Product and application brief
Cap nuts have a hexagonal wrenching body and a closed end covering the projecting end of a mating threaded part. Rounded versions are also called dome or acorn nuts. A cap profile identifies a construction, not a universal performance rating. Specify the required form separately from thread, material and finish.
Product forms and reference names
| Product form / field | Reference and distinguishing details |
|---|---|
| High-type hexagon cap nut | DIN 1587:2021-11 identifies hexagon cap nuts, high type. Use the selected edition and size to establish the actual geometry; this reference does not assert FastenerBridge compliance. |
| Low-type hexagon cap nut | DIN 917:2021-11 identifies hexagon cap nuts, low type. A shorter exterior cap does not establish usable internal depth or interchangeability with a high type. |
| Drawing-based cap profiles | A drawing may define a different crown, overall height or body shape. A custom profile is not automatically a DIN variant. |
Closed end and internal clearance
Unlike a through nut, the capped cavity has an end. State the mating thread projection and the required usable internal depth so the selected geometry can be checked for fit. Exterior dome height alone is insufficient: threaded length, internal relief and closed-end thickness may differ. Do not assume that reaching the closed end means the assembly has seated correctly.
Thread and mating-part identification
Provide the thread system, nominal diameter and pitch or threads per inch. Where relevant, include the specified thread tolerance or fit, handedness and the mating-part drawing. Similar-looking metric and inch cap nuts are not interchangeable solely because their outside dimensions look alike.
Material, finish and functional requirements
Identify the requested material designation and coating or finish separately. A closed dome alone establishes neither a sealed joint nor a locking feature. If sealing, prevailing torque or other performance is required, provide the separate specification and evidence requirements; these are not implied by the illustration or category name.
Specification fields
| Product form / field | Reference and distinguishing details |
|---|---|
| Product identity | High type, low type or drawing reference; include the requested standard designation and edition if applicable. |
| Thread | System, diameter, pitch or TPI, and required tolerance/fit where specified. |
| External geometry | Across flats, overall height, cap profile and any drawing-controlled body dimensions. |
| Internal fit | Mating thread projection, usable internal depth and required threaded length; include any clearance or relief requirements. |
| Material and finish | Requested material designation, coating or finish and any separate inspection-document requirements. |
| Quantity and attachments | Quantity with unit, size-by-size list and drawing revision; mark dimensions or requirements still awaiting confirmation. |
Common product questions
Are cap nuts, dome nuts and acorn nuts the same?
The names commonly overlap for closed, rounded-end nuts. Confirm the actual profile, thread and drawing rather than relying on the name alone.
Can a high cap nut replace a low cap nut?
Not on appearance alone. Check the selected geometry, thread, available space and usable internal depth against the mating part.
Does a closed cap make the connection waterproof or self-locking?
No such performance is established by the closed shape alone. Sealing and locking requirements need their own specification and supporting evidence.
Related nut types
Product references
References checked 6 October 2026 explain product identity. Third-party model names and approvals are not FastenerBridge brand affiliation, stock or certification claims. Final geometry and requirements follow the selected specification.