Que signifie 8.8 sur un boulon ? Guide de l'acheteur

Lorsque les acheteurs voient « 8.8 » sur une tête de boulon, il est facile de penser qu'il s'agit simplement d'une marque d'usine. Ce n'est pas. Pour les boulons métriques, 8.8 is a mechanical property class. It tells you the bolt’s strength level under the relevant metric fastener standard.

This marking is common on industrial bolts used in machinery, steel frames, brackets, equipment bases, and construction assemblies.

What 8.8 Means

The Two Numbers Explained

In simple terms, the first number shows the nominal tensile strength. The second number shows the yield ratio.

So, a class 8.8 bolt is stronger than low-grade general fasteners, but it is not the same as 10.9 or 12.9. It is also not the same as SAE Grade 8, which belongs to the inch fastener system.

Les acheteurs peuvent consulter les informations communes produits de boulons et attaches à haute résistance when comparing strength grades.

Where 8.8 Bolts Are Used

Class 8.8 bolts are widely used because they offer a strong balance of strength, availability, and cost.

Les applications courantes incluent :

• Bâtis de machines
• Supports en acier
• Bases d'équipement
• Quincaillerie de construction
• Machines agricoles
• Assemblages industriels généraux
• Medium-load structural connections

For many standard industrial jobs, 8.8 is enough. For higher-load or compact assemblies, buyers may need 10.9 or 12.9 instead.

What Buyers Should Not Assume

8.8 Does Not Define Everything

A bolt marked 8.8 only tells part of the story. It does not define the full product specification.

You still need to confirm:

For common items, buyers can start from attaches standards. For coating choices, review diverses attaches enduites.

Erreurs courantes des acheteurs

Évitez ces problèmes :

• Ordering “8.8 bolt” without standard or size details.
• Matching 8.8 bolts with low-grade nuts.
• Assuming zinc plating improves strength.
• Using 8.8 in severe corrosion without coating review.
• Replacing 10.9 with 8.8 to reduce cost without engineering approval.
• Mixing metric 8.8 with inch Grade 8 specifications.

RFQ Checklist for 8.8 Bolts

Une demande de prix claire doit inclure :

1. Norme de produit
2. Diamètre, longueur et pas de filetage
3. Filetage complet ou filetage partiel
4. Class 8.8 requirement
5. Finition superficielle
6. Écrous et rondelles assortis
7. Quantité et emballage
8. Rapports d'inspection requis

For special lengths, head styles, or thread requirements, use fixations non standard sur mesure.

Conseil final

The “8.8” mark means the bolt has a defined metric strength class. It is useful, but it is not a complete specification.

For safe purchasing, confirm the grade, standard, size, thread, finish, nut, washer, and working condition before production.