MS F1 S 3815 Composite Hex Nuts

These fasteners consist of a hex nut permanently attached to a rectangular, perforated 38 × 15 mm base plate. They are designed to provide a permanently integrated internal thread in the component. This design is particularly suitable where there is insufficient space for a round base plate or where a narrow, elongated load introduction area is structurally advantageous. Typical applications include composite construction, vehicle and boat building, model making, mould making and equipment construction, for example for attaching panels, brackets, fittings, supports and installed components.

Rectangular 38 × 15 mm Base Plate

The narrow base plate provides broad load distribution while requiring only limited installation width. This is particularly advantageous on narrow component areas, ribs, webs, profiles or other locations with restricted installation space. The perforations in the base plate allow resin or adhesive to pass through during laminating or bonding. In addition to the adhesive bond, this provides mechanical interlocking within the laminate or adhesive structure. The actual load-bearing capacity is not determined by the thread size alone, but depends significantly on the laminate structure, bonding area, resin or adhesive system and the type of applied load.

Version with Through Thread

The designation S identifies the open or “sighted” version with a central through-opening in the base plate. The internal thread is therefore open at the underside. Provided that the component is designed accordingly, a screw can extend beyond the nut and through the plane of the base plate. The design must therefore provide sufficient clearance or a corresponding hole or recess behind the fastener.

Processing

Laminating in / embedding
The fastener can be integrated directly into the laminate structure during manufacture of the component. Resin and reinforcement layers should engage the base plate as uniformly as possible. The perforated base plate promotes mechanical interlocking with the laminate. For more highly loaded joints, it should be adequately integrated into the laminate structure and not merely covered by a thin outer layer.

Subsequent bonding
Alternatively, the fastener can be bonded to an already finished component. A structural adhesive suitable for the respective substrate should be used. The bonding surfaces must be clean, dry and free from dust, grease, release agents and other contaminants that could impair adhesion. Smooth surfaces should be prepared in accordance with the processing instructions of the adhesive system used. For uneven surfaces or larger bond gaps, a sufficiently thixotropic, gap-filling structural adhesive is recommended.

Suitable Materials

Depending on the manufacturing and fastening method, suitable substrates include:

• GRP laminates
• CFRP laminates
• SMC and BMC components
• thermoset and thermoplastic materials
• sandwich components
• polymer foams
• elastomers and rubber
• other sufficiently load-bearing moulded parts and materials

Dimensions and Versions

The base plate of this series has a standard size of 38 × 15 mm. The individual versions differ in the size of the internal thread. R&G offers versions with different metric internal thread sizes.

Material

Manufactured from zinc-plated mild steel.

Version Designation

Example: MS F1 S 3815 M6

• MS = mild steel
• F1 = hex nut with internal thread
• S = open version with through-opening in the base plate
• 3815 = rectangular base plate 38 × 15 mm
• M... = metric internal thread size

Technical Notes

• The permissible load is not determined by the thread size alone. Important factors include the laminate structure, bonding area, resin or adhesive system and the quality of load transfer into the component.
• The rectangular base plate is particularly suitable for installation situations with limited width. For highly loaded joints, the load direction and orientation of the base plate should be taken into account in the design.
• For high tensile and shear loads, the base plate must be adequately integrated into the laminate or bonded joint.
• With sandwich components, care must be taken to ensure that the skins and core material are not locally overloaded by the applied forces.
• The through-opening of the S version must be taken into account in the component design, particularly if the screw extends beyond the hex nut.
• For CFRP components exposed to moisture, the electrochemical compatibility between the carbon fibres and the metallic fastener must be considered. Electrical or galvanic isolation may be required depending on the application.
• For safety-relevant or highly loaded joints, we recommend testing the complete connection on the intended component under realistic service conditions.