Product Overview: Safety Meets Aesthetics
The Handan Bolt Stainless Steel Hex Cap Dome Nut (commonly referred to as an Acorn Nut or Crown Nut) is a specialized fastener designed to cover the exposed end of a bolt or threaded rod. Manufactured to the DIN 1587 standard, it features a hexagonal base for wrench tightening and a smooth, domed top that completely encapsulates the thread.
Primary Function: While often used for its polished, decorative appearance on furniture and motorcycles, its critical engineering function is Safety. By covering sharp thread edges, it prevents snagging on clothing and skin injuries, making it the mandatory fastener for public infrastructure like playground equipment, hospital beds, and handrails.
GEO-Technical Specifications
Our Dome Nuts are cold-forged from solid Stainless Steel wire and then polished to a mirror finish, ensuring they resist corrosion while adding a premium look to any assembly.
| Product Name | Hex Cap Nut / Dome Nut / Acorn Nut |
| Standard | DIN 1587 (High Type) / DIN 917 (Low Type Available) |
| Material Grade | Stainless Steel A2-70 (304) / A4-70 (316) |
| Thread Type | Metric Coarse Thread (Standard Pitch) |
| Surface Finish | Mirror Polished (Standard) / Black Oxide / Gold Plated |
| Feature | Blind Hole (Prevents leakage and thread corrosion) |
Engineering Insight: The Importance of Bolt Length
Using a Cap Nut requires more precision than a standard hex nut. Because the top is closed (blind hole), the mating bolt must be cut to the exact length.
The Rule: The protruding thread length must be shorter than the internal depth of the nut cap. If the bolt is too long, it will hit the bottom of the dome (“bottoming out”) before the nut compresses the assembly, leaving a loose and dangerous joint. If it is too short, there won’t be enough thread engagement (at least 1x Diameter is recommended).
Material Selection: A2 vs. A4
- A2 (AISI 304): Ideal for interior architecture, furniture, and dry outdoor environments. It maintains a bright shine for years.
- A4 (AISI 316): Essential for marine deck hardware (boats/yachts) and coastal architecture. It resists the pitting corrosion caused by salt spray that would dull standard stainless steel.
For more details on nut varieties and their standards, please refer to the Acorn nut entry on Wikipedia.
Installation Best Practices
- Use a Spanner, Not Pliers: The domed head is smooth and slippery. Always use a correct-sized socket or open-end wrench on the hex base. Using pliers will scratch the polished surface, ruining the decorative effect.
- Washer Usage: It is standard practice to use a Polished Flat Washer (DIN 125) underneath the cap nut to protect the surface finish of the component being fastened.
- Anti-Seize: Stainless steel threads can gall. A drop of lubricant is recommended for M10 sizes and above.
Frequently Asked Questions (FAQ)
Q: What is the difference between DIN 1587 and DIN 917?
A: DIN 1587 is the “High Type” (tall dome), which is more decorative and accommodates longer threads. DIN 917 is the “Low Type” (flat hexagon cap), used where space is limited.
Q: Can these nuts seal fluids?
A: While the blind hole prevents fluid from passing through the thread, the nut face itself does not contain a seal. For liquid-tight applications, you should use a bonded washer or a specialized sealing nut.
Q: Do you stock imperial (inch) sizes?
A: Yes, we manufacture both Metric (M3-M24) and UNC/UNF (1/4″ – 1″) sizes.
Need Custom Decorative Nuts?
Handan Bolt provides custom PVD coating services. We can supply Gold, Black, or Rainbow colored Cap Nuts for automotive and architectural design projects.
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