STAINLESS STEEL COUNTERSUNK HEAD SOLID RIVETS DIN 661

Countersunk Head Solid Rivets DIN 661 — DIN 661 uses the same solid-shank construction and two-sided setting process as the round head version, DIN 660, but the factory-formed head is shaped to sit flush with the surface rather than proud - for joints where a protruding head can't be tolerated, such as chute or hopper linings, moving machinery guards, or panels needing a smooth outer face. Because one head is pre-formed at manufacture, only the fixing hole beneath that head needs a matching countersink; the plain end of the shank still passes through both parts and is hammered or pressed over on the reverse side in the usual way to complete the joint, so access to both faces during installation is still required exactly as it is for the round head pattern. Getting a clean flush result depends on the countersink being cut to the correct angle and depth before the rivet is fitted - an incorrect countersink will leave the head slightly proud or seated unevenly even though the shank and reverse head form correctly. Typical uses mirror DIN 660's structural and fabrication applications, narrowed to jobs where the countersunk face specifically needs to be smooth: enclosure panels, ductwork, and machine guarding are common examples. Sizing follows the same logic as any solid rivet - shank diameter for the shear load expected, overall length to clear the combined material thickness with enough shank left to form a solid, well-filled second head on the plain end. On grade, A2 stainless covers most general engineering and construction use; A4 earns its premium in marine, coastal, or washdown environments where chloride exposure would otherwise accelerate pitting corrosion, and as with any rivet joining dissimilar metals, checking for galvanic corrosion risk between the rivet and parent material is worthwhile before specifying at volume.

FAQs
Does access to both sides of the joint still apply?
Yes - like all solid rivets, the tail end still needs to be accessible so it can be formed into a second head; only the pre-formed head is flush.

Can the countersunk head be reformed if the hole countersink is slightly wrong?
No - the head is pre-formed at manufacture to a fixed angle, so the fixing hole's countersink needs to match that angle; a mismatched countersink can't be corrected by adjusting the rivet during installation.

Are DIN 660 and DIN 661 interchangeable in the same drilled holes?
Only the shank and clearance hole are common - the countersunk version additionally needs the head-side hole countersunk to the correct angle, so a hole prepared for DIN 660 isn't automatically ready for DIN 661.