A Brief Discussion on the Types of Screws
A screw is a kind of fastener, which is almost similar to a bolt but still belongs to different categories. Commonly made of metal, its unique feature is the helical ridge that strengthens the resistance against counterfeiting. There are many types of screws that are used in numerous applications where it is required to position objects or hold them together.
A screw consists of a head that features a type of recess and a body that features threads. Some of them are designed to mate with a female thread such as a nut while others are designed to be inserted in softer materials by cutting a helical groove.
The Basic Difference between Screws and Bolts
The line of difference between bolts and screws is quite vague. However, a basic concept is a bolt takes a nut on the other side after passing through an object or surface. However, a screw doesn’t take any nut as it threads directly into an object.
Besides, bolts are often sold with matching nuts, which are not typically included with screws.
Various Types of Screws
Numerous screw categories are available in the market. For ease of discussion, we’ve divided them according to the designs of their different body parts:
The Recess Design
Based on the recessed style, the screws can be divided into five types:
Torx Drive: It looks like a 6-point star-shaped pattern that is seen on velocity and high-performance multi-fix screws.
Slotted Recess: It features a linear pattern on the head. It’s the conventional recess for certain woodscrews.
Cross Recess: It looks like a crisscross of two slotted recesses. It’s normally seen on clipboard screws, wood screws, etc.
Square Recess: It is the standard design for self-drilling screws.
Philips Recess: Such a design is mainly suitable for drywall and self-drilling screws.
The Head Design
There are nine different types of screws if you take the design of head into consideration. Let’s take a look:
Countersunk Head: They are specially designed for countersinking into timber.
Double Countersunk Head: An improved version of the countersunk head screws for added strength and making countersinking easier.
Countersunk Ribbed Head: These screws come with small ribs on the countersink to make the process quicker and easier.
Raised Head Countersunk: The slightly raised dome of the head is the most suitable for using in hinges.
Bugle Head: Featuring a curved surface just below the head, these screws don’t tear or create any damage when used in plasterboard paper.
Besides, there is a flange, round, and hex head screws are available.
Design of Threads
Considering the design of the body threads, you’ll find five types of screws:
Fine Thread: Suitable for using with thick steel materials.
Coarse Thread: They are compatible with thin steel materials and all types of timber applications.
Twin Thread: Designed to be used with soft materials, they facilitate quick insertion.
Hi-Lo Thread: With an excellent holding ability, these screws are used in plastic materials and soft timbers.
Design of Point
Needle Point: You can use them to pierce maximum 0.6 mm deep without drilling into plastic, light gauge metal, MDF, and timber materials.
AB Point and B Point: Suitable for using in heavy sheet materials and shallow holes, respectively.
Type 17 Point: They can cut through thin metal sheets and timbers without the need of pre-drilling.