Combination screws are essential fasteners widely used in construction, automotive, and machinery industries. They combine multiple functional features, such as a threaded shank with a washer or a specialized head, making them efficient for high-stress applications.

In this guide, we’ll explore:

• What combination screws are

• Different types and their uses

• Key materials and coatings

• How to select the right combination screw for your project

1. What Are Combination Screws?

Combination screws (or combo screws) are multi-functional fasteners that integrate two or more components—typically a screw with an attached washer or a self-locking feature. They reduce assembly time, improve load distribution, and enhance vibration resistance.

Key Features:

✔ Integrated Washer: Eliminates the need for a separate washer.
✔ Self-Sealing: Some variants include rubber gaskets for waterproofing.
✔ High-Strength Materials: Often made from stainless steel, alloy steel, or brass.

2. Types of Combination Screws & Their Applications

Different industries require specific screw types. Below is a breakdown of the most common combination screws:

2.1. Hex Washer Head Combination Screws

• Design: Hex head with an integrated flat washer.

• Applications: Automotive panels, sheet metal assemblies.

• Advantages: Prevents loosening under vibration.

2.2. Trim Head Combination Screws

• Design: Low-profile head with a built-in washer.

• Applications: Woodworking, cabinetry, and decking.

• Advantages: Reduces surface damage.

2.3. Self-Drilling Combination Screws

• Design: Sharp drill point with a washer head.

• Applications: Metal roofing, HVAC installations.

• Advantages: No pre-drilling required.

Comparison Table: Common Combination Screw Types

3. Material & Coating Selection for Durability

Choosing the right material ensures longevity and performance.

3.1. Common Materials

• Stainless Steel (Grade 304/316): Corrosion-resistant, ideal for outdoor use.

• Alloy Steel (Grade 8.8/10.9): High tensile strength for heavy machinery.

• Brass: Decorative and corrosion-resistant for electrical components.

3.2. Protective Coatings

• Zinc Plating: Basic corrosion resistance.

• Hot-Dip Galvanizing: Extreme rust protection for marine environments.

• Dacromet Coating: High-temperature resistance.

4. How to Select the Right Combination Screw

4.1. Load & Stress Requirements

• Shear Load: Use alloy steel screws.

• Vibration Resistance: Opt for nylon-insert locking screws.

4.2. Environmental Conditions

• Humid/Salty Air: Stainless steel or galvanized screws.

• High Temperatures: Ceramic-coated or Dacromet-treated screws.

4.3. Industry Standards

Ensure compliance with:

• DIN (German Industrial Standards)

• ISO (International Standards Organization)

• ASTM (American Society for Testing and Materials)

5. Conclusion

Combination screws offer efficiency and reliability for industrial applications. By understanding their types, materials, and selection criteria, you can optimize fastener performance in your projects.

Need high-quality combination screws for your next project? Click"contact us"!