Parting line projection is a continuous ridge of material on the parting line along the ID or the OD of the ring, often caused by mold wear creating enlarged radii from the mold cavity to the flat plane of the tool. Excessive flash is a thin, film-like layer of material extending from the parting line projection.

Specification Max Allowable
Partine Line Projection Width (A)
(inches)**
Max Allowable
Partine Line Projection Length (B)
(inches)**
Max Allowable
Flash Length (C)
(inches)**
AS708* .003 .003 0 (all flash must be removed)
ISO 3601-3 CS .0039 .0028 0 (all flash must be removed)
AS871 .005 .003 0 (all flash must be removed)
ISO 3601-3 S,
DIN 3771 S
.0039 .0039 .0020
ISO 3601-3 N,
DIN 3771 N
.0039 .0039 .0028
MIL-STD-413C .003 Combined height of projection and flash must remain < .003
RMA OR-1 A .003 Combined height of projection and flash must remain < .003
RMA OR-1 B .003 Combined height of projection and flash must remain < .003
Note: No tool marks or defects discernible to the naked eye are permitted.
**The data above shows maximum allowable width, height and flash length of defect assuming an o-ring cross sectional diameter is between 0 and .1 inches.

Parting Line Projection and Excessive Flash diagram

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