Flat Head Torx Screws — Metric Sizes
What Are Flat Head Torx Screws?
Flat head Torx screws, also known as countersunk Torx screws, feature an 82° or 90° conical underhead profile that allows the screw to sit flush with or below the surface of the mating material when installed in a countersunk hole. This eliminates any protruding head that could snag, interfere with mating parts, or present an unsightly finish.
The Torx (hexalobular) drive socket provides six points of engagement, enabling high torque application with reduced risk of cam-out. This is particularly valuable when driving into hardwood, composites, or metal where installation torque is high.
Key Features and Benefits
• Flush Installation: 82° countersunk head allows the fastener to sit level with or below the work surface.
• Torx Drive: Six-lobe engagement for high torque, cam-out resistance, and extended tool life.
• Wide Application Range: Suitable for woodworking, furniture, electronics, aerospace, and general metalwork.
• Clean Aesthetic Finish: Ideal for visible surfaces in consumer products and architectural metalwork.
• High Strength Options: Available in Grade 8.8 and 10.9 alloy steel for structural applications.
Materials and Finishes
• Alloy Steel (Grade 8.8 / 10.9) — Zinc Plated or Black Oxide: For high-strength structural applications.
• Stainless Steel (A2 / A4): For corrosion-critical or aesthetic applications.
Standards Compliance
• DIN 965 — Countersunk flat head screws
• ISO 14581 — Hexalobular socket countersunk flat head screws
Size Range and Availability
Available in M3 through M12, with lengths from 5mm to 60mm.
Frequently Asked Questions (FAQs)
1. What angle is the countersink for flat head Torx screws?
Standard metric flat head Torx screws have an 82° countersink angle conforming to DIN 965 / ISO 14581.
2. What is the benefit of a Torx drive over a Phillips drive on a countersunk screw?
Torx provides significantly better torque transfer and virtually eliminates cam-out — a common problem with Phillips drives when flush-seating countersunk screws at high torque.
3. Can flat head Torx screws be used in wood?
Yes — they are popular in cabinetry and furniture making because the flush head eliminates snagging and creates a clean finish.
4. Do I need a countersink bit before installing these?
Yes — a countersunk pilot hole matching the screw's head angle is required for a proper flush installation.
5. Are flat head Torx screws suitable for metal-to-metal fastening?
Yes — in alloy steel grades 8.8 or 10.9, they are suitable for structural metal applications, including machine frames and brackets.
6. What is the difference between DIN 965 and ISO 14581?
They specify the same countersunk head geometry. DIN 965 is the German standard; ISO 14581 is the international equivalent for hexalobular socket screws.
7. Can I use flat head Torx screws in composite panels?
Yes — they are widely used in composite and fibre-reinforced panels, particularly in aerospace and automotive interiors.
8. What Torx bit size fits an M5 flat head screw?
An M5 flat head Torx screw typically uses a T25 Torx driver bit. Always confirm with the product dimensional specifications.
9. Are stainless steel flat head Torx screws available?
Yes — A2 and A4 stainless steel variants are available for marine, outdoor, and food-processing environments.
10. What is the maximum tensile strength for Grade 10.9 flat head Torx screws?
Grade 10.9 alloy steel flat head screws have a minimum tensile strength of 1040 MPa.
