Different Types of Bolts

Bolts are some of the most important fastening tools used in practically every industry today. Man has used bolts throughout history for a wide range of applications. Bolts are commonly made of iron and steel, though wood and even plastic have been used in some applications. The current trend in bolt manufacturing today is that manufacturers design fewer bolts that can be used for multiple applications. Bolts are commonly identified by the shape of head such as hex bolts, dome bolts, eye bolts and many others

Hex Bolts

Hexagonal screw hard bolts, or simply hex bolts or machine bolts, have a hexagonal head and are the most commonly used bolts in the construction and repair industry. Hex bolts are available in a wide range of diameters and sizes. Hex bolts are made of different types of materials namely:

  • Stainless Steel Bolts: Stainless steel bolts are high-strength that do not require an anti-corrosion coating.
  • Alloy Steel Bolts: Alloy steel bolts are heavy-duty hex bolts designed for applications that require very high strength. They are coated with zinc or cadmium to prevent corrosion.
  • Carbon Steel Bolts: These are the most common hex bolts. They are used for normal applications and are coated with zinc to make them corrosion-resistant.

Hex bolts are used in automotive, coastal, marine, and high temperature environments.

Dome Bolts

As the name suggests, dome bolts sport a dome-shaped head. There are several types of dome head bolts including:

  • Dome-Hexagon Head: These types of bolts have a dome at the top part of the head while the lower part is hexagonal-shaped. They are often used on earthmoving equipment as retaining bolts, and are sometimes used to fasten engine heads.
  • Titanium Dome Bolts: Titanium dome-shaped bolts are specialised high-strength bolts made of titanium. They have excellent anti-corrosive properties, and are non-magnetic. They are commonly used in the chemical industry, aerospace or military industry, medical field, automotive industry, and the petrochemical industry.
  • Anti-Theft Bolts: Dome-shaped anti-theft bolts are used in railway lines for fastening joint bars, turnouts and other railway systems. They are usually treated with oil to prevent corrosion.


Unlike other bolts, eyebolts sport circular rings instead of wrench heads. The circular rings are used for attaching chains or ropes. The threaded end of an eyebolt is pointed and can be directly screwed on surfaces like wood with no need to use a threaded nut. Eyebolts are used to hang heavy fixtures such as storage containers or lighted ceiling units. Forged eye bolts are the strongest eye bolts. These are one-piece eyebolts that can bear very heavy loads. This type of eyebolt is used with a nut that is firmly anchored to a metal or wood surface. Forged eyebolts are frequently used in the manufacturing and construction industries, but can also be used at home in applications such as lifting heavy hammocks.

Chemical Anchors

Chemical anchors are bolts that are bonded onto a substrate such as concrete and masonry, using resin-based adhesives. Chemical anchors are perfectly suited for high-load applications. Chemical anchors work on the principle of gluing or chemical adhesion so that the load stress is not transmitted to the base material. This makes Chemical anchors ideal for fixing close to the edge, group anchoring or in closes spaces where the base material is not strong enough to support the load.

Sleeve Anchors

Sleeve Anchors are used as expansion bolts in masonry or concrete. Sleeve Anchors are made of a centre core bolts coupled to an expansion cone at the opposite end and surrounded by a full-length sleeve. Tightening the head of and Sleeve Anchors makes the cone expand and provide grip. The good thing about Sleeve Anchors is that their grip is evenly distributed throughout their entire length instead of just at the tips, making it ideal to use in weaker material such as sandstone and brick.

There is a bolt designed for almost any kind of application you can think of. While a little research is necessary to get the right info, author Erin Warbrook spoke to Konnect Shop for her info on nuts and bolts.