DIN 603 Carriage Bolts
| Standard | DIN 603 |
|---|---|
| Material | Carbon Steel / Alloy Steel |
| Strength Grade | 4.6 / 4.8 / 8.8 |
| Size Range | M5-M20 |
| Surface Treatment | Plain / Zinc Plated / Hot Dip Galvanized |
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Product Description
Product Description & Key Specifications
DIN 603 carriage bolts use a smooth domed head with a square neck directly beneath it. The square neck bites into timber or locates in a matching square hole, preventing the bolt from turning while the nut is tightened from the opposite side.
The range covers M5-M20 in carbon and alloy steel, with property classes 4.6, 4.8 and 8.8 selected according to joint load. Plain, zinc-plated and hot-dip-galvanized finishes support indoor fabrication, general construction and exposed timber or steel assemblies.
Specify diameter, overall length, threaded length, square-neck dimensions, property class and finish in the RFQ. ISO 8677 may appear as a historical comparison, but substitution should be confirmed against the required edition, dimensions and drawing rather than assumed from the standard number.
| Product type | Round head square neck bolt / carriage bolt / coach bolt |
|---|---|
| Standard | DIN 603 |
| Material | Carbon steel / alloy steel |
| Property class | 4.6 / 4.8 / 8.8 |
| Size range | M5-M20 |
| Thread | Metric coarse thread; threaded length according to size and order |
| Head and neck | Smooth round head with square anti-rotation neck |
| Surface finish | Plain / zinc plated / hot dip galvanized |
| Matching hardware | Metric hex nuts and flat washers selected by class and coating |
| Inspection documents | CoC, MTC, dimensional and coating reports on request |
Dimensions & SpecificationsDIN 603
Technical Drawing
Dimensional Table
| Parameter | M5 | M6 | M8 | M10 | M12 | M16 | M20 |
|---|---|---|---|---|---|---|---|
| P | 0.8 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2.5 |
| dk/max | 13.55 | 16.55 | 20.65 | 24.65 | 30.65 | 38.8 | 46.8 |
| dk/min | 12.45 | 15.45 | 19.35 | 23.35 | 29.35 | 37.2 | 45.2 |
| ds/max | 5 | 6 | 8 | 10 | 12 | 16 | 20 |
| ds/min | 4.52 | 5.52 | 7.42 | 9.42 | 11.3 | 15.3 | 19.16 |
| k1/max | 4.1 | 4.6 | 5.6 | 6.6 | 8.75 | 12.9 | 15.9 |
| k1/min | 2.9 | 3.4 | 4.4 | 5.4 | 7.25 | 11.1 | 14.1 |
| k/max | 3.3 | 3.88 | 4.88 | 5.38 | 6.95 | 8.95 | 11.05 |
| k/min | 2.7 | 3.12 | 4.12 | 4.62 | 6.05 | 8.05 | 9.95 |
| r/max | 0.5 | 0.5 | 0.5 | 0.5 | 1 | 1 | 1 |
| s/max | 5.48 | 6.48 | 8.58 | 10.58 | 12.7 | 16.7 | 20.84 |
| s/min | 4.52 | 5.52 | 7.42 | 9.42 | 11.3 | 15.3 | 19.16 |
Engineering references
Technical resources
Review the applicable dimensions, drawing and standard relationship before confirming the ordered specification.02
Selection
Selection Advantages by Application
Timber framing and construction joints
The square neck embeds into timber to resist rotation, while the smooth round head leaves a low-profile exposed surface on fences, decks, frames and structural timber assemblies.
Construction and infrastructure fastenersSteel plates, guards and brackets
A correctly sized square or formed hole locates the neck in sheet or plate assemblies, allowing installation where the head side is difficult to hold with a tool.
Industrial equipment fasteners03
Assembly
Recommended Matching Products
04
Manufacturing
Manufacturing & Quality Control
Manufacturing CapabilityQuality Control
Cold or hot forming of domed head and square neckHead diameter, head height and square-neck dimensional inspection
Metric thread rolling from M5 to M20GO/NO-GO thread gauging and threaded-length verification
Property classes 4.6, 4.8 and 8.8Material traceability, hardness and mechanical-property verification as specified
Plain, zinc-plated or hot-dip-galvanized finishCoating thickness, appearance and nut-fit inspection
Bulk or project-kit packaging with nuts and washersLot identification, quantity and matching-component checks
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FAQ
Common Questions Before RFQ
What stops a DIN 603 carriage bolt from turning?
The square neck beneath the head embeds in timber or fits a matching square hole, resisting rotation while the nut is tightened.
Can DIN 603 carriage bolts be supplied in property class 8.8?
Yes. Class 8.8 is available for higher-load joints when the required dimensions, heat treatment, testing and finish are confirmed in the order.
Are DIN 603 bolts fully threaded?
Threaded length varies with diameter and overall length. State the required grip and threaded length, especially when the joint must keep threads out of the shear plane.
Can carriage bolts be hot-dip galvanized?
Yes. HDG is common for exposed construction and timber work, but coating allowance and thread fit must be coordinated with a compatible galvanized nut.
Is ISO 8677 automatically interchangeable with DIN 603?
No automatic interchangeability should be assumed. Confirm the applicable edition, head and neck geometry, thread, tolerances and drawing before substitution.
Need DIN 603 carriage bolts for a timber or steel project?
Send the diameter, length, property class, finish, quantity and nut or washer requirements. Include the drawing or required square-neck dimensions for critical assemblies.
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