Name: Hex Head Flange Self Driling Screw 3# Tail
Rating: 5 (99 reviews)

Specification: ST5.5-24*50

Material: SUS410

Surface Treatment: Silver Dacromet

Single weight：8.8

Product Introduction

The Hex Head Flange Self-Drilling Screw with 3# Tail is designed for heavy-duty metal fastening applications requiring high torque transmission and enhanced drilling capability. The hex head flange configuration combines the torque capacity of a hexagonal drive with an integrated flange that eliminates the need for a separate washer, providing accurate load distribution across the bearing surface. The 3# tail design features an extended drill point that provides enhanced drilling capability for thicker material stacks, enabling efficient penetration into heavier gauge substrates. The self-drilling point drills and taps threads simultaneously, eliminating pilot hole requirements and reducing assembly time. Manufactured from SUS410 stainless steel with silver Dacromet surface treatment, this screw provides hardness and corrosion resistance for demanding environments. The ST5.5-24 thread specification with 50mm length offers engagement for structural connections and heavy-duty metal assemblies.

Core Advantages

Hex Head Flange Design

Integrated flange eliminates separate washer requirement and provides accurate load distribution with high torque transmission capability.

3# Tail Extended Drill Point

Enhanced drilling capability for thicker material stacks enables efficient penetration into heavier gauge substrates.

Self-Drilling Point

Drills and taps threads in a single operation, eliminating pilot hole requirements and reducing installation time.

SUS410 Stainless Steel

Provides hardness for metal fastening applications with corrosion resistance for demanding environments.

Silver Dacromet Coating

Provides high corrosion resistance with extended salt spray protection and a silver metallic aesthetic finish.

Heavy-Duty Specification

ST5.5-24 thread with 50mm length provides engagement for structural connections and heavy-duty metal assemblies.

Product Features

Hex head flange configuration Integrated flange eliminates separate washer requirement and provides accurate load distribution for secure clamping in structural applications.

3# tail extended drill point Enhanced drilling capability for thicker material stacks enables efficient penetration into heavier gauge metal substrates.

Self-drilling point Drills and taps threads simultaneously, eliminating pilot hole drilling and reducing installation steps.

SUS410 stainless steel material Provides hardness for metal fastening applications with corrosion resistance for demanding environments.

Silver Dacromet surface treatment Offers high corrosion resistance with salt spray protection and a silver metallic aesthetic finish suitable for outdoor and industrial applications.

ST5.5-24 thread specification Standardized thread configuration provides consistent performance for structural connections and heavy-duty metal assemblies.

50mm length Extended length provides engagement for thicker material stacks and structural connections.

Application Scenarios

Thick metal structural connections

Heavy equipment assembly

Steel frame construction

Bridge and infrastructure

Industrial machinery

Railway applications

Shipbuilding

Heavy-duty metal fabrications

This hex head flange self-drilling screw with 3# tail is deployed in heavy-duty metal fastening applications requiring enhanced drilling capability for thicker material stacks. Applications include thick metal structural connections where reliable fastening is essential, heavy equipment assembly, steel frame construction, bridge and infrastructure projects, industrial machinery, railway applications, shipbuilding, and heavy-duty metal fabrications where the 3# tail provides enhanced penetration, the flange head offers load distribution, and the silver Dacromet coating ensures long-term corrosion protection.

Common Questions and Solutions

What is the 3# tail and what are its benefits?

The 3# tail refers to an extended drill point length that provides enhanced drilling capability for thicker material stacks. This allows the screw to penetrate heavier gauge substrates more efficiently than standard self-drilling points, reducing installation time and extending tool life.

What is the recommended socket size for installation?

Select a hex socket that fits the hex head flange precisely. Using the correct socket size prevents rounding of the hex corners and ensures positive engagement for torque transfer. Refer to the product specification for the exact hex size for the ST5.5 thread.

What material thickness can the ST5.5-24*50 screw accommodate?

The ST5.5-24 specification with 50mm length and 3# tail provides engagement for thicker material assemblies and heavier gauge substrates. The actual maximum material thickness depends on the drill point length and substrate hardness. Consult the technical datasheet for specific thickness recommendations.

What is the silver Dacromet coating and what are its benefits?

Silver Dacromet is a water-based zinc flake coating with a silver metallic finish that provides high corrosion resistance with extended salt spray protection. It offers an attractive silver appearance suitable for visible applications while maintaining the corrosion protection properties of standard Dacromet.

Is this screw suitable for outdoor applications?

Yes. The SUS410 stainless steel material combined with silver Dacromet coating provides corrosion resistance for outdoor applications. The coating offers salt spray protection suitable for structural steel, infrastructure, and other applications exposed to weather conditions.

What is the recommended installation speed for this screw?

Install at controlled speeds to avoid overheating the extended drill point. The 3# tail requires appropriate speed management to maintain drilling efficiency. Use torque-controlled drivers to prevent over-tightening when the flange contacts the workpiece surface.

Installation Considerations

Select the correct hex socket size for the flange head to prevent rounding and ensure positive torque transmission during installation.

The 3# tail provides enhanced drilling capability for thicker materials. Adjust speed and feed rate accordingly to maximize drill point life and penetration efficiency.

Use torque-controlled installation tools to prevent over-driving. The flange should seat against the workpiece surface without distorting the flange or surrounding material.

Apply appropriate spindle speed based on material hardness; excessive speed may reduce drill point life and cause thermal damage to the silver Dacromet coating.

Ensure perpendicular alignment between screw axis and workpiece surface to prevent drill point deflection and ensure clean hole formation.

The silver Dacromet coating provides corrosion resistance and aesthetic finish. Handle screws with clean gloves to maintain coating integrity and prevent contamination.