M3 M4 M5 Aluminum Phillips Truss Head Screws DIN 7983 – Metric Machine Bolts

Match the thread diameter (M3, M4, or M5) to your tapped hole or threaded insert. For length, measure the thickness of the material being fastened — the screw length should be at least equal to that thickness for a through-hole application, or at least 1.5× the thread diameter for engagement in a tapped hole. For example, a 3mm (≈1/8”) thick panel with a through-hole typically calls for an M3 x 4mm or M3 x 5mm screw. When in doubt, go one size longer.

Aluminum alloy screws are generally lighter and more corrosion-resistant than steel, but have lower tensile strength. Aluminum fasteners are typically suited for light-duty to medium-duty applications where weight reduction, non-magnetic properties, or corrosion resistance are priorities — such as electronics enclosures, RC vehicles, and consumer product assembly. For high-load structural applications, steel or stainless steel fasteners are generally more appropriate. Contact us to confirm suitability for your specific load requirements.

Aluminum naturally forms a stable oxide layer that provides good corrosion resistance in most outdoor and humid environments without additional coating. These aluminum truss head screws are generally suitable for outdoor electronics enclosures, signage, and light-duty outdoor fixtures. For saltwater or highly acidic environments, contact us to confirm suitability.

These screws conform to DIN 7983 and follow the ISO metric coarse thread standard. M3 uses a 0.5mm pitch, M4 uses a 0.7mm pitch, and M5 uses a 0.8mm pitch. They are compatible with standard metric tapped holes, threaded inserts, and metric nuts of the same diameter and pitch. They are not compatible with UNC/UNF (inch) threads.

A truss head (also called a mushroom head or oval binding head) has a wider, lower-profile dome than a standard pan head, giving it a larger bearing surface that distributes clamping force over a greater area. Unlike a flat (countersunk) head, the truss head sits on top of the surface rather than flush with it. This makes it ideal for applications where you need to clamp thin or soft materials without the head pulling through — such as sheet metal, plastic panels, and thin composite sheets.

M3 screws typically use a PH1 (Phillips #1) driver. M4 and M5 screws typically use a PH2 (Phillips #2) driver. Always use a driver that fits snugly in the recess to minimize cam-out risk. Apply firm downward pressure while driving, especially in aluminum, which is softer than steel and more susceptible to head damage if the wrong driver size is used.

For prototyping or small repairs, 20–50 pcs is generally sufficient. For workshop restocking or small production runs, 100–250 pcs is a practical choice. For ongoing manufacturing, assembly lines, or high-volume builds, 500–2500 pcs offers the lowest per-unit cost and reduces reorder frequency. All quantities ship from our US warehouse in secure packaging.