Classification and uses of tole screws

Classification and Application of Self-Drilling Screws

Structural Features of Self-Drilling Screws

Self-drilling screws, also known as hex lag screws, are a common type of fastener used in the construction and manufacturing industries, particularly for projects involving metal sheets and steel. These screws have a unique design that optimizes their performance and provides high efficiency. Here is a detailed breakdown of the structural features of self-drilling screws:

1. Screw Head

Design: The screw head has a hexagonal shape, allowing users to easily drive the screw securely and precisely using specialized tools.
Tip: The tip of the screw comes in two main styles, depending on the screw type:
- Self-drilling tip: This tip has a sharp fishtail shape, enabling the screw to self-drill directly into the material without the need for pre-drilled holes.
- Pilot tip: This tip has a pointed shape, and pilot holes must be created before using the screw.
Washer: Some self-drilling screws come with a washer (usually made of rubber or plastic) that serves to seal the installation point, preventing water ingress and ensuring the joint's durability.

2. Screw Shank

Design: The screw shank has a cylindrical shape with continuous threads from the head to the end. The threads can be single or double, depending on the application.
Material: The screw shank is made from high-strength and load-bearing materials such as carbon steel, stainless steel (inox), aluminum, etc.
Length: Screw lengths vary, commonly ranging from 16mm to 50mm, catering to diverse construction needs.

3. Screw Tail

Design: The screw tail can be pointed or have a drill tip, depending on the screw type.
Function: The screw tail helps the screw grip firmly into the material when driven in.

Key Features of Self-Drilling Screws

Self-drilling capability: Thanks to their self-drilling tips, self-drilling screws can easily penetrate hard materials like metal sheets and steel without the need for predrilling, saving time and labor costs.
Strong fastening: With their sharp thread design and good adhesion, self-drilling screws provide strong and durable fastening of materials.
High load capacity: Self-drilling screws are manufactured from high-strength materials, enabling them to withstand significant loads, meeting the requirements of various construction projects.
Corrosion resistance: Some self-drilling screws are made from stainless steel, offering excellent corrosion resistance, making them suitable for use in harsh environments.
Ease of use: Self-drilling screws can be easily installed using specialized tools such as power drills or hex screwdrivers.
Cost-effectiveness: Compared to other fastening methods like welding or nails, self-drilling screws are relatively inexpensive, reducing project costs.

Classification of Self-Drilling Screws

Self-drilling screws: These screws have a cruciform recess head with a fishtail design, allowing them to easily drill into and grip onto surfaces like steel, wood, and drywall.

Commonly made from stainless steel (SUS 410 and SUS 304), these screws are widely used for metal roofing systems and metal racks and shelves.
Drywall screws: These screws have two thread types: fine threads for metal and coarse threads for drywall and wood.

Materials: Galvanized alloy steel and stainless steel (SUS).

Applications: Installation on drywall surfaces, preventing water penetration due to the continuous seal from the screw head to the tail.
Lag screws: These screws have no recess on the head and feature a square or hexagonal shape with coarse threads on the shank.

Materials: Typically made from alloy steel.

Applications: Joining wooden pieces, particularly heavy materials with high load-bearing requirements.