Episode 4 – What Makes A Bolt So Great?

Advantages of Bolts

There are many advantages to these kinds of fasteners. First, bolts have very low production costs. Second, bolts and nuts are both easier to install and easier to replace than other assemblies, like welded fasteners. Third, it’s easier to inspect bolts that are fastened in with nuts, rather than bolts that are welded in. The latter sometimes requires time consuming and costly inspection with an x-ray machine, whereas the former can usually be inspected with the naked eye. Finally, bolts and nuts create consistent bonds. Although they are used almost everywhere, the most common places to utilize these fasteners is in industrial manufacturing, aerospace, automobiles, transportation, and construction.

Bolt Design

Production Process

The manufacturing process used to create standard metal bolts takes many steps. First, manufacturers heat a wire rod in a furnace for 30 hours, then bathe it in sulfuric acid to remove any rust particles. Then they usually coat it with phosphate for rust resistance and lubrication. This concludes the pre-treating process.

After this, manufacturers form the rods via cold forming. During this process, they use high pressure and long, round dies to shape the rod at room temperature. After the rod comes out of the dies, manufacturers cut it into shorter pieces and feed the pieces into another die; this die shapes their heads.

The last step is threading. To thread the bolts, manufacturers send them through high pressure rollers that press in the thread pattern.

Material Design

The materials used to manufacture industrial bolts include aluminum, brass, copper alloys, plastics, steel, stainless steel, and titanium.

Each offers something different. Aluminum, for example, is used for making light industrial bolts that are electrically conductive and resistant to corrosion and thermal energy. Brass, on the other hand, makes bolts with low magnetic permeability and oxidation resistance. Copper offers good wear resistance. Plastic offers excellent water resistance with light loads, while stainless steel fastener types are chemical and corrosion resistant.

Design Aspects

When designing bolts, bolt manufacturers think about a variety of different design aspects. These include: the major diameter of the external thread, pitch measurement (distance from one ridge, or crest, of one thread to another crest), helix angle (the slope of the thread) and thread angle (V-shaped angle between the crest, formed by threads).

Customization

For your unique task, bolt manufacturers can create any number of custom fastener designs. They can vary them in many ways, including: material, head type, head mark, screw grade, and characteristics like tensile strength. They can also fabricate them with fine or coarse threads; coarse thread bolts are most common for general applications. For added durability, manufacturers can coat bolts with corrosion resistant layers.

Parts of a Bolt

Head of a Bolt

The head acts as a mount where tools, based on the operation, either apply or resist torque. It also functions as a bearing surface that holds the substrate from one side.

Different industrial bolts have different types of heads, including, square shouldered head, indented hexagonal head, hexagonal washer head, trimmed hexagon head, and flanged hexagonal head.

A square-shouldered head has a truss head on a square shank that is especially designed to resist the motion. Indented hexagon heads are designed in conjunction with standard wrench dimensions and have a depression on the head. As the name implies, a hexagonal washer head has a built-in washer, which protects the assembly from disfigurement during installation. Trimmed hexagon heads are found in a standard bolt; it has clean and sharp corners.

Bolt Shank

The shank is the shaft of the bolt on which helical threads are made externally. It is the longest part of a bolt and aligns the components when they are fastened.

Bolt Chamfer

The chamfer is the end of a bolt where the nut is fastened. The chamfer is slightly beveled, so that insertion of the bolt into the hole of the nut is easier.

You might think by now that you’re halfway to a mechanical engineering degree, but it’s important to know the technical side in order to determine what needs protection and why. At its most basic form, after all the design and engineering has been done, the right materials selected and the bolt has been manufactured properly, wouldn’t it be a shame if you didn’t protect it on its journey to your customer?  Eagle Pride Supply offers protective mesh netting for that exact purpose. 

Its not flashy or filled with lots of bells and whistles, but protection is what you’re after, and these really do the job well!