🔩 Product Overview: Grade 12.9 Torx Countersunk Machine Screws – SCM435 Alloy Steel (M3–M5)
When your project demands the highest level of strength and reliability, standard fasteners won't cut it. These Grade 12.9 Torx countersunk machine screws are made from SCM435 alloy steel, hardened and tempered to deliver exceptional tensile strength and wear resistance. The internal Torx (six‑lobe) drive provides superior torque transfer with zero cam‑out, while the flat countersunk head sits flush for a smooth, professional finish. Fully threaded with standard metric coarse pitch, available in M3, M4, and M5 diameters with lengths from 4mm to 16mm (measured under the head). Galvanized surface treatment adds corrosion resistance. Perfect for CNC machine tools, tool holders, heavy machinery, automotive, and any high‑stress industrial application.
✨ Why These Grade 12.9 Torx Screws Are Built for Demanding Applications
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Grade 12.9 high tensile strength – Ultra‑high hardness and excellent wear resistance. Withstands extreme loads and repeated use without failure.
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SCM435 alloy steel construction – Chromium‑molybdenum alloy steel, hardened and tempered for superior mechanical properties.
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Internal Torx (six‑lobe) drive – Eliminates cam‑out, distributes torque evenly, and allows precise tightening without damaging the recess.
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Countersunk flat head (90°) – Sits flush in tapered holes for a snag‑free, professional finish – ideal for tooling and machine assemblies.
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Fully threaded, coarse metric pitch – Standard threads: M3x0.5, M4x0.7, M5x0.8. Threads run the entire shank length for maximum grip.
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Galvanized surface treatment – Provides rust protection and long service life in various working environments.
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Precision CNC machining – Stable dimensions, smooth burr‑free surface, and easy installation.
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Wide industrial applications – CNC machine tools, tool holders, lathes, mechanical assembly, mold fixing, automotive, motorcycle, and precision engineering.
📏 Technical Specifications – Grade 12.9 Torx Countersunk Screws (M3–M5)
| Specification |
Details |
| Product Type |
Torx Countersunk Flat Head Machine Screws (Six‑lobe drive) |
| Grade |
12.9 (high tensile strength) |
Material |
SCM435 Alloy Steel (Cr‑Mo alloy)
|
| Drive Style |
Internal Torx (six‑lobe) – use T10 for M3, T20 for M4, T25 for M5 (approx.) |
| Head Style |
Countersunk flat head (90°) |
| System of Measurement |
Metric |
| Thread Sizes (Diameter) |
M3, M4, M5 |
| Thread Pitch (coarse) |
M3x0.5, M4x0.7, M5x0.8 |
| Thread Type |
Fully threaded |
| Length Range (under head) |
4mm – 16mm (select from options; typical: 4, 5, 6, 8, 10, 12, 14, 16mm) |
| Surface Finish |
Zinc plated (galvanized) – corrosion resistant |
| Packaging |
Plastic bag / cardboard box |
❓ FAQs – Grade 12.9 Torx Countersunk Screws
🔸 What makes Grade 12.9 screws stronger than standard Grade 8.8 or 10.9?
Grade 12.9 is the highest common metric strength class for steel screws. It has a tensile strength of 1220 MPa and a proof strength of 970 MPa – significantly higher than Grade 8.8 (640 MPa yield) and Grade 10.9 (830 MPa yield). The SCM435 alloy steel is heat‑treated for maximum hardness and durability, making these screws ideal for high‑stress industrial applications.
🔸 Are these screws fully threaded? How is length measured?
Yes – they are fully threaded from just under the head to the tip. Length is measured from the underside of the head (the flat bearing surface) to the tip, not including the head. For example, an M4 x 12mm screw has a 12mm threaded shank. This matches standard countersunk screw measurement.
🔸 What Torx bit size do I need for M3, M4, and M5?
Typical Torx sizes: M3 uses T10, M4 uses T20, M5 uses T25. Always check fit before applying torque – a quality Torx bit set (T6–T30) is recommended for these sizes.
🔸 Will galvanized coating prevent rust?
Zinc plating (galvanized) provides good corrosion resistance for indoor and light outdoor use. For constant moisture, saltwater, or chemical exposure, stainless steel would be a better choice. These screws are designed for industrial machinery and tooling environments where moderate humidity is present.
🔸 Can I use these screws with nuts, or are they for tapped holes only?
These are standard machine screws – they work with matching metric nuts (M3–M5) or in pre‑tapped holes. For full strength, use Grade 10 or higher nuts to match the 12.9 screw strength.
🔸 What are the typical applications for Grade 12.9 countersunk screws?
CNC machine tools, tool holders, lathe turrets, mold fixtures, industrial machinery, heavy equipment assembly, automotive drivetrain components, motorcycle parts, and any high‑vibration or high‑load application where a flush finish is required.
