A2 Stainless Steel Cheese Head Phillips Machine Screws | M2–M8 Metric Bolts

A general rule is to select a length that allows the screw to penetrate the base material by at least 1.5× the screw diameter. For example, an M4 screw fastening a 3mm panel typically needs at least 6mm of thread engagement in the base material. If you need a quick inch reference: 10mm ≈ 3/8", 16mm ≈ 5/8", 25mm ≈ 1", 50mm ≈ 2". When in doubt, go slightly longer and use a nut or threaded insert for a secure fit.

These screws are made from A2 stainless steel, equivalent to 304 grade. A2 stainless generally offers good tensile strength for light-to-medium duty fastening. As a rough reference, M4 A2 screws typically handle around 1.2–2.0 Nm of torque, and M6 around 4–7 Nm. For load-critical or structural applications, always verify against engineering specifications.

A2 stainless steel is generally suitable for outdoor use in most standard weather conditions — rain, humidity, and temperature cycling. It resists rust and surface oxidation well. However, for coastal, marine, or salt-spray environments, A4 (316) stainless steel is typically recommended for better chloride resistance.

These are metric machine screws with ISO 68-1 coarse thread pitch. They are compatible with standard metric hex nuts, nylon lock nuts, flange nuts, and threaded inserts of the corresponding size. Common coarse pitches: M3 = 0.5mm, M4 = 0.7mm, M5 = 0.8mm, M6 = 1.0mm, M8 = 1.25mm.

The correct bit size depends on the screw diameter. As a general guide: M2–M3 typically use a PH1 bit, M4–M6 typically use a PH2 bit, and M8 may require a PH3 bit. Always use a well-fitting bit to avoid cam-out and head damage, especially on smaller sizes like M2 and M2.5.

Cheese head screws have a taller, narrower cylindrical head compared to pan head screws, which have a wider, lower-profile dome. Cheese heads are generally preferred when the screw needs to fit inside a counterbore or recess, or when a taller drive recess depth is needed for better bit engagement. Pan heads are more common for general surface mounting where a wider bearing surface is beneficial.

Yes, A2 stainless machine screws are generally reusable multiple times as long as threads are not damaged. When threading into softer materials like aluminum or plastic, use appropriate torque — over-tightening can strip the receiving threads. For plastic, a thread-forming insert (e.g., heat-set brass insert) is typically recommended for repeated assembly and disassembly.