Key components:
Drill bit: Responsible for drilling holes. The material and heat treatment process determine how thick the steel it can penetrate.
Thread: Responsible for tightening and tightening. Different pitch designs are suitable for different materials and fastening requirements.
Gasket: Provides sealing and pressure-bearing surface. High-quality EPDM gaskets can effectively protect against water and dust.
Screw: The strength and corrosion resistance of the body are crucial.
4 key factors in choosing drill tail screws)
1. Screw specifications (diameter and length)
Diameter: Common ones are #12, 1/4 inch, etc. The larger the diameter, the stronger the pulling force. For conventional roofing sheets, ST4.8 or #12 are common choices.
Length: Total length = total thickness of material to be penetrated + meshing length of at least 25mm. For example, to penetrate 2mm steel plate and 50mm purlin, it is recommended to choose at least 2mm + 50mm + 25mm = 77mm screws, usually 80mm or longer.
2. Drill type (match to material thickness - this is the core!)
The drill bit model determines its penetration capabilities. Choosing the wrong drill bit is a leading cause of installation failure.
No. 1 drill bit: suitable for steel with thickness ≤ 2.0mm.
Material and coating (determines corrosion resistance life)
Material: Usually carbon steel, hardened by heat treatment.
coating:
Ordinary galvanizing: suitable for ordinary indoor environments.
Mechanical galvanizing: The coating is thicker and has stronger rust resistance.
Dacromet/Hongzincfen: Highly recommended for use outdoors or in highly corrosive environments. It provides excellent anti-rust performance and can survive salt spray testing for more than 500 hours without the appearance of red rust.
4. Gasket quality (guardian of sealing)
EPDM gasket: the first choice for metal roofs. It has excellent elasticity and weather resistance, and can remain sealed and prevent water leakage under long-term sun and rain.
Check the gasket: Make sure it is tightly bonded to the metal cap and has no cracks or imperfections.