Most Common Types of Screws and Bolts
Although screws and bolts may get confused for one another with their somewhat similar functions and appearance, they are structurally and functionally different. Recognizing how they engage with materials, the tools required for their installation, and their most notable subtypes is essential for selecting the right fastener, whether you are tackling a DIY project or managing complex industrial assemblies. In this guide, we will go over the fundamental differences between screws and bolts, briefly exploring commonly used variants to help you make informed fastening decisions.
The Basic Differences Between Screws and Bolts
|
|
Screws |
Bolts |
|
Threading |
Have full or partial helical threads to form threads in the material |
Typically partially threaded |
|
Fastening Method |
Self-tapping or self-drilling into the material |
Inserted through pre-drilled holes and usually secured with a nut |
|
Holding Strength |
Usually fit for softer materials, though some variants can be used in more heavy-duty tasks |
Greater tensile strength for high-load or structural applications |
|
Installation Method |
Placed with screwdrivers or drills |
Tightened with wrenches or sockets |
|
Reusability |
Not directly intended for repeated use, but can be in some instances |
Often designed for repeated assembly and disassembly without significant wear |
Popular Screws
Self-Drilling Screws
With hardened, drill-shaped points and threads engineered for strong holding power in thin or layered materials, self-drilling screws can cut their own pilot hole during installation. This feature reduces labor time in applications such as sheet metal fabrication, HVAC installation, and steel framing.
Machine Screws
Machine screws are made to join metal parts that require repeatable disassembly and reassembly without damaging internal threads, relying on pre-formed internal threads in the receiving material. With uniform threading and availability in various head shapes, sizes, and materials, they serve a vast array of electronic devices, appliances, and mechanical assemblies.
Socket-Head Screws
Socket head cap screws can be installed flush or below the surface of a component, making them ideal for assemblies where clearance is limited or a clean, precise finish is desired. Characterized by a cylindrical head and a recessed hexagonal drive, they have excellent clamping force and high load-bearing capacity.
Set Screws
Fully threaded along the shaft, set screws are specifically designed to secure one component within or against another without protruding above the surface. These screws are effective for applications where minimal clearance and flush mounting are needed, relying on internal pressure applied to a pre-threaded hole pressed directly against a mating part.
Notable Variants
- Cup Point: With a concave tip that digs slightly into the shaft surface, cup point set screws offer great holding power for permanent or semi-permanent assemblies where some shaft marring is acceptable.
- Knurled Cup: Similar to the cup point but with serrations or knurling on the tip, these set screws increase holding friction under vibration or dynamic loads.
- Flat Point: Flat point set screws have a flat tip that rests against the surface without causing indentation, enabling repositioning or adjustment of the secured part without damaging the shaft.
Popular Bolts
Shoulder Bolts
Shoulder bolts, also known as stripper bolts, contain an unthreaded cylindrical shoulder between the bolt head and threaded portion. This shoulder allows for smooth movement of attached components while staying locked in place, so they are often employed as pivot points, guides, or axles in machinery.
Hanger Bolts
Containing wood screw threads on one end and machine screw threads on the other, hanger bolts are dual-threaded to create secure connections between wood and metal components. The wood-threaded portion is embedded into timber or composite surfaces, leaving the machine-threaded section exposed to receive a nut or threaded fitting. As a result, hanger bolts are found in furniture assemblies, overhead hanging systems, mounting fixtures, and other scenarios where these materials must be matched.
Carriage Bolts
Carriage bolts have a rounded, dome-shaped head with a square neck directly beneath it. Once one is inserted into a hole in a wood assembly, it grips the material to prevent the bolt from turning during tightening. Creating smooth, tamper-resistant finishes, carriage bolts are widely used in deck construction, fencing, timber-to-metal joins, and outdoor furniture for both durability and a clean aesthetic.
Eye Bolts
Eye bolts feature a loop or "eye" at one end for reliable attachment points in tension-bearing lifting, rigging, and anchoring applications.
Notable Variants
- Plain Pattern: With a simple, unreinforced eye, this type of eye bolt is intended exclusively for straight, vertical loading applications where no lateral or angular force is applied.
- Shoulder Pattern: Incorporating a widened, machined shoulder between the eye and the threaded shank, shoulder pattern eye bolts are more strong and stable for applications involving angular or side loading.
ASAP Distribution: A One-Stop Source for Screws and Bolts
Those seeking screws or bolts of any type should always rely on a dependable distributor to ensure they can secure high-quality options that match their intended application. ASAP Semiconductor is proud to offer customers access to thousands of high-quality fasteners from leading manufacturers and suppliers across the globe through our purchasing platform, ASAP Distribution.
With a search engine and various organized catalogs for you to browse by part number, part type, manufacturer, and more, we make it simple to track down all that you need on this website. Moreover, when you kick off procurement with us, our expert team will work with you to meet all of your specifications with competitive, timely solutions. To see how else we can serve your operations, explore our selection and connect with us by phone or email at your convenience.
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