Choose the Right Fastener Material for Your Application
Choosing the best fastener material for a particular application requires analysis of several factors. Among these are the conditions under which the nuts, bolts, and screws will operate, their chemical and mechanical properties, their cost, and even their appearance. While no single material is right for every job, the characteristics of steel, stainless steel, brass, and nylon often make each the “right” choice for specific operations. This guide from Mr. Metric can help you choose the threaded fastener that will work best for your operation.
The workhorse of the fastener family, steel is ubiquitous in manufacturing and construction because it is easy to form into the various sizes, shapes, and specifications required. Steel also provides reliable strength and can be alloyed with other metals to fortify desired traits.
Adding carbon to steel makes it harder and suitable for use in various applications, but also increases the cost of manufacturing the fasteners. Using a higher grade than necessary can make processes more costly. Common Grade 2 carbon steel – the least expensive – is durable enough for most projects, striking a balance between strength and cost. More heavy-duty jobs, such as many in the automobile industry, require stronger fasteners such as Grade 5, which contains more carbon. Car suspensions and chassis may be bolted with Grade 8 carbon steel, which is stronger yet.
Stainless Steel Fasteners
Steel is one of mankind’s most important innovations, but from the beginning, its tendency to rush has been troubling. Water, salt, and other corrosives expedite the oxidation process, making carbon steel a less-than-ideal material for shipyards and other maritime industries, as well as many production operations involving chemicals, food processing, and more.
Adding 11 percent chromium creates stainless steel, preventing the formation of ugly, flaky, movement-inhibiting rust. Instead of iron oxide, stainless steel forms chromium oxide, a thin, strong surface layer that resists corrosion. By “protecting” the steel from rust, the chromium helps maintain fasteners’ strength and structural integrity. Stainless steel:
- withstands extreme heat and cold
- resists magnetism
- retains its finish
This makes stainless steel a viable material for manufacturing and construction fasteners in any environment.
When a metalworking or woodworking application is more decorative than functional, brass fasteners can be a strong choice. The alloy of copper and zinc produces an attractive gold color, and exposed screw heads nicely accent dark wood, gray metals, and other materials.
Because it is much softer and possesses less tensile strength than steel, brass’s practical uses are limited. Many of the applications for which brass bolts are well-suited are better fulfilled by stainless steel. The exceptions include jobs where non-ferrous materials are required, and use in electrical components, as both zinc and brass are strongly conductive. Brass screws also conduct heat and resist corrosion, suiting them for marine installations and around potable water and steam-driven industrial processes.
Nylon offers several properties prized by specialty manufacturers:
- Non-conductivity – Because they are non-metallic, nylon nuts, bolts, and screws do not conduct electricity. Their insulating qualities that make them popular fasteners in computers and other electronics where current isolation is necessary.
- Corrosion resistance – Nylon fasteners do not react to oxygen, so they do not rust. However, nylon is hygroscopic. In wet or humid environments the fasteners can fail due to distension from water absorption. Nylon also maintains its structural and performance integrity when used in a variety of acidic and basic solutions and when exposed to a spectrum of chemicals and solvents.
- Vibration absorption – Nylon fasteners absorb vibrations more readily than metal. This can help eliminate self-loosening of nuts in industrial machinery. Vibrating metal fasteners can cause clamped metal panels to corrode. Using nylon fasteners eliminates this concern.
- Other advantages – Nylon also is lighter than aluminum, does not burn (it melts), and can be tinted during molding and extrusion.
Call Mr. Metric today at 408-286-8816 or contact us online for help with determining which fastener material is right for your job.