A Phillips Flat Head Self Drilling Screw with Wing Nibs (sometimes called a "winged TEK screw" or "countersunk wing drill screw") is a multi-purpose fastener engineered to connect a soft material — typically wood, fiberboard, or insulation board — to a metal substructure in a single-step operation, without any pilot hole.
Three defining design features work in concert:
This combination makes it a one-shot fastener for composite roofing assemblies, decking, cladding panels, and light steel-frame construction — a category of significant growth in global building activity.
You can view Tuyue's full product specification for this screw at: Phillips Flat Head Self Drilling Screw With Wing Nibs Under the Head.
The flat head geometry typically follows an 82° or 90° countersink angle, conforming to international standards such as ISO 7050 and ASME B18.6.4. When driven correctly, the head sits perfectly flush — critical in roofing and cladding where surface protrusions can catch wind, cause water pooling, or interfere with overlaid membranes.
The Phillips recess (also called a cross recess, standardized under ISO 8764) provides good cam-out resistance at moderate torque — a balance point that helps prevent over-driving in power tool applications. The No. 2 Phillips drive is universal and compatible with virtually all impact drivers and screw guns used on construction sites worldwide.
The wings are arguably the most innovative element. Positioned symmetrically below the head on the upper shank, they extend laterally 2–5 mm beyond the thread diameter, depending on screw size. Their function is a two-stage operation:
The wing geometry is carefully calibrated. Too brittle and they break prematurely in dense hardwood; too tough and they fail to fracture on thin-gauge steel. Most commercial wing screws are engineered to break at contact with steel ≥0.6 mm thick — often tested against G550-grade galvanized sheet.
The drill point is CNC-ground from heat-treated carbon steel (typically C1022 or equivalent, quench-hardened to 50–55 HRC). The two-flute geometry creates chip-clearing channels that prevent clogging and reduce heat buildup. TEK drill points are classified by number (TEK 1 through TEK 5) based on the maximum steel thickness they can penetrate without pre-drilling:
Wing-nib screws designed for composite roofing panels most commonly use TEK 2 or TEK 3 points, as they pair optimally with typical purlin gauges of 1.5–3.0 mm.
The thread profile is typically a Type 17 (modified "A" thread) — a coarse-pitch, sharp-crested thread optimized for metal cutting rather than wood compression. This geometry maximizes pull-out resistance in thin steel while still providing acceptable holding in wood. Thread OD commonly ranges from 4.2 mm to 6.3 mm for roofing applications, with pitches from 1.4 to 1.8 mm per revolution.
Figure 2 — The wing nib breakaway sequence. Stage 1: wings ream a clearance oversize hole in the soft panel. Stage 2: wings fracture on metal contact, allowing the screw to thread-grip the steel substrate at designed torque.
The screw body is typically cold-formed from medium-carbon steel (AISI C1022 or SAE 1022), offering a good balance between formability during heading and thread rolling, and the hardness achievable through heat treatment. After forming, the screws undergo induction or batch hardening (quench & temper) targeting a core hardness of 32–38 HRC and a surface hardness of 50–55 HRC at the drill point — high enough to penetrate structural steel, yet with sufficient core toughness to resist torsional failure during installation.
Electroplated zinc provides a sacrificial cathodic barrier against corrosion. Under ISO 4042 and ASTM B633, the zinc layer thickness on standard commercial screws is typically 5–8 µm (Class Fe/Zn 5 or Fe/Zn 8). A 5 µm deposit provides roughly 48–96 hours of salt spray resistance per ASTM B117 before the first red-rust appearance, which, while adequate for interior applications, is insufficient for exposed roofing environments without an additional passivation layer.
This is where the zinc-plated phosphate coated specification of Tuyue's product becomes technically significant. A manganese or zinc phosphate conversion coating is applied over the base zinc layer. The phosphate microcrystalline structure:
The combination of zinc + phosphate is the industry standard for roofing self-drilling screws in moderate-exposure environments. For highly corrosive coastal or industrial environments, alternative coatings such as Ruspert, Geomet, or stainless steel construction may be preferred — all of which Tuyue also supplies across their roofing screws and drilling screws product range.
Figure 3 — Schematic cross-section of the multi-layer coating system on zinc-plated phosphate-coated self-drilling screws. Each layer adds a distinct functional benefit to the overall corrosion resistance and installation performance.
Fixing metal or fiber-cement roofing sheets over steel purlins through an intermediate insulation or plywood board. The wing nib prevents the insulation layer from pulling up or rotating during installation.
Attaching timber or engineered wood cladding to light steel frames in residential and commercial construction. The flush head allows water to run off cleanly without snagging.
Joining SIP panels — typically OSB-foam-OSB sandwiches — to steel-framed structures. Wings clear the OSB without splitting fibers; the self-drilling tip penetrates the underlying steel rail.
Securing timber or composite deck boards to steel joists in elevated deck construction. The countersunk head sits flush for a smooth walking surface and safe underfoot feel.
High-volume use in prefabricated and modular building assembly where speed of installation is a priority and pre-drilling is cost-prohibitive at scale.
Mounting rail and ballast system components to metal sub-frames on rooftop PV installations. For solar-specific applications, Tuyue offers dedicated solar and photovoltaic module fasteners.
Use a variable-speed reversible (VSR) drill or impact driver set to a clutch torque of 6–10 N·m for 4.8 mm screws, adjusting up for larger diameters. The No. 2 Phillips bit should be magnetic and in good condition — worn bits cause cam-out that can strip the recess head before full seating. For production-scale installation, a dedicated screw gun with depth-sensing nose piece is strongly recommended to maintain consistent seating depth across hundreds of fastening points.
Self-drilling screws perform best at 1,500–2,500 RPM. Too slow and the drill point fails to generate sufficient chip-clearing force; too fast and friction heat can reduce drill tip hardness through localized annealing. When drilling through material stacks exceeding 25 mm combined, reduce speed by 20–30% and allow the screw to clear chips between bursts.
For maximum axial pull-out resistance in steel, the engaged thread length in metal should be at least 3 thread pitches (typically ≥4 mm). For the wing-nib design, this means selecting a screw length equal to the soft panel thickness + ≥6 mm into the steel substrate. Under-engagement is a structural safety concern in high-wind uplift applications such as roofing.
Tuyue provides a broad length range for this product, and for engineering calculations, you can reference their FAQ page for product selection guidance or contact the technical team directly.
The Phillips flat head wing screw is one fastener in a comprehensive ecosystem of self-drilling and roofing fasteners. Depending on application requirements — substrate thickness, environmental exposure, aesthetic finish, or load rating — the following related products from Zhejiang Jiaxing Tuyue Import & Export Co., Ltd. may be relevant:
