This non-standard, cold-forged carbon steel, zinc-nickel alloy, black, oversized hexagonal self-tapping screw with black, enlarged ferrule washer is a high-performance fastener. Cold-forged from carbon steel with a zinc-nickel alloy finish and a black exterior, it features an oversized ferrule washer and an external hexagonal drive mechanism. It is a self-tapping screw.
Product Features
Material: The carbon steel base provides high strength, while the zinc-nickel alloy plating (8-12μm) provides excellent corrosion resistance (salt spray test resistance up to 500-1000 hours).
Design: The oversized ferrule washer (20-30% larger than a standard washer) provides improved pressure distribution and sealing.
Drive: The external hexagonal head facilitates tool force application and provides efficient torque transmission.
Self-tapping: The special thread design allows for self-tapping internal threads on the connected components.
Applications: Outdoor equipment assembly requiring high corrosion resistance
Connections between thin sheet metal parts (recommended sheet thickness 0.8-3mm).
Applications requiring special sealing and pressure distribution.
For applications requiring quick installation due to limited space.
Instructions
1. Pre-installation Preparation
Hole Preparation: Pre-drill a pilot hole in the connected component (hole diameter approximately 75-85% of the nominal screw diameter).
Surface Preparation: Remove oil and burrs from the connecting surface and ensure a smooth contact surface.
Tool Selection: Use a socket or wrench with a matching hexagonal head (a torque wrench is recommended).
2. Installation Procedure
Place the washer facing the surface of the connected component.
Initially, align the screw perpendicularly into the hole at a low speed (≤300 rpm).
Apply appropriate axial pressure to initiate the tapping (initial torque approximately 30% of the final torque).
Once the threads are fully engaged, increase the speed to 500-800 rpm.
Stop immediately upon reaching the preset torque (typical installation torque reference: M6 approximately 8-10 N·m).
3. Precautions
Torque Control: Over-torque operation is strictly prohibited, as it may cause thread stripping or screw breakage.
Reusability: Self-tapping screws are not recommended for repeated disassembly and assembly (maximum 2-3 times).
Material Compatibility: Not suitable for substrates with a hardness of HRC > 35 or thin plates with a thickness of < 0.5mm.
Corrosion Protection: Damaged plating is recommended for re-application of a special anti-corrosion coating.
Common Problems
Accessibility: Check if the hole diameter is too small or misaligned; re-enlarge the hole appropriately.
Head Slippage: Ensure the tool fits snugly against the hexagonal head and replace the tool if necessary.
Washer Displacement: A small amount of thread sealant may be used to temporarily secure the washer before installation.
Corrosion Protection: Regular inspection is recommended for environments with high salt spray.
Proper use of this non-standard fastener ensures connection reliability and long-term corrosion protection. Sample testing is recommended before initial batch use.
