Next up in our educational series called Know Your Nuts, we’re talking about different types of shaped nuts. The use of shaped nuts varies from type to type, but in general, they all share some aspect of their design with more common standard nuts, with an extra feature added to achieve a specific functionality. Below are four of the shaped nuts most commonly used in construction and industrial applications.

Cap Nuts

Cap nuts are traditional hex nuts with the addition of a smooth dome on one side. These are used in assemblies where protection of the bolt or threaded is important after assembly, either for performance or for safety. Cap nuts can also be used for purely aesthetic reasons, such as in automotive uses or in residential construction, where the end of a bolt could cause an unsightly distraction for the user.

Acorn Nuts

Acorn nuts are a type of cap nut, where the domed side is pointed with a higher crown. This creates greater internal depth, allowing the bolt or rod to be threaded further into the nut.

Square Nuts

As opposed to the traditional hex (hexagonal) nut with its six sides, square nuts only have four sides and look exactly as they sound, a perfect square. Square nuts are typically used where there is an inset or channel in the receiving surface, such as in furniture, railroad applications, or other metal assemblies. The larger surface area of square nuts allows them to more easily resist loosening.

Wing Nuts

Wing nuts feature a head with two “wings” across from each other, making the nut able to be tightened and loosened by hand. Sometimes referred to as a “butterfly nut”, these are mostly used for the purpose of temporary fastening, but can also be found in bicycles and musical instruments.

If you have further questions about shaped nuts, please don’t hesitate to contact us for more information.

In our next edition of Know Your Nuts, we’ll be looking at the two most common types of nuts for wood. These nuts are used in applications where a durable thread is needed but the substrate is too soft for repeated assembly and disassembly. A common commercial use for these products is in the ready-to-assemble furniture industry, where products are shipped flat and need to be assembled by the consumer.

Tee Nuts

Tee nuts feature a thin, long body with a T-shaped flange at one end. The flange, which has 3 or 4 prongs attached to it, digs into the substrate to be flush with the surface, leaving it completely flat. Tee nuts are often used to fasten particle board, composite materials or wood more securely.

Insert Nuts

Insert nuts, sometimes called hex drive inserts, create a threaded socket for a wooden substrate, functioning much like a wall anchor. After a hole is pre-drilled, insert nuts are put into the hole, either by screwing or hammering it in. No matter how the nut is inserted, the external, teeth-like protrusions bite into the wooden substrate, which prevents the nut both from turning and from pulling out.

If you have further questions about nuts or inserts for wooden assemblies, please don’t hesitate to contact us for more information.

For our third edition of Know Your Nuts, we’re going to review the two most common types of structural nuts. The category of “structural nuts” includes heavy hex nuts that meet ASTM A194 GR. 2H, ASTM A563 GR. C, and ASTM A563 GR. DH specifications.

Grade 2H Nuts

Grade 2H nuts are a type of heavy hex nuts that distribute loads over a larger area, due to their size being about ten percent taller and ten percent wider and taller than standard hex nuts. Because Grade 2H nuts are similar in strength to Grade 9 bolts - roughly 20% stronger than typical steel nuts - uses in heavy machinery are quite common, such as assemblies in earth-moving equipment.

Grade DH Nuts

Grade DH nuts are heavy hex nuts made from medium carbon steel that have been heat treated. Designed and recommended to secure F3125 A490 structural bolts in assemblies, these nuts are often marked by the letters “DH”, although they are not required to be marked unless specified by the purchaser.

If you have further questions about structural nuts, please don’t hesitate to contact us for more information.

In our next edition of Know Your Nuts, we’re going to review the different types of all metal lock nuts. Designed to develop a “prevailing torque” between the bolt threads and nuts threads, all metal lock nuts increase the resistance to rotation in an assembly. Unlike nylon insert lock nuts, these nuts are effective in higher temperature environments (withstanding temperatures up to 1,400 °F ), since they’re completely made of metal. Below is a summary of the most common all metal lock nuts available.

Flange Nuts

Flange nuts feature a wide flange at one end that acts like an integrated washer, distributing the torquing pressure placed the nut across the surface of the material it’s being secured to. Often including serrations on the underside of the flange, these nuts are regularly used in assembly lines where the speed of using a single fastener, as opposed to separate nuts and washers, can help increase productivity and overall output.

Keps Nuts

Keps nuts are similar looking to standard hex nuts, but also include an attached, free-spinning washer. The washer is sometimes called a k-lock or star washer. A trademark of ITW Shakeproof, the name Keps is a reference to the “kep” in ShaKEProof, with an “s” typically added because more than one is purchased at a time.

Stover Lock Nuts

Stover lock nuts are single-piece, prevailing torque hex nuts that feature a conical top, flat bottom bearing surface, and chamfered corners. In Stover lock nuts, the locking action is created by distortion of their top threads during torquing, and can withstand severe shock loads and vibration.

Two-Way Reversible Lock Nuts

In a two-way reversible lock nut, a standard hex nut is compressed with two or three indentations on the flat sides of the nut. These compressions can be circular or rectangular, but must be equal distances from each other. In order to create a controlled locking mechanism, the compressions slightly distort the center threads that lock when engaged with the mating bolt or screw. Designed for use with machine screws and low-carbon bolts, the two-way reversible lock nut allows for automatic assembly.

If you have further questions about all metal lock nuts, please don’t hesitate to contact us for more information.

In the first installment of our Everything but the Bolt educational series, we’re taking a look at all different types of nuts. While many applications only need a very basic nut, we’ll review the different types of nuts (both standard and specialty), and give you the information you need to make a decision about which nut is best for your application.

We’ll start with the most quintessential version of a nut on the market - common hex nuts. Below is a description of the different types of common hex nuts available.

Finished Hex Nuts

A finished hex nut is the most basic of nuts - the six-sided nut that almost everyone first pictures in their mind when they hear the word “nut” in an industrial context.  Hex is short for hexagon, referencing the six sides of the nut. These nuts feature internal threading and are commonly used with machine thread bolts and screws, in applications where no “locking” mechanism is required.

Hex Jam Nuts

Hex jam nuts are low profile - usually only about half as thick as a standard hex nut. Commonly used as a type of lock nut, the jam nut is "jammed" against a standard nut to lock the two in place. Jam nuts are also sometimes used in applications where a traditional, larger profile hex nut would not fit.

Machine Screw Nuts

Designed specifically to be used with machine screws, these hex nuts are much smaller sizes than full-size hex nuts and feature flat tops and chamfered corners. Threads can be coarse (UNC) or fine (UNF), and zinc plating is the most common type of finish applied to machine screw nuts.

Nylon Insert Lock Nuts

Nylon insert lock nuts are very similar to basic finished hex nuts, but feature a nylon insert lock to help secure the nut into place. When a nylon insert lock nut is installed onto a bolt or screw, the nylon insert wraps around the threads, protecting the connection from loosening due to vibration.

If you have further questions about common hex nuts, please don’t hesitate to contact us for more information.

Have you ever looked at the head of a bolt and wondered what the markings mean? Maybe there's a series of letters and numbers, maybe just a few lines.

The markings on the heads of bolts serve two different purposes:

1. The markings can indicate who manufactured the bolt. This will vary from manufacturer to manufacturer, but is usually one, two or three characters.

2. The markings can identify the standard to which the bolt was made. For instance, if a bolt head contains three radial lines, then it's a Grade 5 bolt. If it contains five radial lines, then the bolt is Grade 8. If the bolt is manufactured to a particular grade based on standards set by the American Society for Testing and Materials (ASTM), then the marking will show a combination of letters and numbers.

Mudge Fasteners wants to help you decipher these head markings and when you'll need to know them. Download our bolt head markings chart to reference any time you need to figure out the grade of a bolt you're using or looking for. If you still have questions not addressed in the chart, don't hesitate to contact us for help.

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Do you know what the differences between American Standard (imperial) fasteners and metric fasteners are? If you’re choosing fasteners for a particular application, it will be important to know these differences.

Sometimes, the choice between using imperial fasteners or metric fasteners are just a matter of preference. Other times, it may depend on the market you're selling your end product to - if your target market is using metric fasteners regularly, it would be wise to stick with metric fasteners. This is why some manufacturers who are based in the United States where imperial fasteners are standard, but sell more volume in Europe where metric fasteners are standard, choose to use metric fasteners in their products.

If you need to use a wide variety of sizes within a relatively small range for your application, then metric fasteners may be a better choice, since they scale in size more easily than standard fasteners. Also easier is the process of subdividing units of measurement in the metric system.

We created a chart to help you sort through the differences in materials, mechanical properties, markings, thread sizes, tensile strengths and more.

If you still have questions about the differences between metric and imperial fasteners not addressed in this chart, just contact us, we’ll be happy to help.

The primary activities of standards organizations, bodies, standards developing organization (SDO) or standards setting organization (SSO) are developing, coordinating and producing technical standards that address the needs of a relatively wide base user base. Many of these organizations affect the fastener industry, and depending on which parts you’re dealing with, one or more of the organizations listed below may be involved.

ASTM International: American Society for Testing and Materials
ASTM International is the leader in development of international standards around the globe. At least 12,000 ASTM standards that are currently in use throughout the world, improving product quality and enhancing safety of the products bearing the ASTM seal.

SAE International: Society of Automotive Engineers
Based in the United States, the Society of Automotive Engineers (SAE) is global consortium of 138,000+ engineers and technical experts. These experts use their collective knowledge to primary focus on aerospace, consumer automotive and commercial vehicles. The SAE is committed to life-long learning and developing standards via voluntary consensus.

AISI: American Iron and Steel Institute
North American steel producers formed the American Iron and Steel Institute (AISI) over a century ago, earning it the title of the oldest trade association in the United States. AISI advocates for policies supportive of domestic manufacturing that also provide high-quality products to a wide range of customers, with the goal increasing the market for North American steel in both traditional and innovative markets.

ANSI: American National Standards Institute
The American National Standards Institute (ANSI) is best known as the voice of the United States standards and conformity assessment. ANSI oversees creation, promulgation and use of thousands of guidelines that impact nearly every sector of business, with topics ranging from construction equipment to acoustical devices, and from energy distribution to dairy and livestock production. ANSI also offers accreditation programs to assess management systems and conformance standards.

ASME: American Society of Mechanical Engineers
The American Society of Mechanical Engineers (ASME) provides manufacturers with standards for guidelines and tolerances for bolt conformity.  Some types of bolts, like the hex cap screws used in automotive applications, require very narrow tolerances, while construction grade fasteners have more broad tolerances. All of the tolerances are laid out by the ASME specifications are crucial in the manufacturing process.

IFI: Industrial Fasteners Institute
Established in 1931, the Industrial Fasteners Institute (IFI) is a standards organization and publisher based in Ohio, whose primary focus is representing North American mechanical fastener manufacturers. IFI standards are regularly used as a guide to design by machinists, mechanical engineers and manufacturers of bolts, nuts, machine screws and other engineered fasteners.

When it comes to fasteners, IFI does not create standards, but rather manages standards, creating technical information and handbooks to represent, support and protect fastener manufacturers.

ICC: International Code Council
The International Code Council (ICC) is a member-focused association, dedicated to the development of model codes and standards. These codes and standards are used during the design, build and compliance processes of construction, with the goal of creating safe, affordable, sustainable and resilient buildings. Most commodities in the United States, as well as many global markets for commodities, implement ICC code compliance for regulation.

UL: United Laboratories
United Laboratories (UL) aims to advance the building products industry’s goal of achieving safety and innovation. To do this, UL provides cost-effective, reliable product testing and certification with flexible, customized service options.

ISO: International Organization of Standards
The International Organization of Standards (ISO) is an independent, international, non-governmental organization that brings together experts to share knowledge and develop voluntary, consensus-based, market relevant International Standards. With a membership of 161 national standards bodies, ISO supports innovation to provide solutions to global challenges.

DIN: German Institute for Standardization
The German Institute for Standardization (DIN) creates standards that have been developed at the national, European and international level. With DIN, anyone can submit a proposal for a new standard, and if accepted, DIN carries out the standards project according to procedures authored by relevant Standards Committees. When it comes to fasteners, DIN standards are typically only for parts manufactured in metric sizes.

JIS: Japanese Industrial Standards
The Japanese Industrial Standards (JIS) organization is the primary body specifying standards for industrial activity in Japan. The JIS standardization process is coordinated by their Standards Committee and published through the Japanese Standards Association. The most common place JIS standards show up in the fastener industry are in relation to the automotive field.

COLA / LARR: Los Angeles Research Report
While not exactly a standards organization, here in Los Angeles the Department of Building and Safety reviews and approves the use of building, electrical, mechanical products within the City of Los Angeles. If a product is approved by LADBS, a letter is issued that contains a Los Angeles Research Report (LARR) Number, which require renewal every two years. During plan check, an engineer may ask for the LARR numbers of products used to be clearly identified. Fasteners, especially innovative, branded fasteners like those from Elco and DeWALT, are the most common products in construction to require an LARR.

RCSC: Research Council on Structural Connections
The Research Council on Structural Connections (RCSC) is a non-profit volunteer organization. RSCS is comprised of more than 85 experts in the fields of design, engineering, fabrication, erection and bolting of structural steel connections. Research projects funded by the RCSC seek to provide reliability, safety and standard practices for the international steel construction industry.

MS: Military Standard
This United States defense standard is used to help achieve standardization objectives by the U.S. Department of Defense. Often informally called mil-spec, this standardization helps achieve interoperability, ensuring fasteners meet certain requirements of reliability, total cost of ownership, commonality, logistics systems compatibility, and other similar defense-related objectives.

AN: Air Force-Navy Aeronautical
Like MS, AN is applied to fasteners and other parts that meet a specified standard put forth by the Air Force and Navy, generally regarding items used in aeronautical manufacturing. In some cases, MS and AN parts share the same item numbers, but that is not always. If you have any questions about which fasteners meet either MS or AN standards, please contact us.

NAS: National Aero Space
Developed by the aerospace industry, the National Aerospace Standards (NAS) are voluntary standards created by experts on certain subject matters from member companies, who participate in committees and working groups. The library of NAS standards, which contains more than 1,400 documents, cover a wide variety topics including bolts, rivets, washers, screws, nut plates, pins, knobs and more.

If you need help finding parts to meet any of these standards, please contacts us.

A bolt’s size is classified based on a number of dimensions, namely the bolt’s diameter, length of shank, thread pitch, grade, thread length and head size. Bolts can me specified in metric using millimeters, but the standard, internationally-recognized descriptions of bolt sizes are in inches.

If you’re looking to figure out the size of a bolt needed in an assembly and have a bolt that has worked on hand, follow the steps below to identify the dimensions of the bolt:

Step 1: Measure the shank’s diameter

The shaft of the bolt is called the shank, and its diameter is the first dimension used to describe a bolt size. This can be done using calipers or a bolt gauge.

Step 2: Determine the thread pitch

Thread pitch is a designation related to the number of threads per inch on the bolt’s shank. You can complete this measurement by simply counting the number of threads in an inch worth of shank. If the shank is less than one inch, you’ll need to multiply the number of threads to reach a full inch worth of threading.

Step 3: Measure the length of the shank

This is the measurement from where the shank meets the head to the very tip of the fastener.

Step 4: Determine the bolt’s grade

The grade of a bolt is determined by the type of metal used in the manufacturing of the bolt, as indicated by the bolt’s head markings. No one expects you to know all of the head markings by heart, just use our handy bolt head marking chart to make the determination.

Step 5: Determine the shape of the bolt’s head

This should be a simple one. While the most common bolt head is hex (six-sided), some applications require a four-sided square head or the dome-shaped head of a carriage bolt.

Step 6: Measure the length of the threaded portion of the bolt

As opposed to the shank length measured in Step 3, this measurement should specify only the length of the threaded portion of the bolt. One instance in which this would be useful to know is when determining whether you need a standard hex bolt or rather a fully threaded tap bolt.

Still having trouble determining how to measure a bolt for your application? Don’t worry, contact us and we’ll be happy to walk you through it.

Bolts are one of the most used fastener types in the world, finding usefulness in widely varied industries, from construction to automotive, manufacturing to renewable energy. By definition, a bolt is a fastener made up of a head at one end, a threaded shaft in the middle, and a chamfer (slightly bevelled edge which helps with inserting the bolt into nuts) at the other end.

While the terms “bolt” and “screw” are often used interchangeably, the primary difference between the two in general terms is that a bolt passes through a substrate and is captured on the other side by a nut, while a screw threads directly into the substrate.

Here are the most commonly used types of bolts and how they’re used:

Anchor bolt
Anchor bolts, or “anchors” for short, are generally used in concrete or masonry for structural applications. There are many specialized anchors that can be used in cracked concrete per ICC code approvals.

Carriage bolt
Carriage bolts are generally used to attach metal to wood, and feature a square undercut to the head, helping hold the bolt in place after tightening.

Hex bolts

Flange bolt
Flange bolts, sometimes known as frame bolts, are able to distribute the bearing load by utilizing a washer attached to the underside of the head.

Hanger bolt
Hanger bolts are threaded at both ends, with one tip featuring a wood screw point. Hanger bolts are often used in solar racking installation.

Hex bolt / Tap bolt
A hexagon bolt, almost always referred to as just a “hex bolt”, is what most people envision when the word “bolt” is evoked. With a six-sided head, the bolts feature threading for a portion of the shank. When the threading fills the entire length of the shank in a hex bolt, it is then known as a tap bolt.

Lag bolts

Lag bolt
Commonly and maybe more appropriately called lag screws, lag bolts create their own mating thread in wood and other materials when tightened.

Sex bolt
Instead of mating with a nut, sex bolts have a threaded shank that are then inserted into a mating female component. When the fastening components of an assembly cannot be exposed to abrasive threads, sex bolts are the part to use.

Square head bolt
A square head bolt is exactly what it sounds like it is… essentially a hex bolt but with a four-sided head instead of a six-sided head.

Stud bolt
Stud bolts feature hexagon nuts on both ends and operate by fastening components of the assembly between the two bolts.

U-bolts

T-head bolt
T-head bolts, also know as “hammerhead bolts”, feature T-shaped head that is usually inserted into a slot. These types of bolts are often used when insertion into the slot presents an opportunity to lock the bolt into place upon tightening, such as in concrete embed channels.

Toggle bolt
Toggle bolts feature expanding nuts and are used to mount objects to walls where the side of bolt opposite the head cannot be reached once inserted.

U-bolt
U-bolts are shaped similar to staples, featuring a bent design that creates a “U” with partial threading on both ends.

Still not sure which bolt type is best for your application? Contact Mudge Fasteners and let one of our fastener experts help you decide.

Bolts can be either ferrous or non-ferrous, meaning that they either contain iron (ferrous) or don’t contain iron (non-ferrous). So what’s the difference between the two, and what are the characteristics of each?

Obviously, the biggest difference is that ferrous bolts contain iron, while non-ferrous bolts do not. Ferrous metals are magnetic, and are also more vulnerable to corrosion and rust in outdoor environments. Non-ferrous metals tend to be significantly lighter that ferrous metals, which can be seen in the weight difference between materials like aluminum, copper and brass (non-ferrous) versus carbon steel (ferrous).

Ferrous metals, and the bolts made from them, are traditionally stronger and less expensive than their non-ferrous counterparts. Non-ferrous metals, and the bolts made from them, have a lower density, are non-magnetic, and are colorful or able to be made colorful.

Some examples of ferrous metals include non-alloy steels, stainless steel, low, medium and high carbon steel, and some alloy steels, such as chromium and nickel. Examples of non-ferrous metals include copper, aluminum and zinc.

All these factors affect what bolts you should choose for your application. Looking for super-durable, low-cost bolts? Maybe carbon steel bolts would be best for you. In need of something very light and corrosion-resistant? Then look for a bolt in the non-ferrous material family.

If you still have questions about ferrous versus non-ferrous bolts, Mudge is here to help. Contact us for more information from one of our knowledgeable fastener experts.

Carbon steel anchors (ferrous)

Purple aluminum hex cap screws (non-ferrous)

When selecting metals to be joined, especially when selecting what material a fastener in your application should be, galvanic series relationships are a useful guide. This information will help you determine which metals will have a minimal tendency to interact galvanically with each other... i.e. cause galvanic corrosion.

When looking at the galvanic series chart, the further away two metals are from each other, the higher the risk of galvanic corrosion, which can and should be prevented during the design phase.

If you need help selecting the correct fastener material for your application, contact us and we’ll be happy to give you the answers you need.

DURA-CON Fasteners employ a three layer coating system that consists of an inorganic zinc-rich first coat and an aluminum-rich organic second coat. Friction modifiers are integrated into the topcoat, resulting in repeatable torque tension characteristics during assembly. DURA-CON coating provides superior corrosion resistance; withstanding 1500 hours of Salt Spray per ASTM B-117.

In addition to these corrosion resistant properties, the DURA-CON line is made up of Grade 5 fasteners. Why Grade 5? Grade 5 fasteners are listed as 120 ksi fasteners, meaning the tensile strength is 120,000 lbs per square inch. Grade 5 bolts are stronger than A307 zinc, hot dip galvanized or 300 series stainless steel bolts.

With DURA-CON, you get the best of both worlds... high strength, high corrosion resistance, and no galling. To learn more, contact us for information and pricing, or shop online for DURA-CON fasteners at FastenerExpert.us.

There are a wide variety of coatings applied to fasteners for different reasons, but a unique class of compounds in the coating world are what are known as torque modifiers. Torque modifiers are typically added post-plating, thereby modifying the torque-tension properties of the fastener during installation. The clamping load, or tension, is the force that pulls together the parts of the joint. When the clamping load is greater than forces pulling the joint apart, then the joint will not loosen.

Because it is critical for the assembly, friction is a quality parameter for fasteners. Friction can be controlled, in part, by the finish used on a fastener. This is true in narrow ranges, whether high, medium or low friction is desired. Torque modifying finishes can be tailored to user specifications, and different formulations may be used for different applications, such as when different torque is needed depending on the substrate being fastened against.

Do you have questions about applying finishes to fasteners for friction and torque control? If so, check out our finishes overview page or contact us to ask a question.

Applying a finish on your fasteners is a great way to create a cohesive, pleasing appearance. You can choose complementary paint colors sheerly for aesthetics or emulate a "high-tech" look on exposed fastener heads with specific platings. Black oxide finishes can be used to reduce glare, or a shiny, bright look can be achieved with a chrome finish.

Applying specific finishes is also an effective way to avoid confusion and make the identification of fasteners quicker and easier. Some fasteners for right-hand or left-hand applications may appear identical but really are not; other fasteners vary in the slightest dimensions also appear identical. Color code these fasteners as part of the finishing process and identifying the differences between them has never been easier.

Still have questions about applying finishes to fasteners for appearance? Check out our finishes overview page or contact us to ask a question.

So often, engineers pour a great deal of time, thought and effort into which type of fastener would be the best fit for a certain design, and then proceed to overlook the importance of which finish is being applied to that fastener. Finishes perform a variety of functions, not only affecting appearance, but also determining performance capabilities in some circumstances. The following factors should be considered when deciding which is the best fastener finish for your particular application:

Appearance
Create a cohesive and pleasing appearance with paint, black oxide, chrome and more.

Identification
Avoid confusion with specific finishes. Color coding has become an important part of the finishing process.

Friction
Fastener finish is important for joints assembled using torque control, which requires a predictable and repeatable clamp load. 

Improve Corrosion Resistance
Some thought should be give to the desired service life of the fastener and the environment in which it will it be operating. The proper finish can extend the life of the fastener against various corrosive environments.

Still have questions about when and why finishes should be applied to fasteners? Check out our finishes overview page or contact us to ask a question.

Fastener Engineering Magazine recently interviewed our own Marisa Mudge about how Mudge Fasteners is dealing with the COVID-19 crisis, while still maintaining operations to serve customers in essential industries, such as medical ventilator production. Listen to the interview below.

From the Fastener Engineering website:

In this audio interview, Fastener Engineering speaks with Marisa Mudge, marketing manager with Mudge Fasteners, Inc., a nationally recognized and essential component supplier.

Mudge Fasteners is still open for business and, to this end, Marisa kindly agreed to discuss the measures the company has put into place, given the current health concerns and challenges related to COVID-19.

To learn more about Mudge Fasteners — which was founded by Marisa’s father, Paul Mudge, in 1975 — read this company profile.

This article was originally featured in Fastener Engineering Magazine.

Imagine you’re an engineer with the freedom to create any design you’d like with only one catch: you can only use two types of fasteners. Would this limit or simplify your design?

Simple is often best. Typically, design engineers can save costs and meet project deadlines by only using standard fasteners and limiting the type used for each application.

For Marisa Mudge, marketing manager with Mudge Fasteners, Inc. (a supply company owned by her father), the answer is simple: “The idea of designing with limited, standard parts is absolutely brilliant because of the significant time and cost-savings it, ultimately, provides,” she says.

Although Mudge is not a design engineer, she’s worked full-time at Mudge Fasteners for more than a decade (and much longer, if you add in the time she helped her dad at the company in her adolescence). So, she knows a thing or two about fasteners.

When she met an engineer from Hewlett Packard on a plane one day — who is limited in his designs by the use of only two screws — Mudge was impressed by the company’s mandate.

“One of the biggest problems companies face related to fasteners is lost parts. Typically, fasteners are the smallest part at a job site and minimal efforts are spent tracking this inventory…so the screws or bolts get dropped at construction sites, lost on manufacturing floors, or accidentally left in pockets,” she shares. “So, a project with only two standard fastener choices would have a real advantage.”

A few lost fasteners may seem like a small problem, but replacement costs can add up quickly.
“Some standard fasteners run in excess of a dollar or two a piece,” Mudge says she often gets calls from companies that suddenly need 200 or 300 additional parts after ordering 20,000 for a job. This means a lost advantage in bulk purchasing power. “Generally, these costs are significantly higher for custom fasteners.”

What makes matters worse are the lead times. “Customized parts can take two or 20 weeks to replace, which can seriously affect project deadlines,” she says. “And most of the calls we get are not directly from the design engineers or project managers. Rather, the calls come from the workers out in the field who are under pressure to have a product manufactured or installed by a certain date. The concern is the workers may develop a work around.”

What Mudge means by “work around” is the next best solution but, possibly, not the ideal fastener for the job. “This is why it’s extremely important to consider fasteners at the design stage of a project and plan for challenges during construction, such as lost parts,” she says. “It’s also why a couple of standard fasteners per application would generally make life a lot easier.”

There are additional reasons why pre-planning is important. For example, Mudge worked with one client who insisted on fasteners that would perfectly match the color of a project’s auditorium walls — and at a guaranteed cost. “In this case, we had to provide raw, non-customized fasteners because our vendor was unable to guarantee the paint required to match that exact color.”

The reason for this was simple: the environment the fasteners would be exposed could affect the paint and color, so to guarantee it was impossible. “In such cases, the architectural aesthetics can really drive up the cost of fasteners,” she explains.

The conditions fasteners are subject to, such as moisture or high heat, can also affect their reliability. “This is where standards come in, which can sometimes be an issue with custom fasteners,” says Mudge. “Standards organizations specify and test the properties of fasteners, but there are several different organizations and standards that should be adhered to depending on the application.”

For example, the Society of Automotive Engineers or SAE is primarily focused on safety regulations for the aerospace, automotive, and commercial-vehicle industries. The American Society of Mechanical Engineers or ASME provides manufacturers with guidelines and tolerances that their bolts must conform to. (View a list of the main standards organizations at mudgefasteners.com/standards-organizations.)

Marisa Mudge and her father, Paul, at the Mudge Fasteners headquarters in California.

Typically, standards are categorized into:

• Products – the different types and product gaging (ex. ASME B18.2.1)

• Materials and performance – specifications and strength (ex. ASTM A325)

• Testing – test equipment protocol and methods of testing (ex. NASM1312)

• Quality – fastener reliability (ex. ISO 9000)

“Consensus standards offer many benefits that are not covered by non-standard fasteners,” explains Mudge. This includes guidance and policies backed by significant research and expertise. “Although an engineer can anticipate performance based on material when using a custom fastener, the part is not required to meet any of the design specifications set forth by the consensus organizations, so there’s risk involved.”

Mudge recommends working with a vendor partner during the design phase of an application to identify standard parts and the ideal choice for an application.

“Typically, fasteners are the least expensive component for a job and given little forethought. But this doesn’t mean they’re unimportant,” she says. “In fact, quite the opposite is true. These small components hold an entire application together — which is one reason standard fasteners that are reliable and readily available are often the ideal choice.”

One other reason standard fasteners are ideal is to avoid unused inventory, which can happen as a product changes or evolves.

“Hewlett Packard is at an advantage by allowing engineers to design with only two screws because, even as their products change or improve, the company is never going to be stuck with dead inventory or 20,000 fasteners that they bought because procurement and design were not on the same page,” says Mudge. “It’s a wise business decision.”

Going standard
The advantages of designing applications with standard parts and limited fasteners.

• Minimizes problems with inventory management

• Eliminates risk of dead stock related to project design changes

• Reduces procurement delays

• Facilitates stock replenishment (and re-order points are simple to calculate)

• Mitigates “stock out” occurrences because of limited product range

• Saves time and costs

Want to know more about how “going standard” can help your business? Contact us to find out!

A fastener drive is a set of shaped cavities and protrusions on the fastener head that allows torque to be applied to it, typically also involving a mating tool, such as a screwdriver. Usually the drive serves a functional purpose, but sometimes its purpose is sheerly decorative. Understanding the differences will help you decide which style to choose, so follow our guide below to find the best drive for your application.

Slot
The slot screw drive has a single slot in the fastener head and is driven by a "common blade" or flat-bladed screwdriver. It was the first type of screw drive to be developed, and for centuries it was the simplest and cheapest to make. The slotted screw is still used in some applications where little torque is needed, but is not well suited to installation with power tools.

Cross
A cross or double-slot screw drive has two slots, oriented perpendicular to each other, in the fastener head; a slotted screwdriver is still used to drive just one of the slots. This drive's primary advantage is that they provide some measure of redundancy - should one slot be deformed in service, the second may still be used and the tool can not slip out.

Phillips
The Phillips screw design was developed as a direct solution to a number of problems with slotted screws: increased cam out potential; precise alignment required to avoid slippage and damage to driver, fastener, and adjacent surfaces; and difficulty of driving with powered tools.

Pozidriv
The Pozidriv is an improved version of the Phillips screw drive, and is designated "Type IA" by ANSI standards. It was specifically designed to allow more torque to be applied and greater engagement than Phillips drives. As a result, the Pozidriv is less likely to cam out.

Phillips Slotted
Some screws have heads designed to accommodate more than one kind of driver, sometimes referred to as combo-head or combi-head. The most common of these is a combination of a slotted and Phillips head, often used in attaching knobs to furniture drawer fronts. Because of its prevalence, there are now drivers made specifically for this kind of screw head.

Robertson (Square)
A Robertson, or square screw drive is specified as ANSI Type III Square Center and has a square-shaped socket in the screw head and a square protrusion on the tool, both of which have a slight taper. Robertson screwdrivers are popular in woodworking, and are easy to use one-handed, since the tapered socket tends to retain the screw, even if it is shaken.

Hex Socket
The hex socket screw drive has a hexagonal recess and may be driven by a hex (Allen) wrench, hex screwdriver or hex bit. Their lever arch mechanisms allows for increased tightening torque, and contact surfaces of the fastener are protected from external damage.

Hex Pin
A hex pin screw drive is a security drive that features an extruded pin to make the fastener more tamper resistant. By requiring a tool with a corresponding hole to drive the fastener, it can prevent attempts at turning the screw with a small flat-bladed screwdriver.

Torx (Star)
Torx drive fasteners feature a 6-point star-shaped pattern, designed to allow for higher torque with superior resistance to cam-out. Torx fasteners are commonly used in automobiles, computers, consumer electronics, and are becoming more popular in for use in construction applications.

Torx Pin
A Torx pin drive, also known as Security Torx or Tamper-Resistant Torx, features the same benefits as a standard Torx drive, but also includes a post in the center of the head that prevents a standard Torx driver from being inserted. This is the most common type of security drive available.

One-Way
One-way fasteners can be turned only in one direction. They can be installed with a standard flat-blade screwdriver, but cannot be easily removed using standard tools. One-way screws are commonly used in commercial restroom fixtures and on vehicle registration plates, to prevent vandals from tampering with them.

Tri-Wing
Tri-wing fasteners, also known as triangular slotted fasteners, feature three slotted "wings" and a small triangular hole in the center. Unlike the "tri-point" fastener, the slots are offset, and do not intersect the center of the fastener. The design is usually seen on electronics equipment and sometimes in the aerospace industry.

Tri-Groove
Tri-groove is a security drive with a flat-topped conical head and three short, non-adjoining radial slots in the center, and are installed using a special socket that grips the indentations along the outside to turn the fastener.

Spanner Head
The spanner fastener drive features two round holes opposite each other to prevent tampering. This type of drive requires a specialized driving tool called a "spanner driver", and is often seen in elevators and restrooms.

Need help determining which drive will work best for your application?
Contact us and we’ll be glad to help.

Mudge Metric Line Card (PDF)

Mudge Metric Conversion Chart and Selection Guide (PDF)

Metric fastener sizes are specified by diameter, pitch and length, in millimeters (mm). Sizing for nuts will appear as diameter and pitch. If the pitch isn't specified, the fastener is assumed to be coarse thread by default. Here is an example of how metric sizing:

M10-1.0 x 20

Taking a closer look at this description, let’s explore its meaning:

• M = This designates the fastener is a metric size

• 10 = The nominal diameter in millimeters

• 1.0 = The thread pitch, or distance between threads, in millimeters

• 20 = The fastener’s length, in millimeters

Now, let’s look at an example illustrating how a coarse thread fastener would be labeled:

If the size is M10 x 25, that would mean that the diameter is 10 mm. Since there is no thread pitch listed, the fastener is assumed to have a coarse thread. The 25 indicated a length of 25 mm. A matching nut would be labeled M10, which also doesn’t require a thread pitch since it’s a course thread fastener.

If you generally work with fasteners using imperial measurements (inches, etc.), the pitch notation can be a confusing. Just remember that thread pitch means the distance between adjacent threads, so in the example at the beginning of this article, the 1.0 thread pitch indicates that the distance between one thread and another is 1.0 millimeter.

Imperial measurement fasteners are classified by threads per inch, so a 1/4-20 bolt has 20 threads per inch (TPI), while a 10-24 screw has 24 threads per inch. You can determine the threads per inch of a metric fastener by multiplying the millimeters by 0.03937, and then dividing 1 by that number.

At Mudge Fasteners, we’re here to help. If you have questions about any of the dimensions of metric fasteners, or need help with conversions, just contact us. We have also created some handy brochures to assist you, including our metric line card and metric conversion chart with selection guide.