DIN 7504 Self-Drilling Screws — K/N/O/P Spec Guide for Die Manufacturers
DIN 7504 reference for drill point die production: K-type (hex washer head), N-type, O-type (countersunk), and P-type head geometries with drill point dimensions, IFI size mapping, and matching L1–L6 die specifications.
Understanding the DIN 7504 Standard Family
DIN 7504 is the German standard for self-drilling tapping screws. It defines four main types based on head style and application, each with specific drill point geometry requirements that directly determine die specifications.
Standards note: DIN 7504 has been formally superseded by ISO 10666, ISO 15480, ISO 15481, ISO 15482, and ISO 15483. However, DIN 7504 designations (particularly DIN 7504-K) remain the most widely used commercial references in European, Middle Eastern, and many Asian markets. This guide uses DIN 7504 terminology because it is what most buyers and suppliers still reference in practice.
DIN 7504 Types at a Glance
| Standard | Head Type | Drive | Primary Application |
|---|---|---|---|
| DIN 7504-K | Hex washer head | Hex socket | Metal roofing, cladding, general steel |
| DIN 7504-N | Pan head | Phillips/Pozidrive | Sheet metal assembly, HVAC, enclosures |
| DIN 7504-O | Countersunk head | Phillips/Pozidrive | Flush-mount applications, trim panels |
| DIN 7504-P | Truss/mushroom head | Phillips/Pozidrive | Large bearing surface, thin sheet overlap |
Size Designations and Dimensions
DIN 7504 uses the ST (Self-Tapping) size designation system. The following table lists the standard dimensional values per DIN 7504:
| ST Size | Nominal Ø (mm) | Thread Pitch (mm) | Approximate IFI Equivalent |
|---|---|---|---|
| ST 2.9 | 2.9 | 1.3 | #4 |
| ST 3.5 | 3.5 | 1.3 | #6 |
| ST 3.9 | 3.9 | 1.3 | #7 |
| ST 4.2 | 4.2 | 1.4 | #8 |
| ST 4.8 | 4.8 | 1.6 | #10 |
| ST 5.5 | 5.5 | 1.8 | #12 |
| ST 6.3 | 6.3 | 1.8 | #14 |
Drill Point Requirements per DIN 7504
The standard specifies drill point geometry that must be achieved by the drill point die:
Point Length (per DIN 7504)
The drill point length must be sufficient to clear the target material before the thread engages. DIN 7504 defines minimum point lengths based on the maximum steel thickness to be drilled:
| Drilling Capacity | Point Length (min) | Thread-Free Zone (min) |
|---|---|---|
| Up to 0.9mm steel | Short point | 2 × material thickness |
| 0.9–2.0mm steel | Medium point | 2 × material thickness |
| 2.0–5.0mm steel | Long point | 2 × material thickness |
| 5.0–12.5mm steel | Extra-long point | 2 × material thickness |
Drill Diameter (per DIN 7504)
The drill point diameter (measured at the widest point of the flutes) must be larger than the screw's root diameter to create a clearance hole:
| ST Size | Screw Root Ø (mm) | Min Drill Ø (mm) | Max Drill Ø (mm) |
|---|---|---|---|
| ST 2.9 | 2.01 | 2.2 | 2.3 |
| ST 3.5 | 2.43 | 2.7 | 2.9 |
| ST 3.9 | 2.73 | 2.9 | 3.2 |
| ST 4.2 | 2.95 | 3.1 | 3.6 |
| ST 4.8 | 3.33 | 3.7 | 4.1 |
| ST 5.5 | 3.99 | 4.2 | 4.7 |
| ST 6.3 | 4.54 | 5.1 | 5.5 |
Flute Geometry
- Number of flutes: 2 (standard for all DIN 7504 types, per the standard)
- Flute depth: Must allow complete chip evacuation
- Point angle: 130°–140° (common industry practice — not explicitly standardized in DIN 7504)
- Concentricity: ≤ 0.05mm TIR (total indicated runout) — a widely accepted practical target
Note: The point angle and concentricity values above are common design recommendations, not DIN 7504 requirements. Consult the applicable standard version for mandatory dimensions.
Mapping DIN 7504 to ZLD Die Series
| ST Size | DIN 7504 Type | Drill Ø Range | ZLD Die Series | Die Codes |
|---|---|---|---|---|
| ST 2.9 | K/N/O/P | 2.2–2.3mm | L1 | L1-22, L1-23 |
| ST 3.5 | K/N/O/P | 2.7–2.9mm | L1 | L1-27 to L1-29 |
| ST 3.9 | K/N/O/P | 2.9–3.2mm | L1 | L1-29 to L1-32 |
| ST 4.2 | K/N/O/P | 3.1–3.6mm | L1 | L1-31 to L1-36 |
| ST 4.8 | K/N/O/P | 3.7–4.1mm | L2 | L1-37 to L1-41 |
| ST 5.5 | K/N/O | 4.2–4.7mm | L3–L4 | L1-42 to L1-47 |
| ST 6.3 | K | 5.1–5.5mm | L5–L6 | L1-51 to L1-55 |
Testing Requirements
DIN 7504 specifies performance testing for finished screws:
Drilling Performance Test (per DIN 7504)
- Test plate: Steel plate of specified thickness and hardness
- Driving speed: Typically 2,500 RPM
- Applied force: Gravity or controlled axial load
- Pass criteria: Complete penetration within specified time, no visible drill point damage
Actual test parameters and pass/fail criteria should follow the specific DIN 7504 edition applicable to your production. The values above summarize common test conditions.
Torsional Strength Test (per DIN 7504)
- Method: Apply increasing torque until failure
- Minimum torque values are specified per size in the standard:
| ST Size | Min Torsional Strength (Nm) |
|---|---|
| ST 2.9 | 1.5 |
| ST 3.5 | 2.8 |
| ST 4.2 | 5.0 |
| ST 4.8 | 7.5 |
| ST 5.5 | 12.0 |
| ST 6.3 | 18.0 |
DIN 7504 vs IFI: Key Differences
| Aspect | DIN 7504 | IFI |
|---|---|---|
| Size system | ST (metric) | # (inch-based) |
| Head types | 4 types (K/N/O/P) | Multiple types |
| Testing | DIN-specific procedures | SAE J78 |
| Market | Europe, Middle East, Asia | Americas, some Asia |
| Material grades | Per DIN/ISO standards | Per SAE/IFI standards |
For die manufacturers serving global markets, both standards are generally supported. The drill point geometry is functionally similar, though the standards differ in test methods, tolerances, and material requirements — not just naming conventions.
Source DIN 7504-Compatible Dies
ZLD Precision Mold manufactures drill point dies compatible with all DIN 7504 types. Our L1–L6 series covers the complete ST 2.9 through ST 6.3 range — check the specification table for the size and geometry that matches your screw standard.