

📦 Download our Packaging Process Roadmap to see how we offer you the highest quality in packaging services.

Looking to learn more about our packaging capabilities? Call us at 800-327-6378 or email us at inquiry@earnestmachine.com. We're happy to help!

Understanding Prop 65 and Its Impact on Suppliers.

Fri, 14 Mar 2025 08:00:00 Z

Prop 65 is a California law that requires products sold to consumers to be labeled if they contain chemicals known to cause cancer or reproductive harm.

As part of the Safe Drinking Water and Toxic Enforcement Act, this law applies only to products sold in California. In August 2018, California added the requirement that products sold in the state must have a label warning if they contain any of these substances. There are currently around 900 chemicals and substances on this list. The law does not restrict the sale of items that contain these substances; it is designed to create awareness of their presence so the product can be used safely and in the manner in which the product was designed to be used.

Fastener suppliers that ship product into the state of California need to be aware of the substances that are in the materials their parts are made from, along with the substances that are in the plating or coating that are applied to the fastener and in any locking or sealing patches that are applied.

For fasteners distributors of standard grades of hex bolts and nuts (Grades 2, 5 and 8) the Prop 65 labeling requirement typically applies to the plating that is applied to these fasteners. Platings such as cadmium or zinc that is sealed with a hexavalent chromate (commonly listed as Zinc/Yellow) requires a Prop 65 warning label.

Earnest Machine Products has taken the position that we will apply a Prop 65 warning label to products that contain substances that are listed by Prop 65 whether or not the product will be sold in California.

If you are a distributor that sells into the state of California, our label is compliant. If you are a distributor elsewhere in the country, we simply want you to be aware of what it is and why it’s there.

Our goal is to educate our customers and provide as much transparency as possible. If you have questions or would like to learn more, please call us at 800-327-6378 or email us at inquiry@earnestmachine.com.

What Are JIS Specs?

Fri, 14 Mar 2025 08:00:00 Z

The simple answer is that JIS is an abbreviation for Japanese Industrial Standards. JIS specs are standards that are issued by the Japanese industrial standards committee for industrial applications in Japan.

When it comes to metric fastener standards, the answer becomes a little more complicated. As a supplier of metric fasteners, Earnest offers a wide variety of fasteners that are designed to meet the original equipment manufacturer’s specifications. Manufacturers from different regions of the world will reference fastener specs based on their local standards organizations. Equipment that is manufactured in Japan is typically assembled with fasteners that meet JIS standards.

There are four main standards organizations for metric fasteners that original equipment manufacturers can specify to assemble their products:

ISO - International Standards Organization

ANSI - American National Standards Institute

DIN - German Industrial Norms

JIS - Japanese Industrial Standards

The thread tolerancing and fastener strength levels are interchangeable between all of these fastener organizations. So a bolt made to a DIN standard can be assembled with a nut made to an ISO spec (of the same diameter and thread pitch) and an ANSI property class 10.9 bolt is the same strength level as a JIS property class 10.9 bolt.

Where you encounter differences in these standards are in the width across the flats of the head, the thickness tolerance of the head or nut and, in the case of flange products, the diameter of the flange. Fasteners made to the different standards require a different wrench size to assemble them and require different clearances or spacing depending on the standard the fasteners have been made to.

You can count on Earnest to know the differences between the fasteners made to each of these standards and assist you in ensuring you receive the right product for you specific application.

What Is a Place Bolt and How Is It Used?

Thu, 13 Mar 2025 12:00:00 Z

Fasteners that create a "locking" action are commonly used in applications that experience high vibration or flexing to ensure that the assembly does not come loose over time. Many of our customers are aware of the choices that are available in locking nuts (All Metal Lock Nuts, Nylon Insert Lock Nuts, etc) but when it comes to the bolt or screw that is used in the assembly, the choices for a locking screw are limited. The two main styles of locking screws that are used in the industry are the Hex Serrated Flange Screw or a Hex Bolt that has a nylon or chemical patch applied to the threads.

Both options have limitations for use in some applications. For example, Hex Serrated Flange Screws can mar the surface that they are being assembled onto, causing premature rusting. Additionally, chemical patches can be adversely affected when exposed to chemicals or heat. Many of our customers are not aware of another option when it comes to a bolt that can create a locking action within your assembly.

However, Earnest Machine offers Place Bolts which feature a special head design that provides a “locking” action between the head of the bolt and the material being clamped. The combination of the special recessed groove under the head and the slots in the top of the head cause the head to flex as it is tightened, illustrated in figure 1. This creates a spring action in the head that provides additional elastic elongation that is not achieved by standard Hex Head Cap Screws. This spring action also provides increased resistance to loosening in high vibration applications.

Typically, Place Bolts are used on the inside of engines and transmissions where a loose assembly would result in a major repair. Often, this style of fastener is chosen to assemble the flywheel to the torque converter on most transmission assemblies due to the constant speed changes and excessive vibrations that can be encountered within this application.

Earnest Machine’s line of Place Bolts are made to the dimensional requirements of the General Motors standard for Type AA Hex Head Lock Bolts. Additionally, Earnest Machine’s line of Place Bolts are also manufactured from high-strength alloy steel and are through-hardened to the Grade 8 strength level as specified in the Society of Automotive Engineers standard SAE J429.

So, whether you are designing a new assembly or trying to improve an existing one, a Place Bolt is an excellent choice for when you want to achieve maximum resistance to vibration, preventing your assembly from loosening over time, and greatly reducing the likelihood of a major failure or repair.

To learn more about Earnest Machine’s line of Place Bolts, speak to an Earnest Sales Representative at 800-327-6378 or email inquiry@earnestmachine.com

What Are the Differences Between Cut and Rolled Threads?

Thu, 13 Mar 2025 08:00:00 Z

Are the threads cut or rolled? We are often asked this question in regards to how the threads were manufactured on a particular size bolt or screw that we stock. The main reason we are asked this question is because "rolled" threads are perceived to be superior to "cut" threads on externally threaded fasteners.

When a thread is rolled, it means the thread was formed by cold forming the steel by pressing the part between two flat plates or round dies that have the thread pitch machined onto their face. As the part "rolls" through the dies, the pressure applied by the plates creates the thread without cutting or removing material.

A cut thread (also called a machined thread) is made by machining away the material in order to create the thread form. Cut threads, as the name implies, are made by cutting away material.

Customers who ask this question are typically looking for a product that they can offer their customer that has the highest perceived quality.

The reason rolled threads are perceived to be better than a cut thread is:

Thread rolling dies create a thread form that has a rounded root radius.
The rolling operation forces the steel's "grains" to flow with the thread form.
The cold working, of the thread rolling operation, increases the strength of the steel in the threads.

When you are dealing with non-heat-treated bolts (grade 2, grade A, low carbon steel, etc.) a rolled threaded part will have a higher strength than a bolt with cut threads in the area where the threads were formed. When a part is heat-treated (like grade 5 and grade 8 bolts) a cut thread and a rolled thread part will have the same strength. The hardness to which the part is heat-treated determines the strength and not how the threads were manufactured.

The form at the bottom (root) of the thread plays an important role in the "fatigue" resistance of the thread. A radiused (rounded) thread root does improve the threads fatigue resistance. Cut threads are often perceived to create a sharp point at the thread root. A sharp point at the root does make a thread more susceptible to fatigue failures as compared to a thread with a round root. Threads can be cut using a cutting tool that has a radiused point to create a rounded root thread. A heat-treated bolt with a cut thread that has a rounded root radius will have a comparable fatigue strength as compared to a heat-treated bolt with a rolled thread.

The fact is that a cut thread can be manufactured with a radius root that is equivalent to the radius root formed by a rolled thread. So for grade 5 and grade 8 strength level products, a cut thread can have the same fatigue resistance as a rolled thread.

Rolling the thread is a cost-effective way to make threads in high-volume operations. A cut thread is the most cost-effective way to make a thread for low-volume applications.

Earnest standard product is made with threads that are rolled prior to heat treatment. When we make a special, we will cut the threads. When we cut threads, we use cutting tools that will create a rounded root thread form that will provide fatigue resistance equivalent to a rolled thread product.

The best thread form (called the aircraft quality thread) is to roll the threads after heat treatment with a large root radius, called a UNJ thread form. A grade 5 or 8 strength level bolt that has had its threads rolled after heat treatment will provide the highest resistance to fatigue failures. If the parts have been heat-treated after the thread forming operation, the way the threads were manufactured (cut or rolled) does not provide a significant increase in the fatigue resistance.

Can a Hex Tap Bolt Be Used Instead of a Partially Threaded Hex Cap Screw?

Wed, 12 Mar 2025 08:00:00 Z

In applications where the working loads are exerted in line with the length of the bolt (called tensile loads), both a fully threaded and a partially threaded fastener are able to support the same load. If the working forces exceed the strength of the fastener, both of these fasteners will fail in the threads at the same load.

The cross-sectional area (the amount of material that supports the load) is smaller across the thread as compared to across the body (also called the shoulder or unthreaded length). In applications where the bolt is subjected to just tensile loads, having a shoulder on the bolt does not provide a significant benefit.

Applications where there are shearing forces (the working loads are exerted across the bolt) are the ones where the presence of a shoulder will provide increased strength–as long as the shear loading is across the shoulder.

The shear strength of grade 5 and grade 8 hex cap screws (or hex bolts) is 60% of their minimum ultimate tensile strength. Designers prefer to use a partially threaded hex screws in applications that encounter shear loading. The best designs make sure that any shear forces are exerted across the body and not across the threads. The body has a larger cross-sectional area than the threads and therefore the body provides a higher shear strength than the threads. On average, the load required to shear a cap screw is about 1.2 to 1.5 times higher across the body than it is across the threads, for coarse threaded hex cap screws in diameters from 1/4” to 1 1/4”.

Note that in applications where shear forces are encountered and the shear loads are exerted across the threads, then the use of a partially threaded hex cap screw provides the same shear strength that a fully threaded tap bolt provides.

In answer to the original question, a partially threaded hex cap screw should be used in applications where shear forces are exerted across the shoulder, and either a hex cap screw or a hex tap bolt can be used in applications that encounter tensile loads.

What Does DFARS Compliant Mean for Fastener Suppliers?

Mon, 10 Mar 2025 12:00:00 Z

The Federal Acquisition Regulations (FAR) and the corresponding Department of Defense Federal Acquisition Regulation Supplement (DFARS) list the requirements and regulations for companies that do business with the United States government. One of the requirements states that parts (including fasteners) that are made from metals that have been classified as "specialty metals" are to be manufactured and melted in the USA. (or one of the approved qualified countries).

The DFARS “specialty metals” requiring compliance (per DFARS 252.225-7008) are:

Steel with a maximum alloy content exceeding one or more of the following limits: manganese, 1.65 percent; or silicon, 0.60 percent; or copper, 0.60 percent; or containing more than 0.25 percent of any of the following elements: aluminum, chromium, cobalt, columbium, molybdenum, nickel, titanium, tungsten, or vanadium
Metal alloys consisting of nickel, iron-nickel, and cobalt base alloys containing a total of other alloying metals (except iron) in excess of 10 percent
Titanium and titanium alloys
Zirconium and zirconium base alloys

DFARS qualifying countries include:

Australia, Austria, Belgium, Canada, Czech Republic, Denmark, Egypt, Finland, France, Germany, Greece, Israel, Italy, Japan, Latvia, Luxembourg, Netherlands, Norway, Poland, Portugal, Slovenia, Spain, Sweden, Switzerland, Turkey, the United Kingdom, and the United States of America

For fastener distributors that supply steel and alloy steel fasteners that are made to the SAE, ASTM, or ISO grades, the DFARS requirement will apply to:

Grade 8 bolts and screws
Socket head screws made from alloy steel
Property Class 10.9 and 12.9 bolts and screws

Standard hex nuts (grades 2, 5, and 8) and lower strength bolts and screws (grades 2, 5, and property class 4.6 and 8.8) are typically made from carbon steel and the "specialty metal" designation does not apply to these strength levels.

In talking with our customers, we’ve learned that there are different interpretations as to what being DFARS compliant means. Some of our customers will inform us that the parts they are ordering must be DFARS compliant and are to be manufactured from steel that was made and melted in the USA. Technically, the “made and melted in the USA” designation for fasteners that are made from carbon steel is not a requirement per DFARS.

We also have some customers that will note that Commercial Off the Shelf (COTS) items do not need to be DFARS compliant (made and melted in the USA). The definition of what is a COTS item is relatively vague and can be interpreted differently by our customers.

For questions on what items require a “made and melted in the USA” designation, contact us at:

Phone: 800-327-6378
Email: inquiry@earnestmachine.com

Sustainability and the Fastener Industry.

Thu, 06 Feb 2025 12:00:00 Z

Scrutinized by the European Union, regulated by the state of California, and labeled a "carcinogen to workers" by the Occupational Safety and Health Administration (OSHA), zinc yellow with hexavalent chromate has become a term industrial fastener buyers must be aware of, as environmental safety and sustainability become front and center policy in most every global organization.

Zinc yellow fasteners with hexavalent chromate are common, as the plating has attractive anticorrosive properties that can be used for a wide variety of applications. While such fasteners are not outright banned for sale, industrial buyers are avoiding them.

According to OSHA, workplace exposure to hexavalent chromate may cause lung cancer in workers who breathe airborne hexavalent chromate. In addition, it may cause irritation or damage to the nose, throat, and lungs if ingested at elevated levels. Direct skin contact with hexavalent chromate can cause non-allergic skin irritation. Contact with non-intact skin can also lead to chrome ulcers, which are lesions on the hands or in the nasal cavity.

Much of the risk is borne by workers who are in and around the processing and plating of fasteners using hexavalent chromate. Which means that such fasteners, if restricted, may be less available, if available at all. Thus, zinc yellow fasteners may not be available if the demand for hexavalent chromate falls; buyers will need to be prepared to source alternatives. The team at Earnest Machine is ready to help you source alternatives to zinc yellow with hexavalent chromate. Call 800-327-6378 to speak with an Earnest Machine sales representative for available options.

For more information on what steps have been taken to limit the impact zinc yellow with hexavalent chromate has on the environment and human health, download our whitepaper on “Sustainability in the fastener industry.”

What Does It Mean to Case Harden a Fastener?

Wed, 29 Jan 2025 12:00:00 Z

Case Hardening, also known as Surface Hardening, is a heat treating process that makes the outer surface of steel stronger while leaving the inner core of the parts softer, as illustrated in figure 1.

There are 5 different types of Case Hardening processes that you should be aware of:

   •   Carburizing
   •   Nitriding
   •   Cyaniding
   •   Induction Hardening
   •   Flame Hardening

It is important to keep in mind that Earnest Machine will utilize the best case hardening process needed for the specific application, ensuring that your product provides the correct amount of wear resistance, longevity, and avoids embrittlement.

What type of Case Hardened product does Earnest Machine offer?

Earnest Machine offers a complete line of Case Hardened Hex Serrated Flange Product, which includes Hex Serrated Flange Screws, Hex Serrated Flange Lock Nuts, and a line of Large Flange Hex Serrated Flange Lock Nuts. All of which are offered in a wide selection of diameters and lengths, ranging from the most popular sizes used within the industry to those hard-to-find sizes as well.

Why Case Harden Hex Serrated Flange Product?

Hex Serrated Flange Product features serrated teeth under the bearing face of the flange, which works to create the locking action needed when fastening together steel-to-steel components.

The Case Hardening process is important because it increases the surface hardness of the fastener to levels greater than Grade 8 product, resulting in increased surface strength, higher wear resistance, and stronger teeth that “bite” into the material they’re being tightened against.

Without the added bite that the Case Hardening process provides, the tips of the serrated teeth could roll over and become dull when tightened, comprising their locking ability. When fasteners with a locking action are used to fasten steel-on-steel components, you’ll want the added strength that Case Hardening provides, as the teeth will truly grip their installation surface and resist loosening better than standard Grade 5 product.

For more information on Earnest Machine’s line of Case Hardened product, give us a call at 800-327-6378 or email us at inquiry@earnestmachine.com.