Round-Cord Rings

While O-rings are custom-made serial moulded products, round-cord rings are cut from an extruded cord. Round-cord rings are often used in cases where no suitable O-rings are available and as only a small number of pieces are needed, it would not be cost efficient to have them manufactured separately.

The improved physical quality of the butt-joint connection, which complies with DIN 7715, is one reason this type of connection has become widely used. As the mechanical characteristics of the vulcanized connection are lower than those of the extruded cord, we do not recommend the use of round-cord rings for dynamic seals, vacuums and gases. The cord diameter and perimeter tolerance according to DIN 7715 Part 3 and Class E2, respectively, is ± 0.8 per cent. O-ring tolerances are not applicable.

Profile dimension tolerances	DIN 7715 Part 3 E2
(cord diameter)	Tolerance ±
Up to 2.50 mm	±0.35 mm
2.50- 4.00 mm	±0.40 mm
4.00- 6.30 mm	±0.50 mm
6.30-10.00 mm	±0.70 mm
10.00-16.00 mm	±0.80 mm
16.00-25.00 mm	±1.00 mm

We manufacture round-cord rings from all major materials including NBR, EPDM, silicone and Viton.