Ribbed Neck Carriage Bolts

Introduction

Ribbed-neck bolts, a type of carriage bolts, are examples of commonly used fasteners. Bolts are generally used in fastening several materials together. A wide variety of bolts are in existence today each with its set of benefits, areas of application and properties. The carriage bolts, which are of focus in this article, is one type of fastener and is commonly referred to as coach bolts. So, what are the carriage bolts? 

Carriage Bolts

These are types of bolts designed explicitly for use in the construction of wooden products. In the early 1800s, these bolts were employed in constructing carriages as well as their wheels hence their name. Just like other bolts, the carriage fasteners come in various styles defined by their distinct neck and head shapes. The following are the types of carriage bolts used today:

1.    Ribbed-neck round head; these carriage bolts are the primary focus of the article. They are usually made out of low-carbon steel and are characterized by the fact that each of them has a ribbed or serrated shoulder aside from the round head they feature. The application of these types of fasteners includes binding soft, ductile metals, wood, and plastics.

2.    Round head-short neck; these bolts, just as the name suggests, comprise of a round head on top of small square-shaped shoulder. One of their unique traits is that they have a unified thread pitch and since they are made out of low or medium-carbon steel, they can be used with sheet metal. This is as opposed to using standard neck-sized bolts which could create an obstruction.

3.    Flat head-square neck; these fasteners feature a flat head that allows them to keep a low profile either at the top or front side of a surface compared to rounded bolts. For this reason, these bolts are especially suited for but not limited to the garage door industry.

4.    Fin neck; this type of bolts are also made out of low carbon steel and comprise of a rounded head coupled with a flat bearing surface. The presence of this bearing surface allows for a ninety-degree angle with the shank which makes them uniquely perfect for use with thin plywood.

Now that you have all this background information regarding the carriage bolts, it is time to understand more about the ribbed-neck carriage fasteners. These bolts have round head as well as a flat bearing surface that intersects with the shaft at ninety degrees. On the other hand, where the shank and the bearing surface meet, ribbed fins emerge. The purpose of these ribs on the neck of these fasteners is to prevent the bolt from moving once it has been set in a substrate during the assembly of the nut. This type of ribbed bolt comes in three types as well which are discussed below.

Low-Carbon Steel

These ribbed-neck carriage bolts can be described as round-headed fasteners containing a square neck underneath as well as a unified thread pitch. They are usually manufactured from low-carbon steel which provides it with a tensile strength of 60,000 psi minimum and a yield strength of 36,000 psi minimum. The purpose of the square neck is to prevent the bolt from turning during the tightening of the nut. This, in turn, allows for a much tight bind between two or more materials.

 Low carbon steel ribbed neck carriage bolts also come in two types.

The fully threaded zinc which is manufactured in line with the ASME B18.5 specifications. These fasteners offer a tensile strength of 60,000 psi. Being fully threaded provides the bolt with significant stability while it is being fastened. The purpose of the zinc plating is to protect the bolt from corrosion during harsh conditions. Zinc material has proven itself in the automotive industry where it is often plated on parts such as transmission components and the braking system to prevent corrosion. As such, it plays a similar function for these bolts guaranteeing long-term security.

Partially-threaded zinc- this fastener offers similar strength to its counterpart above (60,000 psi) as is manufactured following the ASME 18.5 specifications. Its partial threading plays a similar role of ensuring stability during the fastening of the bolt. The zinc plating is also meant to protect it from corrosion.

18-8 Stainless Ribbed-Neck Carriage Bolts

This fastener can be described as a carriage bolt which has a round head on a square neck complemented by a unified pitch. It is manufactured out of austenitic allow stainless steel which provides this ribbed neck carriage bolt with similar design advantages to the low carbon steel bolts. However, its primary advantage over the other carriage bolts is the fact that its design allows it to withstand environments that demand a general resistance to atmospheric corrosion. This characteristic makes this type of bolt particularly useful for designing products that are to be exposed to harsh environmental conditions.

This is because their low susceptibility to corrosion will allow for the bolt to maintain its tensile strength and hold the product together until repairs can be done. These ribbed neck carriage bolts derive their strength from their manufacturing process. The alloy gains its strength through a process called work hardening conducted during the manufacturing of the fastener. This process involves a heat treatment to which the austenitic stainless steel is susceptible called annealing. It occurs at approximately 1900 degrees Fahrenheit which transforms the alloy into a dead-soft condition that is thermally irreversible.

Grade-5 Steel

The ribbed-neck carriage bolts in this category are manufactured from medium-carbon steel which is usually subjected to heat treatment. Their manufacturing process entails heat treatment at a minimum temperature of about 800 degrees Fahrenheit. This results in the creation of a bolt with tensile strengths equating to 120,000 psi minimum as well as a yield strength of 92,000 psi minimum. As a result, the application of these ribbed neck carriage bolts is similar to their low-carbon counterparts. However, they offer a higher loading capacity because of their higher tensile and yield strength.

In conclusion, it is crucial that you understand exactly what you need before going ahead to purchase it. Failure to know the miniature but significant differences between existing fasteners could have a significant adverse outcome on what you intend to create. Carriage bolts are of several types each with unique properties. This exclusivity of these products makes them suitable for certain specific conditions. For instance, if you use low-carbon steel bolts, it is crucial to know its strength so that you may avoid overloading the vehicle that you create. A final word of caution is that you should purchase these products from qualified manufacturers to prevent being given fasteners of sub-standard quality.

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Created on Oct 8th 2018 08:55. Viewed 255 times.

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