Lag Screws (Hex Wood Screws) are used primarily for structural and machine joints that must be tightened to a controlled preload. This page summarizes where they fit, the industries that rely on them, and the practical points to get right when you specify them — to DIN 571. Stocked across roughly M5 to M24, they cover general to heavy-duty work.
Typical Applications for Lag Screws (Hex Wood Screws)
The most common settings where these are specified:
- Automotive & transport: chassis, suspension and powertrain mounting points subject to vibration.
- Heavy machinery: securing gearboxes, frames and guarding on plant that sees shock loads.
- Energy & infrastructure: tower, pylon and pipework supports exposed to weather and long service life.
- General machine building: fastening covers, brackets, motors and sub-assemblies on production equipment.
- Maintenance & repair (MRO): a stocked size for servicing existing plant where the original fastener spec must be matched.
How to Specify Lag Screws (Hex Wood Screws) for Your Application
- Size: Match the nominal size to the mating thread or hole. This product spans M5–M24; check the full table below for the exact dimensions of each size.
- Strength class: Choose the property class (e.g. 8.8, 10.9, 12.9 or A2/A4 stainless) for the load and environment, and tighten to the matching torque so the joint relies on preload, not friction.
- Environment: For damp, coastal or chemical exposure prefer A4/316 stainless or a suitable coating; indoors, plated steel or A2 is usually sufficient.
- Standard: This product is supplied to DIN 571. Quoting the standard on your order guarantees interchangeable dimensions between suppliers.
Where Lag Screws (Hex Wood Screws) Are Not the Right Choice
Not for permanent joints that will never be opened (a rivet or weld is cheaper), and not where the head must sit flush — use a countersunk screw instead.