Locking Fastener Methods to Secure Your Application: Nylon Patches & Plugs

Locking part 3

Part three of our series on fastener locking methods will focus on nylon patches and plugs.

Nylon Patches

Nylon patches have some similarities to adhesive patches as they are both applied prior to arriving at the customer and they cannot be forgotten, but this is where the similarity ends.

Nylon patches are a hard, nylon material that is applied as a powder, and then melted into the threads with heat. The nylon material is typically NOT a 360° patch, but only applied on one side of the threads. The material is soft enough to form threads into it during assembly, but hard enough to create additional friction on the opposing side of the patch. This patch has some re-usability as it does not cure like an adhesive after assembly, but remains hard. Most manufacturers claim some locking effectiveness up to 3 to 5 times of complete dis-assembly and re-assembly. Applications which require minute adjustments without complete dis-assembly can benefit from this style of patch.

nylon patches








Nylon Plugs

Nylon material can also be added to the threads in the form of plugs or strips.

nylon plugs

nylon plugs 2







This method of application requires machining of the screws and pressing in the nylon plug or strip. While slightly more expensive to manufacture, some customers still prefer plugs over patches and believe they achieve improved performance with this style.

Some notable advantages of nylon over adhesive are a longer shelf life under ideal storage conditions and the possibility to re-use.


For more information on nylon locking features, or to help you decide which locking method is right for your application, check out www.bossard.com or contact us at ProvenProductivity@bossard.com.

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Doug Jones
Applications Engineer

November 30, 2018
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How the Titanic and the Iceberg Relates to Fasteners

Titanic Fasteners

When thinking about the tragedy of the Titanic, it is common to remember one of the major causes of its sinking: the iceberg. An iceberg is deceiving as it hides about 85% of itself below the surface of the water, making one believe that it is much smaller than it really is. The same can be said for the true cost of a fastener.

Factors of Fastener Cost

Fastener costs that can often be hidden below the surface may be labeled as an “activity cost”:

  • Purchasing
  • Receiving
  • Quality control
  • Put on stock
  • Picking and preparation
  • Checking invoices/payments
  • Yearly stocktaking

These activities have a cost associated with them for each part number in your Bill of Materials (BOM). By reducing part numbers in your BOM, you can cut your total fastener cost considerably. Don’t let your ship sink! Check out the Bossard Cost Savings Calculator, which allows you to calculate your potential savings by making Bossard your preferred supplier. Contact us at ProvenProductivity@bossard.com for help chipping away at your iceberg!

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Doug Jones
Applications Engineer

November 09, 2018
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Why You Should Be Prepared for Industry 4.0

You may be hearing about the fourth industrial revolution, otherwise known as Industry 4.0. What does this mean? Ever since technology became integrated into the workplace during the third industrial revolution, companies have become more efficient.

To keep up with the ever-changing industry, more and more companies are using digitalization to streamline their systems. Now that we are getting deeper into the technological age, the integration of advanced technology such as cloud computing, 3D printing, artificial intelligence, and so much more is being integrated into the workplace.

What does this mean for you and your company? This means utilizing advanced technology and implementing it into the workforce or workplace. Industry 4.0 and IoT will create transparency which creates maximized efficiency and reduced downtime.

Bossard has created Smart Factory Logistics which keeps you at the cutting edge of the industry. If you would like to learn more about Industry 4.0 and manufacturing, check out our other pages such as the 7 steps to get ready for Industry 4.0 and digitalization or how will Industry 4.0 impact your supply chain?.

January 05, 2018
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Why Process Control is Important for Fasteners

How Important is Process Control for Fasteners

Many fastener manufacturers are faced with several different customer requirements or international standards. This leads manufacturers to create sampling plans to detect nonconforming product during mass production or final inspection. There are also several different AQL (Acceptance Quality Limit) levels according to batch or lot sizes. Do you think relying on final inspection sampling is the best idea? Even if they choose various samples from multiple bins of the same batch?

Fastener manufacturers are no different than any other industry. Speed, delivery, and quality are key, and most companies have been driving lean methodologies and efficiency tools into manufacturing processes. But does this have a negative impact on quality? Maybe, but most fastener manufacturers do still maintain minimum sampling plans that are fairly aligned with some international standards for mass production.

So what is a good detection method to minimize nonconforming product during the manufacturing process? Contact us through ProvenProductivity@bossard.com, and see what quality processes we encourage Bossard manufacturers to use to ensure quality fasteners for our customers.

Tony Peters

Quality Manager

October 27, 2017
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6 Types of Bolt Failure and How to Prevent It

Designing fasteners into your application requires a complete analysis of the joints to make sure nothing was missed. Understanding the types of failures that can occur will help with this analysis. Read on to see how to prevent bolt failure.

Failure Type of Failure Solution
  Overloading (stretching)

– Make sure that the appropriate material and grade was used

– Make sure your design is well understood and that the bolts are not overstressed


– Make sure that the appropriate material and grade was used

– Make sure your design is well understood and that the bolts are not overstressed

– Make sure that the fasteners are well-tightened


– Use a lubricant

– Avoid fastener misalignment

– Avoid high speed installation – keep installation speeds low

– Avoid rough surface – smooth finishes

[1] Shearing

– Make sure to re-evaluate tightening strategy

– Threaded section in shear plane – use shank instead

[2] Galvanic corrosion

– Avoid use of dissimilar metals

– Prevent moisture entrapment

– The fastener should be the cathode (more noble)

  Hydrogen Embrittlement

– Eliminate susceptible alloys, hydrogen, stress (service or residual)

– Use non-electrolytic platings

– Increase bake times

– Risk is never eliminated


For further information on these or other types of bolt failure, please feel free to contact us at ProvenProductivity@bossard.com


Fadi Saliby
Technical Sales Director


[1] http://www.learneasy.info/MDME/MEMmods/MEM30006A/Bolted_Joints/Bolted_Joints.html

[2] https://en.wikipedia.org/wiki/Corrosion

September 15, 2017
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What Your Bolts are Telling You

When identifying nuts and bolts, there is some information that can be gathered about them simply by looking at the part. Here is a quick overview of how to identify nuts and bolts by taking a quick glance.

Metric bolts have the class marked on the bolt and the nut. This is identified by two numbers separated with a decimal point. This is an easy way to determine that the bolt thread is metric. A line below the property class is used to indicate if boron was used in the manufacturing of the base material. Common classes are 8.8, 10.9, and 12.9.

Inch bolts are identified by lines on the head of the bolt. If there are no lines but a head marking, that is a Grade 2 bolt. Grade 2 is soft and not heat treated. Three equally spaced lines 120 degrees apart are used with a Grade 5 bolt. Six equally spaced lines are used to identify a Grade 8 bolt. The use of boron steel is identified by equally spacing the identification marks over 180 degrees on the bolt head face.

Metric nuts are identified with a number. This number should be the same as the first number on the bolt. Inch nuts have multiple ways to be identified depending on the standard produced to. If not explicitly stated (number on the face for the grade of the material) the nut will be identified by lines. Grade 2, non-heat treated parts, will have either no line or one line on one of the faces of the nut. Grade 5 nuts will be marked with two lines that are 120 degrees apart. Grade 8 parts will have two lines that are roughly 30 degrees apart (similar grades have 3 equally spaced lines; these are manufactured to alternative standards).

Many times, the bolt head will have a manufacturer’s mark as well. The manufacturer’s mark can be very telling when processing issues with problem parts. If the head markings between two parts are different, they would not be from the same manufacturer, let alone the same manufacturing lot.

More information about identifying nuts and bolts can be found on Bossard’s Website or by contacting us at ProvenProductivity@bossard.com with any questions.


Brandon Bouska
Application Engineer

September 08, 2017
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Quick Guide to Serrated Flange Nuts

A hex flange nut with serration is a nut that is formed with an enlarged circular base that flairs out from the bottom of the nut. When the nut is torqued into place, the bearing surface of the serrated base displaces the material of the mating surface. This forms a locking effect which resists vibrational loosening.

Because of the seated surface, the nut will require a greater amount of torque to loosen adding to the locking feature. The flanged surface will span an oversized or a poorly aligned hole and provides a more uniform bearing stress to clamp force ratio than a finished hex nut.

Serrated hex flange nuts are available in Grade 5 and Grade 8.

When using serrated hex flange nuts, the bearing surface will be damaged as the serrations dig, which can cause concerns for engineers. A painted surface will become chipped exposing the material. This may cause accelerated corrosion of the assembled parts.

Contact us at ProvenProductivity@bossard.com for more information on multi-functional fasteners.

Joe Stephan
Application Engineer

September 01, 2017
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4 Essential Steps to Choosing a Fastener Finish

Choosing a Fastener Finish

When choosing a fastener finish, there are many factors to be considered. But if you follow these four essential steps, finding the perfect fastener finish becomes much easier.

  1. Corrosion resistance
    The necessary corrosion resistance depends on the operating environment of your product. Is the product protected from the elements, or is it exposed to moisture or weather changes? Industrial or agricultural environments where dirt, debris, or chemicals encounter fasteners can also be a factor.


  1. Friction control
    Friction control is often overlooked when choosing a fastener finish, but it is a key component. If you don’t know the friction of your fastener finish, then you don’t know how much torque to apply to the joint to achieve your desired clamp load. Using torque values from a chart can be dangerous and lead to premature joint failure.


  1. Current regulations
    Recent regulations on chemicals such as hexavalent chromium have also dramatically changed the composition of fastener finishes over the past five to ten years. Your industry may not require compliance to RoHS or WEEE regulations, but there is a good chance that your fastener finish is different than it was ten years ago. Know the difference and how it affects your end product.


  1. Cost
    Finally, cost is always a factor. A lot of designer finishes exist out there to address all of your concerns, but you will pay for the technology. Educate yourself on the actual needs of your design and what is available. Then, you should be able to arrive at the proper finish for your product.

Contact us at ProvenProductivity@bossard.com for more information on fastener finishes.


Doug Jones
Applications Engineer

August 25, 2017
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Why Do Bolts Break?

Have you ever broken a bolt? How do you determine why the bolt failed?

One of the most common types of failure is overloading. All bolts have a maximum load that they can bear before they begin to yield, and generally this load is applied in the form of torque. If friction is lower than expected, the bolts may yield before reaching the prescribed torque. When a bolt yields, it will stretch, causing a “necking down” in the threaded area of the clamping zone that is not engaged into the mating threads. Assemblers can usually feel the bolt stretching as it will take many more rotations of the wrench before either breaking or stalling the wrench. If the bolt breaks, you will see an obvious reduction in surface area at the break where the bolt has necked down.

If a bolt breaks after it has been assembled, there a couple of failure modes that should be considered.

How does fatigue failure occur? Fatigue failure happens when the bolts have not been tightened properly, or have loosened up during its service life. If enough force is acting on the loosened joint during use of the product, bending stresses can weaken the fastener, eventually causing it to fail. This can normally be diagnosed by a fastener expert by close examination of the broken fastener and the mating components.

A third, less common type of failure is caused by hydrogen embrittlement. This type of failure is considered a delayed failure and will always happen after assembly. The hydrogen embrittlement time to failure is typically within 48 hours. The break will almost always be directly under the head of the fastener and not in the threads. The head may break off completely, or it may simply crack enough to relieve clamp load, and remain attached. Either way, the joint has failed and is not safe. This type of failure, while not common, almost always occurs in very high strength fasteners, or case hardened fasteners that are electroplated.

Contact us at ProvenProductivity@bossard.com for more information on failure analysis of bolted joints.


Doug Jones
Applications Engineer


August 18, 2017
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Vibrational Loosening

What is vibration, and how does it contribute to the loosening of fasteners? The answer may seem obvious, but understanding the mechanics of vibrational loosening can help us take steps to prevent it.

Imagine a block of wood on a ramp. The angle of the ramp is low enough that the block of wood does not slide down the ramp. Now, we repeatedly wrap on the ramp with a hammer, not too hard, but enough to make the block of wood jump a bit and slide down the ramp. This is like how vibration causes threads to rotate loose, or “down the ramp”. When vibration occurs, it briefly, but repeatedly, lessens the pressure between the block and the ramp (or thread flanks) and the block naturally slides down the ramp.

Now, if we use a heavier block of wood it takes more vibration to cause the block to slide down the ramp. This is similar to adding more clamp load into the joint. But, given enough amplitude and frequency of the vibration, we still get the same result – the block sliding down the ramp, or rotational loosening.

Lastly, if we clamp the block of wood to the ramp, so that there is pressure on the top of the block, it is not allowed to bounce and lose friction on the bottom side, and it does not slide down the ramp. So, how can we simulate this condition in a threaded joint? Your normal nut and bolt joint will always have thread tolerances to ease assembly, creating gaps on the back side of the threads. However, if we can use thread forming screws, which make their own threads into the mating part during assembly, we have no thread gaps.

Thread forming screws, while not the solution for every joint, work very well in situations where vibrational loosening is a high risk.

Contact us at ProvenProductivity@bossard.com for more information on solutions for vibrational loosening.

Doug Jones
Applications Engineer

August 11, 2017
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