Metric coarse thread is the default choice in many industrial fastener orders. In the workshop, we see it every day on bolts, screws, nuts, studs, anchors, and threaded rods. It is easy to source, easy to assemble, and usually more tolerant of dirt or minor handling damage than fine thread.
Still, buyers should not write only “M12 bolt” on an RFQ. The pitch must be confirmed, especially when parts must match existing nuts, tapped holes, or imported equipment.
What Metric Coarse Thread Means
Metric thread is described by diameter and pitch. For example, M12 × 1.75 means a 12 mm nominal diameter and a 1.75 mm pitch.
When the pitch is not written, many suppliers assume standard coarse pitch. That works for common stock items, but it can create mistakes when the mating part uses fine thread.
For regular orders, buyers can review common attaches standards ou produits de boulons avant de confirmer la demande de prix.
Common Metric Coarse Thread Chart
| Taille métrique | Standard Coarse Pitch | Common Fastener Use |
|---|---|---|
| M3 | 0.5 mm | Small screws, light assemblies |
| M4 | 0.7 mm | Electrical parts, brackets |
| M5 | 0.8 mm | Machine screws, small equipment |
| M6 | 1.0 mm | Machines générales |
| M8 | 1.25 mm | Brackets, frames, equipment |
| M10 | 1.5 mm | Machinery and structural support |
| M12 | 1.75 mm | Equipment bases, steel parts |
| M16 | 2.0 mm | Heavy machinery, construction |
| M20 | 2.5 mm | Steel structures, large assemblies |
| M24 | 3.0 mm | Heavy-duty bolted joints |
| M30 | 3.5 mm | Large equipment and foundations |
| M36 | 4.0 mm | Anchors, structural connections |
This chart is useful for quoting and quick checking, but final production should still follow the required DIN, ISO, ASTM, EN, or drawing standard.
Fil grossier vs fil fin
When Coarse Thread Works Best
Coarse thread is usually preferred for:
- Assemblée générale industrielle
- Stock fastener supply
- Construction and maintenance work
- Parts exposed to dust or light corrosion
- Fast installation and field repair
Fine thread may be used when the design needs finer adjustment, thinner wall engagement, or specific OEM requirements. It should be clearly stated on the drawing or RFQ.
Erreurs courantes des acheteurs
The most common mistake is mixing coarse and fine thread parts in one order. M12 × 1.75 and M12 × 1.5 look close, but they will not assemble correctly.
Also check coating. Hot-dip galvanizing, zinc flake, and PTFE coating can affect thread fit. For coated products, review diverses attaches enduites and confirm nut assembly after finishing.
Liste de contrôle de la demande de prix
Before ordering metric coarse thread fasteners, provide:
- Diamètre et longueur
- Coarse pitch value
- Norme de produit
- Qualité du matériau et de la résistance
- Finition superficielle
- Matching nut or tapped hole requirement
- Quantité et emballage
For unusual thread length, special pitch, or drawing-based parts, use fixations non standard sur mesure.
Conseil final
Metric coarse thread is the safest starting point for many industrial fastener orders. But buyers should still confirm pitch, standard, material, grade, coating, and matching parts before production.
A clear thread specification prevents wrong-thread delivery, assembly delays, and unnecessary inspection disputes.