What are M24 Screws?

M24 screws are large-diameter metric fasteners with a 24mm thread, available in both coarse (3mm) and fine (1.5mm) thread pitches. Firmly in the heavy-duty category, the M24 bolt is a standard specification in structural engineering, heavy plant and large-scale infrastructure projects.

In bridge construction, M24 bolts are used to connect steel girders and cross-bracing members, where every joint must sustain enormous dead and live loads over decades of service. Whether specified as an M24 cap head screw for precision-machined assemblies or an M24 bolt in a structural connection, this fastener size delivers the mechanical performance that critical infrastructure demands.

How M24 Size Screws Work

M24 screws are engineered for applications where joint failure is not an option. Their 24mm diameter provides a large tensile stress area, enabling high preload values that clamp thick steel components together with authority.

In tower crane slewing rings, M24 bolts resist the combined tensile and shear forces generated during rotation under load. In rail infrastructure, M24 cap head screws secure track base plates to concrete sleepers, enduring millions of dynamic load cycles from passing rolling stock. The coarse (3mm) pitch allows for efficient installation, offering faster threading speed, while the fine (1.5mm) pitch is preferred where tighter preload control and enhanced resistance to self-loosening are required.

Materials M24 Screws Are Made From

Our M24 screws are crafted from high-quality materials to support a variety of operational requirements:

• High-Tensile Steel: Provides exceptional strength and durability, the industry standard for structural bolting and high-load applications.
• Stainless Steel Grades A2 and A4: A2 is a versatile option for general use, while A4 offers superior resistance to corrosion, perfect for marine and chemical environments.
• A4-80 Stainless Steel: Combines the corrosion resistance of A4 with enhanced tensile strength for demanding installations.
• BUMAX Stainless Steel: High-strength stainless steel fasteners offering mechanical performance comparable to high-tensile steel with full corrosion resistance.
• Brass: Offers excellent resistance to corrosion and is easy to machine, making it suitable for decorative and electrical applications.
• Aluminium: Lightweight with good corrosion resistance, suited to applications where weight reduction is a priority.
• Nylon and PEEK: Lightweight thermoplastics offering excellent chemical resistance and high thermal stability, used in specialist engineering projects.

Sizes and Types of M24 Screws Available

M24 screws come in a wide range of configurations to meet various project specifications:

• Lengths: Available in lengths ranging from 25mm to 300mm.
• Head Types: Cap head, countersunk and hexagon profiles are available to suit different installation and clearance requirements.
• Thread Types: Fully threaded, partially threaded and specialised options like captive screws provide flexibility for different fastening requirements.
• Drive Types: Choose from Hex Socket and External Hex drive styles to suit your tooling preferences.
• Finishes: Options such as AccuLock thread locking prevent loosening under vibration, while AccuBlack chemical blackening delivers a sleek, dark aesthetic.

FAQs

Q: What is the thread pitch of an M24 screw?

 A: M24 screws are available in coarse (3mm) and fine (1.5mm) thread pitches. The coarse pitch represents a step up from the 2.5mm pitch used on M18, M20 and M22 fasteners, reflecting the larger diameter and the need for proportionally deeper thread engagement. The fine pitch offers greater tensile strength and vibration resistance.

Q: What hex key fits an M24 cap screw? 

A: An M24 socket cap head screw (DIN 912) requires a 19mm hex key for installation and removal.

Q: Are M24 bolts used in structural steelwork?

 A: Yes. M24 bolts in high-tensile steel grades 8.8 and 10.9 are one of the standard sizes specified for structural connections in accordance with BS EN 15048 (non-preloaded) and BS EN 14399 (preloaded assemblies).

Q: What is the across-flats dimension of an M24 hex bolt?

 A: An M24 hexagon bolt has a standard across-flats dimension of 36mm, requiring a 36mm spanner or socket.

Q: Can I get M24 screws with pre-applied thread lock?

 A: Yes. AccuLock thread-locking patches are available as a pre-applied finish on M24 screws, eliminating the need for liquid threadlocker during assembly and providing reliable resistance to vibration-induced loosening.

Bespoke M24 Screws Manufacture.

High precision, bespoke manufacture of M24 Screws to customer specification. State of the art facilities specialising in both small batch prototyping and large scale manufacture.