Fastener Technology

A Complete Guide to Fastener Strategy – Part 3

Fastener Strategy Part 3

Another key component to a fastening strategy is managing or eliminating high risk fasteners. What are high risk fasteners? High risk fasteners are those which are subject to delayed failure, also known as hydrogen embrittlement (HE).

High-Risk Parts

For a part to be considered high risk, it must have three overlapping elements:

  1. A hardness (core or case) in excess of Rockwell C 38
  2. Subjected to processing, which induces hydrogen gas, such as electroplating or acid cleaning
  3. Assembled in a manner which sustains high tensile or bending stress

Common high-risk fasteners are listed below:

  • Electroplated
    • Property class 12.9 screws
    • Alloy steel grade socket head cap screws
    • Case hardened thread rolling screws
    • Retaining rings
    • Spring pins & clips
    • Conical washers – by themselves or assembled to screws of any grade/class (SEMs screws)

Any of the above listed fasteners can be managed by selecting a finish other than electroplating which does not induce hydrogen along with using mechanical cleaning methods.

For more information on high risk fasteners, check out www.bossard.com or contact us directly at ProvenProductivity@bossard.com.

For general hardware shop here.

Doug Jones
Applications Engineer
djones@bossard.com

August 17, 2018
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A Complete Guide to Fastener Strategy – Part 2

Fastener Strategy Part 2

As mentioned in part one of this series, many manufacturers treat fasteners as an afterthought, but having a clearly defined fastener strategy can offer many benefits in the long term.

Another key point to consider when building a fastener strategy is joint criticality.

Joint Criticality

Looking at each joint and asking yourself, “What happens if this joint comes loose or fails completely?” is a good way to help guide your strategy. Your levels of response may look something like this:

  • Level 1 – Product may cease to function, but can be easily repaired by consumer – generally not a warranty claim
  • Level 2 – Product may fail but warranty claim is unlikely
  • Level 3 – Product may fail and warranty claim is likely
  • Level 4 – Product may fail and injure consumer

Levels 3 and 4 should help guide your strategy in friction control, locking features, and method of assembly. These joints should use controlled tightening methods and tools along with finishes having specific friction ranges engineered into them. If you are unable to incorporate the five times the diameter clamping range into the joint, locking features may also need to be incorporated to help keep things from loosening.

Warranty issues may be worth investigating when building a fastener strategy as well. If loosening or corrosion problems are prevalent, changes to the strategy may help address these claims in the future.

For help with critical joints, or warranty claims, check us out at www.bossard.com or contact us directly at ProvenProductivity@bossard.com.

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Doug Jones
Applications Engineer
djones@bossard.com

August 10, 2018
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A Complete Guide to Fastener Strategy – Part 1

Fastener Strategy Part 1

For many manufacturers, fasteners are somewhat of an afterthought, but having a clearly defined fastener strategy can offer many long-term benefits.

A few key points to consider when building a fastener strategy are as follows:

Metric or Inch System

Many manufacturers in the United States still primarily use inch fasteners for obvious reasons, but if there are any plans to expand into foreign markets, metric fasteners will be a preferred choice. It may seem like a scary proposition to switch, but the right fastener supplier can help!

Finish Requirements

Understanding the life cycle of your product, the environment it will be operating in, and which fastener finishes will satisfy your needs is important. Selecting specific finishes and building them into your strategy can also help prevent part proliferation. It’s also important to understand regulations that may be associated with certain finishes, such as RoHS and REACH. Even if your industry is not bound by these regulations, they may still affect the product you are getting whether you know it or not. If you have been using what you think is the same zinc electroplating for ten years, it’s almost certain that you are getting a different finish now than was being applied originally. You should be aware of things such as reduced corrosion protection resulting from material handling, and different coefficients of friction which could require different assembly torques.

Property Class or Grade

If your bill of materials contains multiple fasteners of the same size and configuration, but with a different grade/property class, you may want to consider consolidating to one part that will work for all strength requirements.

Keep a lookout for future blogs on this topic, and as always, check us out at www.bossard.com or contact us directly at ProvenProductivity@bossard.com to see how we can help you build your fastener strategy.

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Doug Jones
Applications Engineer
djones@bossard.com

August 03, 2018
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Use ecosyn®-plast Fasteners to Improve Your Lighting Industry Application

Using ecosyn-plast in the Lighting Industry

When it comes to working with thermoplastics, ecosyn®-plast is the go-to thread-forming screw. Many lighting industry components are made of thermoplastic materials that must be assembled, which is where this type of screw comes in.

ecosyn®-plast is useful when dealing with thermoplastics due to its ability to be threaded directly into plastic, thereby removing additional components or inserts. This allows you to eliminate potential quality issues, such as deformation, which occur when threading into plastic with inappropriate threads.

Compared with tapping screws, which are used solely for metals, thread-forming screws like ecosyn®-plast have specifically designed threads for use in thermoplastic applications. These types of screws provide improved material flow and thread load-bearing depth, as well as lower drive torque, higher stripping torque, less risk of cracking, and self-locking capabilities. In contrast, the use of tapping screws in non-metals can increase the risk of cracking and lead to improper thread configuration, causing stress fractures in the plastic.

Another ecosyn®-plast advantage for use in thermoplastics is its optimized thread geometry for low-stress generation in joints. This type of screw is also a Bossard catalog part, meaning it is readily available and easy to acquire. It comes in various head styles and available materials to cover a wide assortment of projects.

When to switch from tapping screws to ecosyn®-plast

Certain projects may benefit from converting to ecosyn®-plast from tapping screws. Below is a list of conversion scenarios our customers have encountered in the past. In these situations, Bossard was able to immediately arrange samples, convert to appropriate thread-forming materials, and rectify the issue at hand:

  1. Customer manufactured various lighting equipment, signaling devices, and switch gears.
  2. Customer used imperial sized self-tapping screws for sheet metal to assemble plastic components.
  3. Customer was experiencing base material distortion.

Inappropriate fastener selection, as highlighted in the above scenarios, can result in issues such as cracking, which can in turn lead to costly product recalls. Selecting a suitable thread-forming screw at the start of your project eliminates potential rework issues and reduces hassle by ensuring your product is assembled correctly the first time.

For more information, check out www.bossard.com or contact our engineering department at ProvenProductivity@bossard.com.

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July 20, 2018
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All About Threaded Inserts in the Lighting Industry

Threaded inserts in the lighting industry

Threaded inserts have many valuable uses, especially when it comes to the lighting industry. This type of fastener element creates precise, durable internal threads that are able to withstand higher axial and radial loads compared with self-tapping screws.

There are several factors that will influence the performance of threaded inserts. If you decide to use them and which type to use will depend on the installation method, the material you are using, and what kind of insert support you are looking for.

FASTEKS® makes steel or stainless steel threaded inserts guaranteed to create precise, durable internal threads in workpieces made of light metal alloy and other materials with low shear resistance. They are self-tapping, simple to install and come in six different types, depending on your needs and what kind of project you are working on.

Threaded Inserts Types and Uses

The list below highlights each type and what kind of projects each one is best used for:

  1. The TRISERT®, made out of brass, has a regular head and is used for thermoplastic materials. It has a larger contact surface and can be used in drilled or molded holes. It also has a higher torque and axial forces.
  2. The TRISERT-3®, made out of steel, has a reduced head and is used for light metal and plastics. It can be used in drilled or molded holes. It offers faster installation due to a greater helix angle of the thread flanks, and has corrosion resistance of up to 720 hours to red rust.
  3. The FOAMSERT®, made out of brass, can be either double ended for bidirectional purposes, or have a reduced head. This insert was designed especially for expanded material and wood, and it can be used in drilled or molded holes.
  4. The MULTISERT®, made of brass, is un-headed and particularly suitable for thermoplastic materials. It has a special plain location spigot and has three installation options: press-fitting, ultrasonic insertion or heat insertion.
  5. The MICROBARB®, made out of brass, is particularly suitable for thermoplastics and thin section materials. It’s used especially for applications in electronics and can be installed via press-fitting, ultrasonic insertion or heat insertion.
  6. The HiMOULD®, made of brass, has an open or closed ended design and is used for thermoplastic and thermoset plastics. It is very thin-walled, particularly suitable for applications with low wall thickness. This insert is designed for molded-in applications featuring precise locating pins that ensure proper shut off to prevent plastic flow into the threads compromising integrity.

For more information, check out www.bossard.com or contact our engineering department at ProvenProductivity@bossard.com.

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July 13, 2018
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2 Solutions for Fastening in Lightweight Applications

2 Solutions for Fastening in Lightweight Applications

In 2018, original equipment manufacturers want to create the most innovative and unique products, all while making sure they are as lightweight as possible. Whether its vehicles or electronics, they are all becoming less bulky and less heavy.

To produce these lightweight products, manufacturers are using different materials than what might have been used just a few years ago. Composites like carbon fiber and fiber glass are the new normal when it comes to materials. Metals like aluminum and magnesium are also becoming more popular. But assembling these products can prove to be challenging.

Fortunately, Bossard has a variety of solutions for how design engineers can use fasteners safely and effectively in these relatively new materials. Here are two of our most popular fasteners for these applications.

bigHead

bigHead is one of the best options for fastening when using composite materials. They consist of a standard fixing welded onto a head. These unique fasteners can be secured via adhesives or by embedding directly into the material. They can be used with carbon fiber, steel, stainless, and more materials.

ecosyn-BCT

ecosyn-BCT is not your typical rivet nut. What makes these blind rivet nuts different from others is that they are designed with strategically placed holes around the body of the nut where the rivet nut body will begin to collapse, controlling where the bulge happens. Hence, BCT – bulge control technology. ecosyn-BCT is also great for aluminum, stainless steel, and other lightweight materials

There are four main types of ecosyn-BCT: bulge control, micro, high strength, and multigrip.

For more information about fastening with lightweight materials, contact us at ProvenProductivity@bossard.com.

June 29, 2018
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3 Solutions for Nylon Insert Nut Challenges

Challenges with Nylon Insert Nuts

If you use nylon insert lock nuts in production, it is more than likely that you have run into some issues like the ones pictured below:

Nylon Insert Nut 1 Nylon Insert Nut 2 Nylon Insert Nut 3

Causes

Why does this happen, and usually only in January through March?

The inserts are made of 66 nylon which is hydroscopic, meaning it can absorb moisture up to 8% of its weight. When exposed to temperature extremes and low humidity, the nylon will lose moisture and can shrink slightly and in some cases become brittle. These conditions are not relevant once the insert is installed, but if the nylon has become too dry prior to assembly, then we can see problems like those pictured above.

Certain assembly conditions can contribute to failure of a dried out insert, such as:
• Poor or no chamfer on mating threads
• Long thread engagement
• High assembly speed
• Any combination of the above conditions

If the insert is very dry and brittle, and the mating thread has a poor chamfer, we can see breaking of the nylon, especially if the assembly speed is very fast as with an impact gun.

Long thread engagements coupled with high speeds seem to heat-up the dried out nylon enough to cause it to extrude out the top of the nut. This can happen with properly hydrated nylon as well, especially if the pitch diameter of the mating thread is at the upper end of tolerance (the nylon has to go someplace) but it seems to happen more when the nylon is dried out.

In extreme cases of dried out inserts, such as those run through a bake oven for some type of post finish (zinc flake for example), the inserts may spin freely in their cavity prior to installation. When the mating part is introduced, some inserts may be pushed out of the nut without even forming threads into the nylon ring.

Solutions

  1. Packaging/environment
  • Wherever possible, keep nuts sealed in their original containers until they are ready to be consumed.
  • Do not store more nuts than needed in extreme cold and/or dry environments.
  1. Assembly
  • Check for chamfers on mating parts – a smooth entry into the nylon will lessen potential problems.
  • Avoid long thread engagement if possible.
    • If not possible, adjust speed down to lessen heat build-up.
  • Check speed of assembly – try slowing down the speed if problems occur.
  1. Additional Insert Material
  • If these solutions do not resolve the issues, then consider another type of insert material.
  • High temperature materials are available that are not as sensitive to environment.

For questions, please contact our Engineering team at ProvenProductivity@Bossard.com.

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Doug Jones
Applications Engineer
djones@bossard.com

June 22, 2018
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3 Types of Rivet Nut Tools for Assembly

Rivet Nut Tools for Assembly

Rivet nuts were discussed in a previous blog, but what tools are required to install this type of fastener?

Hand Tools

Smaller rivet nuts can easily be set by hand using simple tools. The nuts are threaded onto a mandrel by hand, inserted into the hole and then using a mechanical lever action, the mandrel is pulled into the tool causing the nuts to collapse on the back side of the hole. The tool must then be manually rotated in reverse to disengage from the nut.

Spin/Spin Tools

These tools are typically pneumatic and have three stages. The first spin assembles the nut onto the threaded mandrel. The nut is then placed into the prepared hole, and the second stage spin collapses the nut on the backside of the hole creating a bulge. This bulge squeezes the material, and secures it into place. The third stage reverses the rotation and backs the mandrel out of the nut. These tools are the lowest cost power tools, but can be a bit fussy about hole size. Too large of a hole can allow the rivet nut to spin and not collapse. The pressure that the nut applies once the bulge is formed is controlled by the amount of torque that the gun creates, so consistency can be an issue if air pressure and/or friction in the threads varies.

Spin/Pull Tools

These tools also have two stages and are typically pneumatic over hydraulic. The first stage spins the nut onto the mandrel while the second stage does not rotate, but instead pulls the mandrel into the tool collapsing the rivet by force. This tool comes in two versions:

  • Pull to pressure – the amount of setting force is set by hydraulic pressure, which can be adjusted on the tool. This style works best if the material thickness is not consistent.
  • Pull to stroke – the amount of setting force is set by the distance of the stroke, which can also be adjusted on the tool. This type of tool works well for materials that are very consistent in thickness.

Some high-end tools incorporate both pull to pressure and pull to force.

For questions about rivet nuts and or tooling, check out www.bossard.com or contact Bossard directly at ProvenProductivity@Bossard.com.

For more shopping options click here.

Doug Jones
Applications Engineer
djones@bossard.com

June 15, 2018
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What are Rivet Nuts?

What are Rivet Nuts

What is a rivet nut and where should it be used?

Rivet Nut

A rivet nut is a special type of nut that is installed into a prepared hole in a piece of sheet metal and secured prior to assembly of a bolt. A special installation tool is required to ‘set’ the nuts into the prepared hole. The nuts are placed into the hole and ‘upset’ on the back side (much like a blind rivet) which secures them, eliminating the need for a wrench.

Standard rivet nuts have been around for years, and work well as attachment points for low strength joints that don’t see much stress. These standard nuts are not high strength and generally cannot support enough clamp load for structural joints.

Rivet Nut Uses

Standard rivet nuts must be used with through holes in harder materials such as steel or aluminum and do not work as well in softer materials like wood or plastic. The bulge formed on the back side must have unrestricted space to form, and will apply pressure to the plate which could overly stress plastic or wood.

Specialty type rivet nuts exist, such as the ecosyn®-BCT which employ bulge control technology to allow them to work in blind holes and/or soft materials such as plastic. There is also a high strength version of ecosyn®-BCT which may be used in structural joints and can create high clamp loads for use with high strength bolts.

If you are currently using weld nuts, or have areas with limited access to one side, consider looking at rivet nuts. Check out rivet nuts and ecosyn®-BCT nuts at www.bossard.com or contact us at ProvenProductivity@Bossard.com for more information. Look for a future blog discussing tools for installation of rivet nuts.

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Doug Jones
Applications Engineer
djones@bossard.com

June 08, 2018
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How to Choose the Best Thread Protrusion Length

Length of Thread Protrusion

How many threads should protrude through a nut in an optimal joint?

The generally accepted answer is 1 to 3 threads. Most externally threaded fastener blanks are manufactured with a header point prior to thread rolling, which leaves the first 1 to 2 threads undersized for ease of assembly. To ensure full load carrying capability for a nut and bolt combination, this rule makes sure we have fully formed threads throughout the entire thickness of the nut.

One notable exception to this is for nuts with a locking feature at the top – or toplock nuts. This includes all nylon insert nuts. For these, it is best to have a minimum of 3 threads protruding through the nut to ensure that the locking feature is engaged on a fully formed external thread. Anything less could compromise the locking affect.

Is there a rule for the maximum number of threads protruding through a nut?

Too many threads is a waste of material, adds unnecessary weight and can be a hazard or cause interference with other components. However, functionally there is no downside to having too much thread protrusion.

When selecting fastener lengths, be conscious of the standard length increments. Metric fasteners are generally available in 5mm length increments up to 70mm and 10mm increments beyond this. Inch fasteners have similar standards. When choosing your fastener lengths, it is best to select the shortest fastener that will consistently give you 1-3 threads protruding through the nut.

For questions, please contact our Bossard engineering team at ProvenProductivity@Bossard.com.

Doug Jones
Applications Engineer
djones@bossard.com

June 01, 2018
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