The Zinc Plated Carbon Steel Hex Head Wood Screw (commonly referred to as a hex lag screw, lag bolt, heavy-duty wood tapping screw, or DIN 571 / GB/T 102 fastener) is a rugged, heavy-duty threaded fastener engineered for timber construction, heavy machinery wood framing, and masonry anchor plug installations. Featuring a sturdy hexagonal head, it allows operators to apply significantly higher driving torque using power sockets or wrenches compared to standard recessed wood screws. Below the smooth unthreaded shank, deep coarse wood threads bite firmly into wood fibers, providing exceptional pull-out resistance in full compliance with global ISO standards.
Technical Specifications of Hex Head Wood Screws
We manufacture Class 4.8 low carbon steel hex lag screws in both Electro-Zinc Plated and Hot-Dip Galvanized (HDG) finishes. The partial thread design with a plain unthreaded shank section reduces driving friction while drawing connected timber members tightly together.
| Parameter | Electro-Zinc Plated Lag Screw (DIN 571) | Hot-Dip Galvanized (HDG) Lag Screw |
|---|---|---|
| Material Grade | Class 4.8 Low Carbon Steel (Q195 / Q235B) | Class 4.8 Low Carbon Steel (Q235B) |
| Tensile Strength | 400 N/mm² (Yield Strength ≥ 320 N/mm²) | 400 N/mm² (Yield Strength ≥ 320 N/mm²) |
| Protective Coating Thickness | 5 µm – 12 µm Electro-Zinc Plated (Cr3+) | 45 µm – 65 µm Molten Hot-Dip Zinc Coating |
| Shank Profile | Partial Thread with Plain Unthreaded Body | Partial Thread with Plain Unthreaded Body |
| Driving Tool Type | Hex Socket Wrench / Impact Power Driver | Hex Socket Wrench / Impact Power Driver |
Precision Cold Heading, Thread Rolling, and Plating Process
At our manufacturing facility in Handan, China, hex head wood screws are produced using automated cold heading formers, deep-thread rolling machines, and galvanizing lines:
- Heavy Multi-Station Cold Heading: High-tonnage cold formers press carbon steel wire rod into exact hexagonal heads and smooth shanks with sharp across-flat dimensions that prevent wrench slippage.
- Deep Wood Thread Rolling: Specialized thread rolling machinery cuts sharp, deep gimlet points and wide-pitch wood threads for fast penetration into hardwoods and softwoods.
- Electro-Zinc Plating & Passivation: Trivalent chromium (Cr3+) electro-galvanizing deposits a bright 5–12 µm protective zinc layer, followed by de-embrittlement baking.
Key Engineering Applications of Hex Head Wood Screws
Hex head lag screws offer reliable heavy-duty clamping across timber and structural masonry applications:
- Timber Framing & Wooden Bridges: Fastening heavy wooden posts, roof trusses, timber deck joists, and log home frames.
- Wooden Pallets & Heavy Machinery Crate Packaging: Securing heavy industrial equipment onto timber skids and wooden shipping crates.
- Masonry Wall Anchoring with Expansion Plugs: Paired with nylon or plastic wall expansion plugs to anchor heavy brackets, machinery bases, and steel plates into concrete or brick walls.
Quality Control and Export Packaging for Hex Wood Screws
Handan YiHao Fastener enforces strict Quality Assurance (QA) standards for all overseas export orders. Testing procedures include 100% hex head dimension checks across flats, thread pitch gauge verification, micrometer shank diameter testing, and salt spray validation.
All export items are bulk packed in heavy-duty 25kg inner cartons, neatly stacked on ISPM 15 compliant fumigated wooden pallets, and wrapped in protective stretch film for safe ocean freight.
Request Factory Direct Pricing for Hex Head Wood Screws
Looking for a trusted manufacturer in Handan, China for Class 4.8 zinc plated hex head wood screws / lag bolts (DIN 571, GB/T 102)? Contact Handan YiHao Fastener today for technical datasheets, free samples, and direct bulk export quotes.
