Stainless Steel Phillips Pan Head Screws with Flat and Spring Washers M1.6 to M5

Match the thread diameter (M1.6, M2, M3, M4, or M5) to your tapped hole or nut. For length, measure the total thickness of the material being clamped and add at least 1.5× the thread diameter for thread engagement. For example, clamping 4mm of material with M3 typically calls for a 6mm (≈1/4") or 8mm (≈5/16") screw. The M3×10【L】 variant has an extended shank — useful when extra grip length is needed in deeper assemblies.

The flat washer distributes clamping load over a wider surface, protecting the workpiece and reducing pull-through risk. The split spring (lock) washer sits between the flat washer and the mating surface, providing a spring-back force that resists loosening from vibration. Together they form a three-piece fastener assembly that is significantly more secure than a plain screw alone — without needing thread-locking adhesive.

Yes, these screws are stainless steel. The exact grade (typically 304 or 316) can vary by batch. Grade 304 is suitable for most indoor and light outdoor applications. Grade 316 offers better resistance to salt, chlorides, and marine environments. Please contact us to confirm the specific grade if your application has strict corrosion requirements.

Stainless steel generally provides good corrosion resistance for outdoor and humid conditions. For marine, coastal, or salt-spray environments, 316 stainless is generally preferred. Contact us to confirm the grade before ordering for demanding outdoor applications. Avoid pairing stainless fasteners with dissimilar metals in wet conditions to prevent galvanic corrosion.

These screws follow the ISO metric coarse-pitch thread standard (M-series). They are compatible with standard metric tapped holes, threaded inserts, and metric hex nuts of the corresponding size — M1.6, M2, M3, M4, or M5. They are not compatible with UNC/UNF inch-series threads.

Recommended tightening torque varies by diameter and stainless grade. As a general reference: M3 stainless typically handles 0.5–0.9 N·m, M4 typically 1.2–2.5 N·m, and M5 typically 2.5–4.5 N·m. Always verify torque specs against your specific application. Note that stainless steel can gall (seize) under high torque — applying a small amount of anti-seize lubricant is recommended for larger sizes.

Use the correct bit size to prevent cam-out and head damage: M1.6–M2 generally use a PH0 bit; M3 generally uses a PH1 bit; M4–M5 generally use a PH2 bit. A hand screwdriver or low-speed power driver is recommended for small stainless screws to avoid stripping the recess.

Yes. Every size is available in quantities of 1, 5, 10, or 50 pieces. Order a single piece to verify thread fit, washer clearance, and head profile in your assembly before committing to a larger pack. The 50-piece pack offers the lowest per-unit cost for production or repeat-repair use.