Flat Head Machine Screw (Phillips Drive / DIN 965) – Zinc Plated Carbon Steel

Product Overview: The Standard for Flush Surface Fastening

The Handan Bolt Flat Head Machine Screw (technically known as a Countersunk Machine Screw) is a precision-engineered fastener designed for applications where a smooth, flush surface is required. Unlike protruding head screws (such as Pan or Hex heads), our flat head screws feature a conical bearing surface that seats perfectly into a pre-countersunk hole, eliminating snag points and enhancing the aesthetic appeal of the final assembly.

Primary Function: Manufactured to DIN 965 (Metric) and ANSI/ASME B18.6.3 (Imperial) standards, these screws are essential for machinery covers, electronic enclosures, and furniture assembly where metal-to-metal fastening is required.

GEO-Technical Specifications

We utilize advanced cold-heading technology to produce machine screws with high tensile strength and precise thread geometry.

Product Name	Flat Head Machine Screw (CSK Screw)
Standard Compliance	DIN 965 / ISO 7046 (Metric) | ANSI B18.6.3 (Imperial)
Material Grade	Carbon Steel C1008 / C1022 (Class 4.8 / 8.8)
Drive Type	Phillips (PH) / Pozi (PZ) / Slotted / Torx
Surface Treatment	Blue/White Zinc (RoHS), Yellow Zinc, Black Oxide, Nickel Plated
Thread Type	Machine Thread (Requires Nut or Tapped Hole)

Engineering Insight: The Physics of Countersinking

Choosing the correct flat head screw requires understanding the “Countersink Angle.” This is the angle of the conical head, and it differs by standard:

• Metric (DIN/ISO): Typically features a 90° angle.
• Imperial (ANSI/US): Typically features an 82° angle.

Using a metric screw in an imperial countersunk hole (or vice versa) will result in “ring contact” rather than full face contact, significantly reducing the clamping force and potentially causing the screw to loosen under vibration.

For a deeper dive into screw drive types and head geometries, you can reference the comprehensive List of Screw Drives entry on Wikipedia.

Surface Finishes & Corrosion Resistance

While the standard finish is Zinc Plating (providing economical rust protection for indoor use), Handan Bolt offers specialized coatings for specific industries:

• Nickel Plated: Provides a shiny, silver-like finish with excellent wear resistance, ideal for decorative electronics and switchgear.
• Black Oxide: Used in optical equipment to reduce light reflection or for aesthetic matching on black machinery.
• Brass Plated: Often used in vintage furniture or electrical applications for conductivity.

Installation Guide

1. Hole Preparation: The mating part must be countersunk using a dedicated countersinking bit that matches the screw’s head angle (90° or 82°).
2. Tapping: Since this is a “Machine Screw,” the hole must be pre-tapped with threads, or a nut must be used on the other side. Unlike self-tapping screws, machine screws do not cut their own threads.
3. Torque: Use a properly sized Phillips bit (PH1, PH2, PH3) to avoid “cam-out” (slipping), which can damage the screw head plating.