Considerations for selecting the proper fastener materials for your application

Fastener Materials

Share This Post

Share on facebook
Share on linkedin
Share on twitter
Share on email

Fasteners are often an unnoticed, yet integral, part of any application that most people don’t give much consideration to until they need to use one. The material the fastener is made from is equally as important as their size specifications. Fasteners can be manufactured from a wide variety of materials and further enhanced by a range of coatings, platings, and finishing treatments. No matter what type of fastener you need – screw, peg, rivet, bolt, clamp, etc. – selecting the proper material for the intended application is critical to both performance and reliability.

In order to select the proper material for a fastener numerous factors need to be taken into consideration. There are four main criteria that need to be evaluated in order to select the proper fastener material. Those are:

  1. The load or stress
  2. Strength
  3. Resistance properties
  4. Temperatures

The load or stress

When selecting a material to fabricate your fasteners from you must take into consideration the proof load, the yield strength and the tensile strength of the particular material.

  • The proof load, or stress, is measured in pounds per square inch and refers to the minimum acceptable load that the fastener will withstand. When it comes to fasteners, pure steel and low carbon steel have the lowest acceptable proof load.
  • The yield strength refers to the load at which the fastener will become permanently deformed.
  • The tensile (or ultimate) strength refers to the load that will break the fastener.

Strength

The strength properties will be very different depending on which type of material is used to create the fastener as well as the final shaft length of the fastener, plus a few other considerations.

Typical metal strengths at room temperature:

MaterialUltimate/Tensile (ksi)Yield Strength (ksi)
Inconel 718210175
Monel K500160110
Moly158130
Titanium Grade 5148138
Inconel 62514484
Tungsten (99.5%)142109
Super Duplex 250712582
Duplex 220511080
Tungsten Alloy94-10075
Molybdeum9490
Inconel 6009337
Zirconium 7058973
Aluminum 7075-T68373
Monel 4008332
Titanium Grade 27050
Nickel 20060-8515-45
Zirconium 7026847

Typical polymer strengths at room temperature:

MaterialUltimate/Tensile (psi)Yield Strength (psi)
PEEK (extreme)4790051000
PEEK (glass fiber)2280026000
PEEK (unfilled)1600013600
Vespel12500
Torlon PAI22000
PVDF5000-80006500-8000
PTFE39001450
PFA36002000

Typical ceramic strengths at room temperature:

MaterialUltimate/Tensile (ksi)Yield Strength (ksi)
Zirconia75
Alumina30

Resistance properties

Corrosion wears metal down due to the material’s interaction with chemicals in the surrounding environment. The most common type of corrosion is oxidation, which is caused when the metal reacts to oxygen and rusts. Typically to combat corrosion, the fasteners will need a protective coating applied such as chrome or zinc. Otherwise, if applicable, the fastener could be manufactured from a material that does not corrode such as non-ferrous metals or plastic alloys.

Temperatures

You need to take into consideration the average temperatures that the fastener will be required to operate in to be sure that the material can handle it. Obviously plastics and non-ferrous alloys have no place in environments with extremely hot temperatures. Others can become brittle in extreme cold and lose their ductility.

What are the most common materials used to manufacture fasteners?

Here is a quick list:

  • Metals, such as: Aluminum, Brass, Steel, Titanium, Magnesium, Molybdenum, Monel, Inconel, and many more.
  • Polymers, such as: Nylon, PEEK, PFA, PTFE, PVDF, Torlon, Vespel
  • Ceramics, such as: Alumina, Zirconia, and more.

What material would be best to select?

Fastener materials are typically selected based on their mechanical properties, potential for post-fabrication treatments, cost-efficiency, and a few other considerations. However, which material would be best for your application truly depends on what you need the fastener to join and where. In critical applications that will be exposed to extreme temperatures or corrosive environments it is best to select a material that is strong, can withstand the temperatures, and has good corrosion resistance.

Aluminum

Aluminum is a very popular and affordable material choice that provides manufacturers with a lot of versatility. Alone it is a great choice for lightweight, lower strength, applications that need the material to have good resistance to corrosion. If combined with other metal alloys, aluminum can have the strength of steel but with a fraction of the weight.

Brass and Bronze

Brass, an alloy of copper and zinc, is the most common copper based alloy used to manufacture fasteners. It provides decent resistance to corrosion, is relatively inexpensive, and has good electrical conductivity properties. Bronze, an alloy of tin and copper, boasts very high corrosion resistance. Both of these offer an attractive reddish-yellow color.

Steel

Steel is a popular fastener metal and comes in a wide variety of forms and strengths such as alloy steel, carbon steel, stainless steel, and many more. The corrosion resistance properties and mechanical strength of steel makes the material incredibly desirable for fasteners. The mechanical strengths range from approximately 50ksi (kilo-pound per square inch) to up to 300ksi.

Titanium

Titanium is one of the best choices for fastener manufacture, especially for high impact applications. It provides low weight, a high level of strength, as well as incredible resistance to both corrosion and wear.

Polymers

Engineered Polymers offer unique properties for specialty applications. Their temperature limits typically range from 100° C to just under 600° C. They also provide good corrosion resistance and offer decent tensile strength.

Ceramics

Few materials can withstand heat, pressure, and corrosion better than ceramics. However, they are not typically very strong; over-torque them a tiny bit and they will shatter. This makes them tricky to initially install which turns most people away from them.

Here is a quick reference table of the most commonly used fastener materials and their most noteable properties:

AluminumBrass or BronzeTitaniumNylon
-Light -Soft -Corrosion resistant-Relatively soft -Corrosion resistant -Electrically conductive -Aesthetically pleasing-Superior strength -Extremely corrosion resistant -Ideal for high-temp. environments-One of the most commonly used plastics -Exceptional strength -Excellent wear resistance
Steel – AlloysSteel – CarbonSteel – StainlessCeramics
-High strength -Low corrosion resistance -Often brittle or rigid -Often requires additional coating-Grades 2, 5, and 8 are standard for bolts and screws-Superior strength -High corrosion resistance  -Good strength -Extremely corrosion resistant -Survive extremely high temperatures -Non conductive -Non magnetic -Lightweight -Reuseable

Even the smallest component can ruin the effectiveness of a product or cause significant challenges, which in turn may determine a manufacturer’s success or failure. By partnering with experts like us in engineering and supply, manufacturers not only solve potential issues before they arise, but also boost safety, quality, speed to market, and profitability.

How can UC Components help you?

While the right materials, coating, plating, or finishing treatment for your fastener application is best defined by your process engineer, we are always here to assist you. UC Components, Inc. has been the world leader in high vacuum hardware since 1974.

UC Components, Inc.’s RediVac® fasteners, washers, nuts, and O-rings are designed for use in a wide range of high vacuum applications and clean-critical environments. We offer a variety of specialized venting designs, complete custom product development, numerous finishes, and Class 100/ISO Class 5 Cleanroom cleaning and packaging.

Contact UC Components, Inc. to learn more or to request a quote today.

www.uccomponents.com  

More To Explore

RediVac® vented fasteners
Fasteners

Can I reuse a screw?

Recycling and reusing items is something we all strive to do but can you reuse a screw? Typically you can if the screw has never

Talk to an Expert Now!
408-782-1929 Get Custom Quote