Allen CSK Screw
What are Allen CSK Screws?
Allen CSK (Countersunk) screws are precision-engineered fasteners featuring a flat head with a hexagonal socket drive. Designed to sit flush with or below the surface of the material they’re installed into, these screws provide a neat, low-profile finish—ideal for applications where aesthetics and a snag-free surface are important.
Allen CSK screws are widely used in furniture, electronics, aerospace, and machine assemblies where flush-mounting and high-torque fastening are essential.
Key Features
High
Grip
Durable
Construction
Easy Installation
& Removal
Wide
Compatibility
Corrosion
Resistant
Specifications
| Specification Category | Parameter / Feature | Details / Options |
|---|---|---|
| Size Range | Nominal Size | M3 to M36 (custom sizes available) |
| Length Range | 6 mm to 500 mm (depending on diameter) | |
| Pressure Ratings | ANSI / ASME Class | Class 150, 300, 600, 900, 1500, 2500 (when used in pressure-retaining assemblies) |
| PN Ratings | PN6, PN10, PN16, PN25, PN40, PN64 | |
| Product Types | CSK Screws Variants | Countersunk Socket Head Screws, Flat Head Socket Screws |
| Head Angle | Standard 90° (82° & 100° available on request) | |
| Thread Types | Metric Coarse, Metric Fine, UNC, UNF | |
| Material Options | Carbon Steel | Grades 8.8, 10.9, 12.9 |
| Stainless Steel | A2-70, A4-70, A4-80 | |
| Alloy Steel | Quenched & Tempered | |
| Other Alloys | Brass, Titanium, Duplex Stainless Steel, Inconel | |
| Standards & Certifications | ASTM | ASTM F835, ASTM F912 |
| ASME / ANSI | ASME B18.3 | |
| ISO / DIN | ISO 10642, DIN 7991 | |
| Certifications | ISO 9001, PED 2014/68/EU, NACE MR0175, RoHS, CE | |
| Design Features | Head Type | Flat / Countersunk with hexagonal socket drive |
| Drive Type | Hex Socket (Allen Key) | |
| Tolerance | As per ISO 4759 / ASME B18.3 | |
| Thread Fit | 6g / UNC-2A, UNF-2A | |
| Coating & Surface Finish | Anti-Corrosion Coating | Zinc Plated, Black Oxide, Hot Dip Galvanized |
| Optional Coatings | PTFE, Geomet, Dacromet, Anodized (for Aluminium/Titanium) | |
| Surface Finish | Polished, Self-Colored, Passivated | |
| Testing & Inspection | Mechanical Testing | Tensile, Proof Load, Hardness, Wedge Tensile |
| Non-Destructive Testing | Magnetic Particle (MPI), Dye Penetrant (DPT), Ultrasonic (UT) | |
| Dimensional Inspection | GO/NO-GO Gauges, Micrometer Verification |
Dimensions
| Nominal Size (M) | Thread Pitch (mm) | Head Diameter (dk, mm) | Head Height (k, mm) | Countersink Angle (°) | Socket Size (s, mm) | Min. Thread Length (b, mm) |
|---|---|---|---|---|---|---|
| M3 | 0.5 | 6.0 | 1.7 | 90° | 2.0 | 18 |
| M4 | 0.7 | 8.0 | 2.3 | 90° | 2.5 | 20 |
| M5 | 0.8 | 10.0 | 2.8 | 90° | 3.0 | 22 |
| M6 | 1.0 | 12.0 | 3.3 | 90° | 4.0 | 24 |
| M8 | 1.25 | 16.0 | 4.4 | 90° | 5.0 | 28 |
| M10 | 1.5 | 20.0 | 5.5 | 90° | 6.0 | 32 |
| M12 | 1.75 | 24.0 | 6.6 | 90° | 8.0 | 36 |
| M16 | 2.0 | 30.0 | 8.8 | 90° | 10.0 | 44 |
| M20 | 2.5 | 37.0 | 11.0 | 90° | 12.0 | 52 |
| M24 | 3.0 | 44.0 | 13.2 | 90° | 14.0 | 60 |
| M30 | 3.5 | 56.0 | 16.5 | 90° | 17.0 | 72 |
| M36 | 4.0 | 66.0 | 19.8 | 90° | 22.0 | 84 |
Mechanical Properties
| Property | Value | Unit / Standard |
|---|---|---|
| Tensile Strength | 600 – 1,200 | MPa |
| Yield Strength | 400 – 1,100 | MPa |
| Hardness | 320 – 390 | HV |
| Elongation | ≥ 10 – 18 | % |
| Density | 7.8 | g/cm³ |
| Impact Toughness | ≥ 20 – 50 | J |
| Modulus of Elasticity (E) | ~200 | GPa |
| Fatigue Strength | 240 – 480 | MPa |
| Corrosion Resistance | Good to Excellent | – |
| Thermal Conductivity | 15 – 50 | W/m·K |
| Coefficient of Thermal Expansion | 11 – 17 ×10⁻⁶ | /°C |
| Yield Ratio (YS/UTS) | 0.4 – 0.9 | – |
| Poisson’s Ratio | 0.27 – 0.30 | – |
| Brinell Hardness Range | 320 – 390 | HB |
| Surface Finish | Serrated / Stock / Smooth finish | – |
| Head Type | Countersunk (CSK) | – |
| Drive Type | Allen / Hex Socket | – |
| Operating Temperature Range | -40 to 150 | °C |
| Coating Options | Zinc, Black Oxide, Nickel Plating, PTFE | – |
| Proof Load | 450 – 1,050 | MPa |
Chemical Composition
| Element | SS 304 (%) | SS 304L (%) | SS 316 (%) | SS 316L (%) |
|---|---|---|---|---|
| Chromium (Cr) | 18.0 – 20.0 | 18.0 – 20.0 | 16.0 – 18.0 | 16.0 – 18.0 |
| Nickel (Ni) | 8.0 – 10.5 | 8.0 – 12.0 | 10.0 – 14.0 | 10.0 – 14.0 |
| Carbon (C) | ≤ 0.08 | ≤ 0.03 | ≤ 0.08 | ≤ 0.03 |
| Manganese (Mn) | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 | ≤ 2.00 |
| Silicon (Si) | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 | ≤ 1.00 |
| Phosphorus (P) | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
| Sulfur (S) | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 | ≤ 0.030 |
| Iron (Fe) | Balance | Balance | Balance | Balance |
| Molybdenum (Mo) | — | — | 2.0 – 3.0 | 2.0 – 3.0 |
Applications of Allen CSK Screws
Construction &
Infrastructure
Automotive & Heavy
Equipment
Manufacturing &
Fabrication
Medical & Laboratory
Equipment
Electrical &
Electronics Assembly
Oil, Gas & Petrochemical
Installations
Do you have questions?
What does CSK mean in Allen CSK screws?
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