A screw is an externally threaded fastener. Its application is to align and hold two or more components. Depending on the types of screws, we can use them either on threaded parts or create threads on their own.
We require Screwdrivers or special tools to install screws. This guide covers various types of screws and their applications. It will help in selection of the best types of screws for your application. We suggest you read this article on the difference between screw and bolt.
Manufacturers
Screw Description
As shown in the example below, Just by looking at the screw description, we can tell what type of screw it is.
Screw Description: M3 X 10 Flat Slotted Head, Stainless, Black Anodized Machine Screw
The above screw description provides the following information about the screw.
- Screw Type: Machine
- Threads Type: M3
- Screw Length: 10 mm
- Head Type: Flat Head
- Drive Type: Slotted
- Finish: Black Anodized
- Material: Stainless Steel
Types of Screw
- Screw Types According to Its Application
- Sheet Metal Screws
- Machine Screws
- Set Screws
- Wooden Screws
- Thread Forming Screws For Plastics
- Security Screw
- According to Screwdriver Types
- Slotted Screw Drive
- Phillip Head Drive
- Frearson Drive
- Torex Drive
- Robertson or Square Drive
- Hex Socket or Allen Drive
- Types of Screw Head
- Flat Head Type
- Pan Head
- Truss Head
- Socket Head Cap
- Hex Head
- Round Head
- Button Head
- Oval Head
- Type of Screw Thread
Types of Screws According to their Application
The following types of screws are available in the market according to the application of the screw.
Sheet Metal Screws
Sheet metal screws are pointed tip, thread cutting types of screws. They cut threads and join sheet metal parts.
Sometimes sheet metal screws are also used in wooden or plastic parts. But they are preliminarily designed to be used in sheet metal parts. We require a pilot hole in sheet metal parts to position self-tapping screws.
Machine Screw
Machine screws have a uniform diameter in the entire length and require machine threads in one of the parts that we are screwing.
As the name suggests, a machine screws design is to join machine parts. But these days, they are widely used in products machines, consumer electronics, and home appliances such as laptops, mobiles, kitchenware, etc.
Set Screw
Set screws or grub screws are a type of screw without a screw head or any protrusion beyond the screw diameter.
They have applications where:
- The screw head should not protrude outside the product.
- Small space is available for the screw head.
For example, grub screws application is to assemble the shaft and gear because using another type of screw can hinder the gear operation.
Wooden Screw
Wooden screws are available in steel or brass material, not wood. They have a sharp point that can pierce into the wooden part.
Thread Forming Screws for Plastic
Thread-Forming screws are different from self-tapping screws used in the sheet metal industry. Self-tapping screws create screw joints by cutting the plastic material. Whereas thread forming screws creates screw joints by forming the threads in plastic material.
Security Screw
Security screws are types of screws with rarely used screw drive types. They have applications where the requirement is open the product with specific tools only.
Security screws don’t work similarly to a lock. They provide only a certain level of protection.
For example, some consumer electronics products use security screws to screw top and bottom housing to ensure customers don’t open the product. Therefore companies can manage the product warranties and saves the product from getting damaged.
Type of Screws according to the type of Screw-drive
The selection of the type of screw drive depends on product application. For example, unidirectional head screws have applications in products where parts are not supposed to disassemble. Therefore unidirectional screws work as security screws as well.
The following types of screw-head drives are widely available in the market.
Slotted Screw Drive
The slotted type of screw drive is the oldest and widely used screw drive. Therefore the slotted head type of screws is recommended
- In DIY kits.
- In applications where users need to tighten or lose the screws very frequently.
For example, slotted head types of screws have applications on wall mounts, kitchenware products, handles, etc.
Phillips head Drive
Phillip-head screw drive is one of the widely used screw drives. The manufacturer recommends Phillip-head screws on the production line because of the following advantages.
- In Phillip-head screw drives, the operator does not need to align the screwdriver position. It improves overall productivity.
- The screwdriver slips from the Phillip-head when excessive torque is applied.
Frearson Drive
Frearson screw drive, reed, or Prince screw drive is similar to a Phillips head screw. These screw drives have the advantage of using one screwdriver for multiple screw sizes.
Torx Drive
A Torx drive has 6 points star shape and is used to transmit high torques without damaging the screw head. They also provide security to a product because engineers rarely use Torx drives in products.
Torx screws have applications in automobiles, bicycles, and miniature products such as watches, smart phones or laptops, etc.
Robertson or Square Drive
Square drive/ Robertson Phillips combination drives have applications in the wooden & construction industry, electrical products, terminals, and connectors.
Hex Socket or Allen Drive
Hex Socket or Allen head screws have applications to transmit high torques where the screw is not accessible from the top.
Allen keys can tighten Allen screws even when we do not have direct access to the screw.
Screw Head Types
Following types of screws with different head types are available in the market. Each head type has its application.
Flat or Countersunk Screws
Countersunk or Flat types of screws have a flat outer face and tapered inner head face at an angle of 90° or 120º. They have applications where:
- A screw head should not protrude out
- Limited material thickness is available to accommodate the screw head.
Pan Head Screws
Pan head screws are the most widely used type of screw head in wooden, sheet metal, machine, and thread forming screws. These screws’ top surfaces have a slight dome shape.
Truss Head Screw
These types of screws comparatively have larger screw head diameters and smaller heights. They provide a larger surface area on the parts to be jointed. Therefore this head type is generally used to assembly thin and soft materials.
Socket Cap Head Screw
A socket head cap screw is a type of screw with a cylindrical head and Allen drive.
They have applications where limited direct access to the screw is available. For example, 90º Allen Keys are used to tight socket head cap screws.
Hex Head Screw
The hex head is generally used with large size screws or with bolts. They have applications in the wooden, construction, and heavy metal industries.
Round Head Screw
Round-head types of screws have a round-shaped head. They don’t have any special applications. But they preferred when the screw head is exposed to the user.
Button Head Screw
The screw button head is designed like this to accommodate hexagonal or Allen drive slots. Compared to socket cap head screws, they have a smaller head height.
Oval Head Screw
Similar to flat head CSK screws, Oval head screws have tapered bottom and oval top. They have applications where CSK screws shall have an aesthetic finish as well.
We will keep adding more information on different types of screws and their applications. Add your suggestions, comments, or questions on different types of screws in the comment box.
We suggest you also read this article on various types of screwdrivers.
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