Virtually every mechanical assembly designed in industry makes use of fasteners to attach components together to form systems.

Fastener failures (due to improper design/selection or installation) are THE NUMBER ONE cause of mechanical failures in industry.  The topic is rarely given the focus it deserves in the classroom for a variety of reasons, none of which are acceptable. 

Selection of the correct Fastener is very important. Cost of the fastener is always insignificant compared to maintenance and liability costs resulting from joint failure.

Begin by assessing the load that will be placed on it. Any metal fastener will hold well against a sideways (shear) force. But with a tensile force pulling the fastener straight out, holding strength becomes increasingly dependent on the threads (or formed head in the case of rivets) holding the fastener in place. The load on lifting and towing eyes is almost entirely tensile — it is trying to stretch the fasteners or pull them from their holes. 

The right fastener and proper installation methods keep bolted joints from loosening.

Fastener Selection Guide

Fastener Materials

Fasteners can be made from many materials, but most are made of carbon steel, alloy steel, or stainless steel. Stainless steels include both iron- and nickel-based chromium alloys. Aluminium has become an important material recently because of low weight and cost. Brass and Plastics are also used in specific applications.

Titanium Alloys have limited usage, primarily in the aerospace industry.

Using Stainless Steel Fasteners

There are many  Reasons to use Stainless Steel Fasteners
Corrosion Resistance
Cosmetically Appealing
Largely Non-Magnetic 
Reasonably Inexpensive
ROHS Compliant

Stainless Steel Fasteners are, most importantly, corrosion resistant. They have an excellent life cycle, are environmentally friendly and are 100% Recyclable. They are also resistant to high heat as well as extremely cold temperatures making stainless steel fasteners the material of choice for almost any application! 

There are many different grades of stainless steel. The two commonly used grades are 304 and 316, with 316 being more corrosion resistant than 304.

Stainless steel resists corrosion due to it’s naturally occurring protective layer (‘Chromium Oxide’). When contaminants settle on stainless steel, depending on the grade and the surface finish, these can damage this protective layer, allowing oxygen to react with the iron in the stainless steel causing it to rust. Therefore, if stainless steel is going to be exposed to contaminants in a corrosive environment, then consider options to enhance the corrosion resistance: select a more corrosion resistant grade