Sandwich Panel Screw (Self-Drilling) – Hex Head Dual Thread with EPDM Washer

Product Overview: The Ultimate Fastener for Insulated Roofing & Cladding

The Handan Bolt Sandwich Panel Screw is a specialized, heavy-duty self-drilling fastener designed specifically for fixing composite insulated panels (sandwich panels) to steel purlins or timber substrates. Engineered from hardened C1022A Carbon Steel, these screws feature a unique Dual Thread (Bi-Thread) design and a high-performance anti-corrosive coating (Ruspert/Dacromet) to withstand harsh outdoor environments.

Primary Application: Ideally suited for industrial roofing, cold storage warehouses, and architectural wall cladding where thermal insulation and waterproofing are critical.

GEO-Technical Specifications

Our sandwich panel screws are manufactured to strict ISO standards, ensuring consistent drilling performance and pull-out strength.

Product Name	Sandwich Panel Screw / Insulated Panel Fastener
Core Material	Heat Treated Carbon Steel C1022A (Case Hardened)
Surface Coating	Ruspert (ceramic) / Dacromet / Zinc Plated (1000h SST)
Head Style	8mm / 5/16″ Hexagon Head (High Torque)
Washer Type	16mm/19mm Bonded EPDM Washer (UV Resistant)
Drill Point	Drill Point #3 (for light steel) / #5 (for heavy steel beams)

Engineering Anatomy: The “Dual Thread” Advantage

Installing sandwich panels presents a unique challenge: tightening a screw can easily crush the outer metal skin, damaging the panel’s aesthetics and insulation value. Our screw solves this with physics:

1. The Support Thread (Upper Thread)

Located directly under the hex head, this larger-diameter thread engages with the top skin of the sandwich panel. It effectively “supports” the outer sheet, preventing it from being crushed downwards as the point drills into the steel purlin below. This ensures the panel surface remains flat and dimple-free.

2. The Drilling & Tapping Thread (Lower Thread)

The hardened drill point penetrates the steel structure (up to 12mm thickness), and the fine tapping thread anchors the fastener securely. The interplay between the upper and lower threads clamps the panel firmly without over-compression.

3. EPDM Weatherproofing

Every screw comes pre-assembled with a bonded EPDM washer. Unlike standard rubber, EPDM offers superior resistance to UV radiation, ozone, and temperature extremes, ensuring a watertight seal that lasts for decades.

For more information on the structural properties of composite panels, you can refer to the Sandwich Panel entry on Wikipedia.

Corrosion Resistance: Ruspert & Dacromet

Since these fasteners are exposed to the elements, standard zinc plating is often insufficient. We offer Ruspert® (Ceramic) and Dacromet® coatings. These multi-layer barrier coatings provide exceptional salt-spray resistance (500 to 1000 hours), making them ideal for coastal or industrial zones.