Fastening screws have lots of choices available to choose from when selecting the appropriate fastening screw for your requirements and project. Different screws are produced in many sizes and shapes as well as in different materials with different applications, so it is important to be informed about the basics of your options prior to deciding on the right fastener for your application. In this article, we will be explaining the most widely-used types of fastening screws, their applications, and some tips and tricks to help select the most appropriate fastening screws based on what you need.
What Is A Fastening Screw?
Fastening screws are a general-purpose-fastening device that can be used to hold together two different types of material or to attach similar types of material. In order for a fastening screw to work properly, it typically has a thread that wraps around a cylinder, allowing it to grip tightly and evenly into the two neighboring pieces of material. A fastening screw may be designed for any type of fastening application, ranging from wood fastening to metal fastening to fastening of electronic components. Fastening screw types can be further characterized by head type, drive type, thread form, and the type of material from which the fastening screw is made. We will discuss each of these characteristics in greater detail to assist you in making a well-informed decision in selecting the right fastening screws for your application.
Type of Fastening Screw You Can Rather Expect To See In Stores
Fastening screws will come in numerous sizes, designs, and types. The following describes the principal types of fastening screws:
1. Wood Screws
Wood screws are types of fastening screws that are manufactured with both coarse threads and pointed tips so as to securely grip a piece of softwood or hardwood without splitting it. Therefore, wood screws are primarily used for securing two pieces of wood together. Some examples of applications where the wood screw may be used include furniture assembly as well as the installation of decking and other types of carpentry work.
2. Machine Screws
Machine screws are fastening screws that are fully threaded throughout their entire length and are used to connect two pieces of metal together and any application that involves connecting metal parts would use machine screws. In addition to using machine screws directly with each other, machine screws, by nature, are designed to only attach metallic parts to one another through the use of pre-threaded countersink holes or nuts will both be required. Automotive repairs, the manufacturing of machinery, and electronic appliances are all applications that could be made with machine screws.
3. Sheet Metal Screws
Sheet metal screws can be used on all types of materials. Their sharp, self-tapping thread allows the screw to cut into thin sheets such as metal, plastic and other substrates. They are ideal for use in a variety of applications such as duct work, roofing and at home on projects like hanging lights, or HVAC work.
4. Self-Drilling Screws
In general, self-drilling (or Self-tapping) screws eliminate the need to pre-drill/ drill a pilot hole. This is accomplished as these screws have a sharp point that drills into both metal and wood surfaces. These types of fasteners are commonly found in construction and industrial applications since they save time in production and simplify installation methods by eliminating the need for pilot holes.
5. Drywall Screws
Drywall screws may be defined as a screw used to fasten drywall panels to either metal studs or wooden studs. Drywall screws will have either coarse threads for wood studs or fine threads for metal studs. Drywall screws will have bugle heads, so when driven into the drywall panel, they will be flush with the surface of the drywall panel, allowing a smooth finish.
6. Lag Screws
Lag screws (or lag bolts) are some of the strongest fasteners available in the fastener category. They are typically used for fastening heavy items, wooden beams or wooden posts to other wooden structural members (structures). Lag screws have thick, coarse threads and a hex-shaped head to provide additional strength for these load bearing applications.
7. Concrete Screws
Concrete screws, sometimes called masonry screws, are designed to attach materials to concrete, brick or stone. Concrete screws have a threaded body that will grip tightly inside a pre-drilled hole to provide a permanent, secure hold.
Fastener Screw Size Chart
When choosing a fastener screw, it is important to know what the size of the screw will be. The screw size will be determined by several characteristics including the diameter, length, thread pitch, and head size of each screw. For those searching for answers we’ve created a reference guide that contains common fastener screw sizes and applications:
| Size | Description | Applications |
| M4 | 4mm diameter fine thread | Light weight items, small electronic equipment, furniture assembly |
| M6 | 6mm diameter medium thread | Most common use is for household furniture assembly (e.g., kitchen cabinetry), brackets and some small machinery |
| M8 | 8mm diameter higher tensile strength | Medium duty fastening of medium sized beams. |
| M10 | 10mm diameter commonly used construction fastener | Attachment of the most heavy structural components and machinery to framework |
| M12 | 12mm diameter heavy duty fastener | Industrial applications with high load bearings. |
| M16 | 16mm diameter exceptional strength | Supports large structural elements and applications that carry intense loads. |
The labels M4, M6, and M10 refer to metric fasteners where the letter M indicates it is a metric fastener and the number identifies the approximate diameter (in mm) of said fasteners. Make sure to match the nominal diameter and threads per inch of the chosen fastener(s) with your project(s) when selecting a screw.
Choosing the Correct Fastener Screw Material
The material your fastener screw is made from will be a factor in performance of the fastener depending on the application of the fastener:
- Steel Screws: Steel screws are very strong and have a wide range of uses. Steel screws are only rust-able if they don’t have a coating or are only made from stainless steel. Steel is probably the most common material for fastening in construction.
- Stainless Steel Fasteners: Stainless fasteners have high resistance to both rust and corrosion. Ideal for use outdoors, in salt water (marine), or in wet areas.
- Brass Fasteners: Very resistant to corrosion, therefore suitable for marine uses as well as decorative.
- Aluminum Fasteners: Light-weight fasteners that are also resistant to corrosion; an excellent choice where weight is a factor.
When selecting the type of screw to use, it is very important to use the right type of screw to ensure long-lasting results and the integrity of both materials.
How to Use Fastening Screws Correctly
Although using a screw may seem fairly simple, if you follow these guidelines you will get the best results and avoid many of the very typical mistakes people make when using fastening screws:
Drill Pilot Holes: With many types of screws (most wood and metal screws), drilling a pilot hole will make it easier to install the screw and will decrease the chance of splitting or cracking the material.
Use The Correct Tools: Use the correct type of driver/screwdriver or drill bit to match the type of drive head on your screw (e.g., Phillips, flathead, or Torx).
Tighten With Care: Overtightening screws can strip the screw threads and/or damage the materials that the screw is fastened into.
Follow Material Guidelines: Use screws made of the appropriate material for the type of environment in which you intend to use them (for example, stainless steel screws should be used to fasten materials in moist environments).
Frequently Asked Questions
What is M8, M10, M12?
These are common metric screw sizes used worldwide. The letter “M” refers to the metric system, while the accompanying number signifies the nominal diameter of a given screw in millimeters (example: an M8 screw has an 8mm diameter). Additionally, some project specifications may indicate a specific thread pitch (for instance: M8x1.25 indicates that there are 1.25mm between each thread).
How do I measure fastener screws?
When measuring a fastener screw, three dimensions must be taken into account: length, diameter and thread pitch. To measure length, measure from the tip of the screw to the location on which the head of the screw rests. To measure diameter, measure the diameter of the threaded portion. Last, to measure thread pitch, use a caliper to measure the distance between adjacent threads. Calipers are helpful for accurately measuring all three dimensions.
What is the best type of fastener screw to use for applications in which metal joins to metal?
The most appropriate type of fastener screw or machine screw to use for applications where one piece of metal connects to another is a metal fastener screw or machine screw. Ensure that the threads on the fastener screw are appropriate for the thickness of the metal you are fastening together. If possible, choose fastener screws made from stainless steel or zinc-plated steel to reduce the risk of corrosion between the two joined pieces of metal.
Are wood screws compatible with metal?
Wood screws are specifically designed to work with wood, and therefore, should not be used with metal or any other type of surface classified as hard. In all metal applications, it is best to use fastener metal screws or machine screws designed specifically for use on metal surfaces.
Understanding the various types of fasteners screws, including their different sizes and materials, will provide you with the knowledge required to successfully complete any given project. From wood screws to machine metal screws (M4 through M16), choosing an appropriate screw for any given application results in a stable, durable and professional finish. I hope the information in this guide has equipped you to make informed decisions regarding the selection of your next project using fastener screws. Following these suggestions will help ensure that you have the information needed to be successful using fasteners for your next project!
