Our metric nuts cover the complete fastening range: standard hex nuts, nyloc self-locking nuts, flange nuts, castle and slotted nuts, dome and wing nuts. Manufactured to DIN and ISO standards in a wide choice of materials and strength grades, our nuts pair with bolts and studs to form reliable, serviceable threaded joints.

Nuts - Metric Sizes

What Is a Nut?

A nut is an internally threaded fastener that mates with a bolt, screw, or stud to clamp components together. As the nut is tightened, its thread converts rotation into linear clamping force, holding the joint under tension. Nuts are among the most fundamental engineering components, and the many variants  locking, flanged, castellated, decorative, and hand-operated  each solve a specific fastening problem while sharing the same core threaded principle.

At Metric Specialties we stock the full metric nut family: hex nuts (DIN 934 / ISO 4032) for general use, thin lock nuts (DIN 439) as jam nuts, nyloc nuts (DIN 985) with a nylon insert that resists vibration loosening, flange nuts (DIN 6923) with a built-in washer face, castle and slotted nuts (DIN 935 / 937) for split-pin locking, dome (cap) nuts for a finished appearance and thread protection, and wing nuts for tool-free hand adjustment. Every type is available across multiple strength grades and corrosion-resistant materials.

Key Features and Benefits

• Complete Locking Range: Nyloc, flange, castle, and jam nuts provide vibration resistance for every application.
• Matched Strength Grades: Nut property classes are matched to bolt grades to develop the full strength of the joint.
• Serviceable Joints: Nuts allow assemblies to be tightened, adjusted, and dismantled repeatedly.
• Finished and Functional Styles: Dome nuts protect threads and add a clean finish; wing nuts allow tool-free adjustment.
• Corrosion Options: Zinc-plated and A2/A4 stainless grades suit indoor to marine environments.

Materials and Finishes

• Carbon Steel Class 8 (Zinc Plated): Standard general-purpose nut grade for most engineering.
• Carbon Steel Class 10: Higher-strength nuts matched to Class 10.9 bolts.
• Stainless Steel A2 / A4: Corrosion-resistant grades for outdoor, marine, and hygienic use.

Standards Compliance

• DIN 934 / ISO 4032  Hexagon full nuts.
• DIN 985 / ISO 10511  Nylon insert self-locking nuts.
• DIN 6923  Hexagon flange nuts.
• DIN 935 / 937  Castle and slotted nuts.

Common Applications and Industries

Nuts appear in every bolted assembly across construction, automotive, machinery, and general manufacturing. Standard hex nuts serve general fastening, while nyloc nuts lock automotive, agricultural, and vibrating machinery joints without additional hardware. Flange nuts speed assembly and spread load on thin panels and brackets, and castle nuts secure axles, steering, and wheel bearings where a positive split-pin lock is mandatory for safety.

Dome (cap) nuts protect exposed thread ends and give a clean, finished appearance on furniture, railings, and visible assemblies, while wing nuts allow tool-free adjustment on guards, covers, and equipment that is frequently opened. The breadth of nut types means there is a correct solution for locking, appearance, adjustment, or load distribution in almost any application.

How to Choose the Right Nut

First match the thread size and pitch to the bolt or stud, then select the strength grade so the nut is at least as strong as the fastener it pairs with. Next decide whether locking is required: nyloc and flange-serrated nuts resist vibration for general joints, while castle and slotted nuts provide a positive mechanical lock for safety-critical axle and steering applications.

Consider function and appearance: dome nuts finish and protect exposed threads, wing nuts allow hand adjustment, and thin jam nuts lock a position on threaded rod. Finally choose the material and finish for the environment, from zinc-plated steel indoors to A2 or A4 stainless for marine, outdoor, and hygienic use.

Size Range and Availability

Available in M2 through M64 across hex, nyloc, flange, castle, dome, and wing nut types, in zinc-plated steel Class 8/10 and A2/A4 stainless.

Why Buy From Metric Specialties

As dedicated metric fastener specialists, we hold nuts in the sizes, grades, and finishes that engineers actually need, backed by clear DIN and ISO standard references so you can specify with confidence. Every item is sourced to recognised standards and quality-controlled, giving you consistent thread fit, strength, and corrosion performance across repeat orders.

Whether you need a single item for a repair or bulk quantities for production, our range, technical guidance, and fast dispatch help you find the exact fastener for the job. If you are unsure which size, grade, or finish suits your application, our team can help you match the right product to your load, environment, and standard, so your assemblies are reliable and built to last.

Frequently Asked Questions (FAQs)

1. What types of nuts do you stock?

We stock hex nuts, thin jam (lock) nuts, nyloc self-locking nuts, flange nuts, castle and slotted nuts, dome (cap) nuts, and wing nuts, across a full range of materials and strength grades.

2. What is a nyloc nut and how does it work?

A nyloc nut has a nylon collar that the bolt thread cuts into as it is tightened, creating friction that resists loosening from vibration. It is one of the most common self-locking nuts.

3. What is the difference between a hex nut and a flange nut?

A flange nut has an integrated washer-face flange that spreads clamp load and can include serrations for grip, while a standard hex nut has a plain bearing face and often needs a separate washer.

4. How do I match a nut's strength to a bolt?

Nut property classes (for example Class 8 or 10) are chosen so the nut is at least as strong as the bolt it pairs with. Using a correctly matched class ensures the joint develops full bolt strength.

5. What is a castle nut used for?

A castle (slotted) nut has slots in its crown for a split pin that passes through a cross-drilled bolt, locking the nut mechanically. It is used on axles, steering, and safety-critical joints.

6. What is a dome nut?

A dome or cap nut has a closed, rounded top that covers and protects the bolt thread while providing a clean, finished appearance. It is common on visible or contact-sensitive assemblies.

7. Are your nuts available in stainless steel?

Yes. We stock A2 and A4 stainless nuts across most types for corrosion-resistant use in marine, outdoor, food, and chemical environments.

8. Can nyloc nuts be reused?

Nyloc nuts can be reused a limited number of times, but the nylon insert wears with each use and loses locking effectiveness. For safety-critical joints, fitting a new nyloc nut is recommended.

9. What is a jam nut or lock nut?

A jam nut is a thin nut tightened against a standard nut to lock it in place, preventing loosening. It is also used to set position on threaded rod and adjustable linkages.

10. What sizes do you stock for nuts?

We stock M2 through M64 across hex, nyloc, flange, castle, dome, and wing nut types, in zinc-plated steel Class 8/10 and A2/A4 stainless.