Philips, Slotted, Allen a. Socket , Frearson similar to Philips , etc. Head Style Many categories are also available with different head shapes or styles.
For help identifying different fastener head styles see our Fastener Type Chart. Flat head, Pan head, Truss head, etc. Fastener material describes the material from which the fastener was made as well as any material grade. For help identifying different fastener materials please see our About Fastener Materials and Grades page.
As you can see, the thread pitch of the coarse metric bolt is much finer than a coarse thread standard bolt. The two on the right are stainless steel, while the one on the left is zinc plated. A questions for the ages, sometimes people get them mixed up. A bolt usually has a flat tip and is built to work with a matching nut, and is engineered to be torqued by the nut. A machine screw is actually closer to a bolt than a screw.
A machine screw threads into a nut or an insert, but unlike a bolt, it is meant to be tighted by the head of the machine screw.
So to clarify; a screw makes its own threads and torque is applied to the head; a machine screw needs something to be threaded into, and torque is also applied to the head; a bolt is designed to be tightened by the nut.
The picture below is a great example of head types but, tamper proof heads are always being created for obvious reasons. Some heads get stripped easier than others, for example the double hex below. The following image was taken from the back cover of the Papco catalogue, and is a good example of how different heads are shaped.
It really all comes down to the application. How strong is that bolt? In the case of hex head bolts, most of them come with markings. Metric bolts have numbers, standard bolts have little lines, and rusty bolts… good luck. Tensile strength is is the maximum amount of stress a bolt can endure from being stretched or pulled until it fails. Again this is only important when it comes to the application.
Low grade bolts are going to work for most everyday applications, like mounting a flat screen television, or keeping your chair together. The higher grade bolts are reserved for heavier machinery that really need that extra strength. What is that bolt made out of? Neodymium also known as rare Earth magnets have become increasingly popular in recent years, both We use cookies to improve your experience. By your continued use of this site you accept such use. For more information, please see our privacy policy.
Want to read the latest news from Monroe Engineering? Click Here. Skip to content. Get a Quote. Hex bolts are often used to fasten wood to wood, metal to wood, or metal to metal. Hex nuts and washers are typically used with hex bolts, the washers being valuable for situations where the material being joined is softer and may deform under the tightening force applied to the hex bolt. Hex bolts are sometimes referred to as hex cap screws when they use a washer face underneath the head and feature a chamfered end.
Hex bolts lack those features. Machine bolts are used to fasten together two pieces of material, and are similar to hex bolts, except that they will not have a chamfered point and are not designed with a washer-bearing surface on the underside of the head. They are typically available in both hex head and square head options. A different fastener product, machine screws, is often used synonymously with machine bolts which is a source of confusion.
Machine screws tend to be smaller in size than machine bolts, but usually have uniform threading along the full length of the fastener. Unlike other types of screws such as wood screws or sheet metal screws, the fasteners feature a flat tip, not a pointed or tapered tip as is common with these other types of screws.
Screws generally are designed to be used either with pre-tapped holes or to be driven into materials where the screw will create its own thread in the material as it is tightened. By contrast, bolts are designed to be tightened by applying and torquing a mating nut on the end of the bolt. So while nuts and bolts are paired fastener items, nuts are not typically used with screws which instead are threaded into pre-tapped holes.
Both machine bolts and machine screws are available in different head styles, including hex head which is frequently paired with hex nuts, as well as flat head, oval head, and cheese head, to name a few. Penta-head bolts are an example of a tamper-resistant bolt, which may be used in applications where it is desired to reduce the likelihood that a person armed with standard tools can loosen or remove the bolt. With the head of the bolt in the shape of a pentagon, standard wrench or socket sets will be incapable of being used on these bolts.
Similar in appearance to carriage bolts, round head bolts do not have the square taper beneath the domed head of the bolt and are typically used to join wood. The softer nature of wood permits the bolt to compress against the surface of the wood and grip by friction to preclude the bolt from turning when the nut is tightened. Shoulder bolts , also called stripper bolts, feature a threaded bolt section of smaller diameter than the shoulder of the bolt the section of the bolt between the head and the beginning of the threaded portion.
Shoulder bolts are useful for functioning as a shaft or axle that can contain a rotating part, such as a bearing or a bushing. Socket head bolts feature a recessed head that is tightened using an Allen wrench or hex socket tool. The head style of these bolts can vary from a cylindrical profile to a flat-head countersunk style to a domed button head design, depending on the desired use.
The deeper recessed Allen socket head affords the ability to increase the torque applied to these fasteners while minimizing the risk of stripping or damaging the head. Socket head bolts are often referred to as socket head cap screws, depending on the supplier. Square head bolts, also called square bolts, were once very commonly used predating the creation of hex head bolts.
While square bolts are still available, they are primarily used in railway applications or to achieve the aesthetic of an older or more traditional appearance.
The hex head bolt is much more commonly utilized given the prevalence of tool options such as socket sets, but many tools can still be used to tighten square head bolts. Square head bolts are available in low, medium, and high strength grades and have both a square head and T-slot head option available. Steel and stainless steel are the most common material options. Both fully and partially threaded options are available.
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