Double Thread Hex Washer Head Bi-Metal Self Drilling Screws, Stainless Steel

Product Overview

Our Austenitic Bi-Metal Self Drilling Screws are heavy-duty industrial fasteners engineered specifically for demanding roofing, wall panel and metal framing applications, especially those involving insulated foam panels. Featuring a robust Hex Washer Head, precision Point No.5 drill tip, and specialized double thread design, these screws combine the exceptional corrosion resistance of 304/A2 or 316/A4 austenitic stainless steel with the high hardness of AISI 420 steel drill point. This bi-metal construction delivers outstanding performance: they drill faster, hold stronger, and resist rust and corrosion even in harsh outdoor environments. The double thread geometry is optimized to grip both the steel purlin and foam panel simultaneously, preventing loosening under thermal expansion, contraction and wind loads, making them ideal for long-lasting fastening in heavy metal frame structures.

Key Features

Austenitic Bi-Metal Construction: Combines 304-A2 or 316-A4 stainless steel body with AISI 420 drill point, offering superior corrosion resistance, high tensile strength, and excellent drilling hardness for extended service life in outdoor and humid environments.

Hex Washer Head Design: The large flange provides a wide bearing surface, distributing load evenly to prevent pull-through and ensure a secure, stable installation. It also creates a tight seal against the panel surface, helping to prevent water ingress and air leakage.

Point No.5 Drill Tip: Precision-engineered drill point enables fast, efficient self-drilling with a maximum capacity of 12mm, eliminating pre-drilling holes and significantly reducing installation time on-site. The sharp tip also reduces the risk of damaging the foam panel during installation.

Specialized Double Thread Design: The dual-thread geometry is optimized for insulated foam panel applications, featuring different thread pitches that enhance grip in both the steel purlin and foam core. This design prevents loosening under dynamic loads, thermal cycling and wind uplift, ensuring long-term stability.

Optimized for 12mm Steel Purlins & Foam Panels: Specifically designed for attaching metal rails to metal purlins and fastening insulated foam panels to steel structures, ensuring a tight, secure fit without damaging the panel or compromising thermal performance.

Premium Anti-Corrosion Coatings: Available with Ruspert or Dacromet coatings, offering exceptional resistance to rust, corrosion, and environmental damage, making the screws suitable for outdoor, coastal, and high-humidity environments.

Professional Performance Specs: Recommended screw driver speed of MAX 1800 R.P.M. ensures optimal drilling efficiency and prevents overheating or bit damage during installation, ensuring consistent performance across large-scale projects.

Common Applications

Attaching insulated foam panels to steel purlins in roof and wall construction

Fastening metal rails to metal purlins in heavy-duty structural applications

Industrial building, warehouse and commercial construction projects

Roofing and wall panel installation requiring long-term corrosion resistance

Outdoor and coastal construction projects with foam insulation panels