M4 M5 Pan Head Machine Screws — Phillips/Pozidrive, A4 Stainless Steel

Generally, the screw length should equal the thickness of the material being fastened plus enough thread engagement in the receiving part — typically 1.5× the screw diameter. For example, an M4 screw threading into metal typically needs at least 6mm of thread engagement. If you need a quick inch conversion: 25mm ≈ 1 inch, so a 50mm screw is approximately 2 inches long, and a 100mm screw is approximately 4 inches long.

Phillips (PH) and Pozidrive (PZ) look similar but are not identical. Pozidrive has additional ribs between the cross slots that provide better torque transfer and reduce cam-out. In most cases, a Pozidrive bit fits both types, but using the correct bit for each drive type is recommended for best results and to avoid damaging the head recess.

A4 (316) stainless steel machine screws are generally rated to property class 70 or 80, offering tensile strengths typically in the range of 700–800 MPa depending on diameter and manufacturer. They are well-suited for structural and mechanical fastening where corrosion resistance is also required. For safety-critical load calculations, contact us to confirm the exact property class of the specific variant.

Yes. A4 stainless steel (also known as 316 grade) contains molybdenum, which provides superior resistance to chloride corrosion compared to A2 (304) stainless. These screws are generally well-suited for outdoor, coastal, and marine environments. For fully submerged or highly aggressive chemical environments, contact us to confirm suitability for your specific application.

These screws follow the ISO metric coarse thread standard. M4 has a standard pitch of 0.7mm and M5 has a pitch of 0.8mm. They are compatible with standard metric nuts (DIN 934), flat washers (DIN 125), spring washers, and tapped holes conforming to ISO 68-1. They are not compatible with UNC/UNF inch-thread hardware.

M4 screws have a 4mm shank diameter and are typically used in lighter assemblies, electronics enclosures, and thin sheet metal. M5 screws have a 5mm shank and are generally chosen for applications requiring higher load capacity or where the mounting hole is sized for M5. Check your existing hardware, the tap size of your threaded hole, or measure the clearance hole diameter to confirm which size is needed before ordering.

Yes. These pan head machine screws use standard ISO metric coarse threads and are compatible with DIN 934 hex nuts, DIN 125 flat washers, DIN 127 spring washers, and other standard metric hardware in the corresponding M4 or M5 size. They also work with standard metric threaded inserts and rivet nuts.