The DIN 965 flat head bolt — formally classified as a cross-recessed countersunk flat head machine screw with metric thread — is one of the most widely specified flush-mount fasteners in global manufacturing. Its defining geometry is a 90° countersunk cone head combined with a Phillips (Type H) or Pozidriv (Type Z) cross recess, enabling reliable torque transmission through a standard cross-head driver in both manual and automated assembly environments.
Standardised by the German Institute for Standardization (Deutsches Institut für Normung), the DIN 965 designation has become a benchmark reference in industrial procurement across Europe, Asia, and North America. Engineers frequently treat it as interchangeable with ISO 7046-1 (Phillips recess) and ISO 7046-2 (Pozidriv recess) within stated tolerance bands — though DIN 965 remains the more commonly cited designation in B2B fastener procurement worldwide.
Figure 1: DIN 965 flat head bolt key dimensions — dk (head diameter), k (head height), l (nominal length), and 90° cone angle.
As a global hardware and fasteners supplier, Zhejiang Jiaxing Tuyue Import and Export Co., Ltd. manufactures and exports DIN 965 bolts to clients across more than 50 countries, maintaining full dimensional and mechanical compliance with the standard. The company holds ISO 9001 certification and operates from Jiaxing, Zhejiang Province, China — a region historically recognized as a major fastener manufacturing hub.
DIN 965 bolts are produced in metric coarse thread series per ISO 68-1. The standard nominal diameter range runs from M2 through M10, with M3, M4, M5, M6, and M8 accounting for the highest commercial volume. Standard coarse thread pitches are: M3×0.5, M4×0.7, M5×0.8, M6×1.0, M8×1.25, and M10×1.5. Fine-pitch variants exist but are treated as custom production items rather than stock catalogue entries.
The countersunk head angle is 90° ± 1° measured between opposing flanks of the cone. The head diameter (dk) and head height (k) maintain a fixed proportional relationship per nominal diameter. Representative values for the medium tolerance class:
| Nominal Dia. | Pitch (mm) | dk — Head Ø (mm) | k — Head Height (mm) | Length Range (mm) |
|---|---|---|---|---|
| M3 | 0.5 | 6.0 | 1.7 | 5 – 30 |
| M4 | 0.7 | 8.0 | 2.2 | 6 – 40 |
| M5 | 0.8 | 10.0 | 2.7 | 8 – 50 |
| M6 | 1.0 | 12.0 | 3.3 | 10 – 60 |
| M8 | 1.25 | 16.0 | 4.4 | 12 – 70 |
| M10 | 1.5 | 20.0 | 5.5 | 16 – 80 |
DIN 965 H specifies a Phillips (Type H) recess per ISO 4757. DIN 965 Z specifies a Pozidriv (Type Z) recess, also per ISO 4757. The recess depth and form directly influence cam-out resistance: Pozidriv offers measurably improved torque transmission and is favoured in automated assembly lines and applications requiring repeated fastening cycles. The correct driver size per nominal diameter is:
| Diameter | Phillips (PH) | Pozidriv (PZ) |
|---|---|---|
| M3 – M4 | PH1 | PZ1 |
| M5 – M6 | PH2 | PZ2 |
| M8 – M10 | PH3 | PZ3 |
Thread tolerances conform to ISO 965-1, tolerance class 6g for the external thread. Straightness and surface finish are inspected per ISO 4759-1 (tolerances for fasteners).
Figure 2: Relative salt spray corrosion resistance by DIN 965 material/coating type (indicative comparison, ISO 9227 basis).
Low-carbon steel (equivalent to AISI 1010–1018 or Chinese GB Q235/Q345 grades) is the base material for standard-grade DIN 965 bolts. Cold heading followed by thread rolling produces consistent grain flow and reliable mechanical properties. Property class 4.8 is the most common designation for plain carbon steel DIN 965 bolts. Property class 8.8 is achievable with medium-carbon steel subject to quench and temper heat treatment, covering applications requiring tensile strengths above 800 MPa.
Austenitic grades A2 (AISI 304) and A4 (AISI 316) dominate the corrosion-resistant segment. A2 provides adequate resistance in indoor or mildly humid environments; A4 is specified for marine, chemical processing, and outdoor structural applications where chloride exposure is a design concern. Tuyue's stainless steel bolt nut screws washers range includes DIN 965 in A2-70 and A4-70 property classes, both delivering a minimum tensile strength of 700 MPa.
Brass variants serve electrical and decorative applications where conductivity or aesthetic finish is critical. Aluminium DIN 965 bolts offer weight reduction benefits relevant to aerospace-adjacent and consumer electronics assemblies where mass budgets are tightly managed.
Coating selection directly affects corrosion resistance, dimensional envelope, friction coefficient, and regulatory compliance (particularly RoHS and REACH directives). The principal options for DIN 965 bolts are summarised below:
The most widely specified coating for carbon steel DIN 965. Coating thickness typically runs 5–12 µm. Yellow chromate passivation adds sacrificial protection; black passivation is used for visual differentiation and moderate corrosion resistance. Salt spray performance: approximately 72–120 hours per ISO 9227.
Produces a thicker zinc layer (45–85 µm), suitable for prolonged outdoor exposure. Because the coating adds significant material to the thread form, thread tolerances must be adjusted prior to galvanising. Not typically used for small-diameter DIN 965 screws due to thread fill risk.
A water-based zinc-aluminium flake coating offering approximately six times the salt spray resistance of standard electroplating, with zero hydrogen embrittlement risk. Preferred in automotive sub-assemblies and under-hood environments where hydrogen embrittlement of high-strength bolts is a concern.
Applied for decorative or mild corrosion-resistant finishes. Common in consumer electronics and furniture hardware where a bright metallic appearance is specified alongside moderate protection requirements.
A conversion coating that improves oil retention, used as a pre-assembly lubricant carrier and corrosion inhibitor for indoor applications. Provides a matte dark-grey finish and is a standard pre-treatment choice in automotive assembly.
Supplied without surface treatment for applications where the engineer specifies a proprietary coating process post-machining, or for non-corrosive indoor environments where economy is the primary driver.
Property class defines mechanical performance independently of material family. Hardness values for carbon steel grades are specified in ISO 898-1; for stainless steel grades in ISO 3506-1.
| Property Class | Material | Min. Tensile Str. (MPa) | Min. Yield / 0.2% Proof (MPa) | Elongation (%) |
|---|---|---|---|---|
| 4.8 | Carbon steel | 420 | 340 | ≥ 14 |
| 8.8 | Med. carbon, Q&T | 800 | 640 | ≥ 12 |
| A2-70 | SS 304 | 700 | 450 | ≥ 11 |
| A4-70 | SS 316 | 700 | 450 | ≥ 11 |
The production quality of a DIN 965 bolt is determined largely by the precision and control of four sequential processes: cold heading, thread rolling, heat treatment, and surface finishing.
Wire Drawing & Cold Heading — Wire rod is drawn to precise diameter and fed into a cold heading machine. The countersunk head profile is struck under high tonnage in a single or progressive die stroke. Cold heading work-hardens the material, enhancing tensile and fatigue performance versus machined equivalents.
Thread Rolling — Threads are produced by displacing material between hardened dies rather than cutting it. Rolled threads yield superior root radius profile, compressive residual stresses, and fatigue resistance. All standard DIN 965 production at Tuyue uses thread rolling per industry best practice.
Heat Treatment (Class 8.8 and above) — Property class 8.8 requires quench and temper treatment. Carbon content, quenching medium, tempering temperature, and duration are controlled within tight process windows and verified by in-house hardness testing to ISO 898-1 thresholds.
Surface Treatment — Electroplating lines, Dacromet application equipment, and phosphating tanks operate under process sheets referencing ASTM, ISO, and internal QC specifications. Salt spray testing per ISO 9227 / ASTM B117 is conducted on sampled lots before release.
Figure 3: Simplified manufacturing flow for DIN 965 flat head bolts — from wire drawing to finished surface treatment.
DIN 965 is the primary standard, but several equivalent or closely related specifications are encountered in international engineering documentation:
| Standard | Body | Description | Notes |
|---|---|---|---|
| DIN 965 | DIN (Germany) | Cross-recessed countersunk flat head screw, metric | Primary procurement reference |
| ISO 7046-1 | ISO | Type H (Phillips) cross recess, Product Grade A | Interchangeable within tolerances |
| ISO 7046-2 | ISO | Type Z (Pozidriv) cross recess, Product Grade A | Interchangeable within tolerances |
| ASME B18.6.3 | ASME (USA) | Flat head machine screw, unified inch thread | Different dimensional series |
| JIS B 1111 | JIS (Japan) | Cross-recessed countersunk head screw | Near-identical geometry to DIN 965 |
| ISO 15065 | ISO | Countersunk flat head, hexalobular (Torx) recess | Not DIN 965 — frequently confused |
When international procurement documents reference DIN 965, ISO 7046, or both simultaneously, Tuyue's technical team verifies which dimensional series takes precedence and aligns production accordingly. Detailed product specifications are available across the full fastener range on the Tuyue website.
The receiving material must be pre-drilled and countersunk to the correct angle (90°) and diameter. An undersized countersink forces the screw head above the surface and creates stress concentrations; an oversized countersink causes the head to sink below flush and reduces clamping efficiency. Countersink cutters with 90° included angle are widely available. The recommended countersink diameter equals the dk value of the selected screw size per the DIN 965 dimensional table.
| Nominal Diameter | Recommended Torque (N·m) |
|---|---|
| M4 | 2.5 |
| M5 | 5.0 |
| M6 | 8.5 |
| M8 | 20.0 |
Standard DIN 965 bolts do not incorporate locking features. Where vibration resistance is required, specify a thread-locking adhesive (medium-strength, e.g., threadlocker compounds in the 200–300 cP viscosity range), a nylon patch pre-applied to the thread form, or pair with a spring lock washer. For high-vibration assemblies, contact Tuyue's engineering team for fastener selection guidance via the company contact page.
