DIN 547 Round Nuts with Drilled Holes in One Face

This product is a round nut manufactured to DIN 547 , characterised by a cylindrical outer profile with a series of drilled holes on one face. Designed for use with shaft ends or threaded spindles, these nuts are typically secured using a tab washer (DIN 540) or a cotter pin passed through the drilled holes to prevent loosening under vibration or dynamic loads. Available in carbon steel with various surface finishes or stainless steel grades, DIN 547 nuts provide a low-profile locking solution for mechanical assemblies, transmission components, and industrial machinery.

What are the dimensional specifications and hole configuration for DIN 547 round nuts?

The nut is defined by its nominal thread diameter d ranging from M4 to M48, with thread conformity to ISO metric coarse pitch (6H) . The outer diameter (D) and height (H) are standardised per DIN 547, with the cylindrical outer surface providing a smooth profile suitable for limited clearance applications. The drilled holes—typically 4 holes for smaller diameters and 6 or more holes for larger sizes—are evenly spaced around the circumference on the upper face. Hole diameters and pitch circle dimensions are specified to accommodate standard cotter pins or locking wire, with hole positioning allowing 30° or 45° indexing to achieve precise alignment with shaft keyways or washer tabs.

What material property classes and surface finishes are available for DIN 547 nuts?

For carbon steel versions, property classes 5, 6, or 8 to DIN EN ISO 898‑2 are available, with class 8 nuts offering a proof load stress of 800 MPa for compatibility with property class 8.8 bolts and threaded shafts. Stainless steel options conform to A2‑70 (304 series) or A4‑70 (316 series) per ISO 3506, providing corrosion resistance for outdoor, marine, or chemically exposed environments. Surface treatments for carbon steel include electro‑zinc plating (5–12 μm) for basic corrosion protection, hot‑dip galvanizing (40–80 μm) for enhanced durability, or black oxide for cosmetic finish with minimal dimensional change.

How does the drilled-hole design interface with locking components for secure fastening?

The drilled holes are specifically positioned to align with the external teeth of a DIN 540 tab washer or to accept a cotter pin (ISO 1234) after the nut is torqued to the specified preload. When used with a tab washer, the washer’s external tab is bent into one of the nut’s drilled holes after tightening, providing positive mechanical locking that prevents rotation regardless of vibration or thermal cycling. For applications requiring periodic disassembly, a cotter pin inserted through a drilled hole and a corresponding hole in the threaded shaft offers a reusable locking method. The number of holes (4, 6, or 8) enables fine adjustment of the tightening angle, typically in 30° increments, ensuring that the locking position can be achieved without over‑torquing or under‑torquing the assembly.