Bi-Metal Self-Drilling Screws: Comprehensive Product Details
Premium Corrosion-Resistant Fasteners for Structural Applications
Product Overview
Bi-Metal Self-Drilling Screws combine the superior corrosion resistance of 300-series stainless steel with the high drilling efficiency of hardened 400-series stainless steel or alloy steel tips. These fasteners are engineered to deliver reliable, long-lasting performance in demanding industrial environments, eliminating the trade-off between durability and corrosion resistance common with standard fasteners.
By welding two distinct materials together — an exposed stainless steel head and shank, and a hardened carbon steel tip — these screws offer exceptional performance in both indoor and outdoor applications. The stainless steel body resists rust and corrosion, while the hardened tip ensures effortless self-drilling and self-tapping capabilities, even in high-strength substrates.
Product Specifications
| Item | Details |
|---|---|
| Product Name | Bi-Metal Self-Drilling Screws |
| Material | Body: SUS304 / SUS316 Stainless Steel Tip: SUS420 Stainless Steel / SCM435 Alloy Steel |
| Surface Treatment | Zinc Plated, Ruspert Coated (500h/1000h Salt Spray), Plain Finish |
| Head Types | Hex Washer Head (HWH), Hex Flange Head, Flat Head, Modified Truss Head |
| Point Types | Drill Point (#2 / #3 / #5), Sharp Point |
| Available Sizes | Diameter: M4.2 / M4.8 / M5.5 / M6.3 (#8 / #10 / #12 / #14) Length: 25mm to 280mm (Custom lengths available) |
| Thread Specification | Coarse Thread, Custom Thread Pitch (TPI) |
| Standard | DIN / ISO Compliant |
| Packaging | Box + Carton, Custom packaging available upon request |
| Samples | Available |
Core Design & Material Configuration
Bi-Metal screws are precision-engineered in three key parts to deliver optimal performance. The welded integration of stainless steel body and hardened tip eliminates the risk of joint failure, providing exceptional durability under torsion and tensile stress.
The welding joint (C) undergoes 100% inspection to guarantee consistent performance. This configuration ensures the screw can handle high-torque installation while maintaining stainless steel’s anti-corrosion properties for the entire exposed length.
Material: SUS304 / SUS316 Stainless Steel. No case hardening, preserving max corrosion resistance. Surface hardness: 350HV min. Tensile strength exceeds A2 standard (700N/mm²).
High-strength welded connection. Welding strength exceeds breaking values for torsion and tensile, ensuring joint will not fail before the screw itself.
Material: SUS420 / SCM435 alloy steel. Case-hardened (>600HV). Available in #2, #3, #5 drill point configurations. Enables self-drilling through steel plates without pre-drilling.
Key Features & Benefits
Combines stainless steel corrosion resistance with hardened alloy drilling performance.
Hardened drill points penetrate steel up to 12mm thick (#5 point), reducing installation time.
Stainless steel bodies + Ruspert coating (500h–1000h salt spray).
High strength, ductility, and resistance to HASCC.
Steel-to-steel, steel-to-stainless steel, and aluminum connections.
Technical Performance Data
Drilling Capacity (Maximum Combined Material Thickness)
Mechanical Properties (Steel-to-Steel Connections)
| Thread Size | Material | Pull-Out Load (Min.) |
|---|---|---|
| #8 / M4.2 | SUS304+SS420 | 4000 N |
| #10 / M4.8 | SUS304+SS420 | 6000 N |
| #12 / M5.5 | SUS304+SS420 | 8500 N |
| #14 / M6.3 | SUS304+SS420 | 10000 N |
How to Select the Correct Screw Length
To achieve full connection strength, the screw must be long enough to ensure at least 3 full threads protrude through the substrate material. When calculating the required length, always include:
- The total thickness of all materials being joined
- Any gaps or spaces between substrates
- The length of the drill point
Bi-Metal self-drilling screws are widely used in applications where both corrosion resistance and structural integrity are critical: Construction & Building, Steel framing, roof installation, curtain wall systems; Industrial: Wire mesh assemblies, machinery manufacturing; Energy: Oil & gas facilities; Chemical & Pharmaceutical; Maritime & Aerospace; Food & Beverage.
Available Head Styles & Markings
Bi-Metal self-drilling screws are available in multiple head configurations to suit various installation requirements and surface finish needs. Each head style is designed to provide optimal torque transfer and reliable clamping force.
Large bearing surface, high clamping force
Low-profile design for flush finish
Countersinks flush with surface
Ultra-low profile for tight spaces
Markings on the head indicate thread size, material grade, and custom TPI specifications. Custom laser etching or color coding is also available for traceability and brand identification.
Material Chemical Composition
| Material | C (Max) | Mn (Max) | P (Max) | S (Max) | Si (Max) |
|---|---|---|---|---|---|
| SUS304 | 0.08 | 2.00 | 0.045 | 0.03 | 1.00 |
| SUS316 | 0.08 | 2.00 | 0.045 | 0.03 | 1.00 |
| SUS420 | 0.16-0.25 | 1.00 | 0.04 | 0.03 | 1.00 |
| SCM435 | 0.33-0.38 | 0.6-0.9 | 0.03 | 0.03 | 0.15-0.3 |
Why Choose Our Bi-Metal Screws?
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