IFI 502 Metric Slotted Flange Hexagon Head Self-Tapping Screws
This product is a metric self-tapping screw manufactured to IFI 502 (equivalent to ASME B18.6.4), featuring a hexagon head with an integrated flange and a slotted drive. The flange replaces the need for a separate washer, distributing clamp load over a larger bearing surface while the self-tapping thread cuts or forms its own mating thread when driven into pre-drilled holes in metal, plastic, or composite materials, eliminating the need for pre-tapped nuts or threaded inserts. Available in carbon steel (case-hardened) and stainless steel variants, with thread types including A, AB, B, BF, C, D, and F, this product is suitable for blind-hole assembly and field installation where access is limited to one side of the joint.
What are the dimensional specifications and available thread sizes for IFI 502 slotted flange hexagon head self-tapping screws?
The hexagon flange head geometry features an integrated washer-like flange that provides a larger bearing surface without a separate washer component. The slotted drive in the head allows torque application using a standard flat-blade screwdriver, with cross recess (Phillips or Pozidriv) also available as optional drive styles. Thread size availability varies by thread type. For general purpose tapping screws (Types AB, B, BF, BP, C, D, F, and T), sizes range from ST2.2 to ST9.5 (ST = metric self-tapping thread) in 84 distinct sizes, with thread length and overall length specified in IFI 502 dimensional tables.
What material property classes and mechanical performance requirements apply to these screws?
For carbon steel versions, the screw material is case-hardened low‑carbon steel (typically C1010–C1022), heat‑treated to achieve a surface hardness sufficient for thread‑forming or thread‑cutting action (typically HRC 45–52) while maintaining a ductile core to prevent brittle failure under torsional load. The typical core hardness requirement is HRC 35–45 measured on a cross‑section at one to two times the nominal diameter from the screw tip. For stainless steel variants, material grades such as 304 (A2) and 316 (A4) are available, providing corrosion resistance for outdoor, marine, or chemically exposed environments. Verification testing includes drive torque, strip torque, torsional strength, and case depth measurement per IFI 502 requirements, as well as Core Hardness requirements (excluding case‑hardened zones) tested via microhardness methods.
How does the integrated flange design affect installation and performance compared to standard hexagon head screws?
The integrated flange, with a bearing surface diameter approximately 1.5 to 1.8 times the thread diameter, distributes clamping load over a larger area compared to standard hexagon head screws, reducing the risk of surface indentation and eliminating the need for a separate flat or lock washer. The flange also provides a smooth, serrated (for locking versions) or plain bearing surface that minimizes gapping between fastened components under vibration. For locking variants, the flange incorporates under‑head serrations which bite into the workpiece surface to provide prevailing torque against loosening. Available surface finishes for carbon steel variants include zinc plating (clear, yellow, or black passivation), phosphate coating (grey or black), and mechanical zinc plating for enhanced corrosion protection.
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