GlossaryKind of term: Manufacturing termGroove
What is a groove?
A groove is a narrow cut, usually running round a shaft, inside a bore or in an end face, for example for an O-ring, a retaining ring or a run-out.
In an end face the groove is cut axially and forms a ring around the centre line. Well-known examples are the O-ring groove, sized from the seal supplier's table or ISO 3601-2, and the retaining ring groove, sized from DIN 471 on a shaft and DIN 472 in a bore. The drawing gives the width, the groove bottom diameter and often radii in the corners. An O-ring groove usually also carries a roughness requirement on flanks and bottom, because that is where the ring seals. On a prismatic part a groove can also run straight or along a free contour.
What does a groove depend on?
For an O-ring groove the depth follows from the ring's cross-section and the intended squeeze, which lies within a range that depends on static or dynamic sealing, radial or axial installation and the ring material. An external groove is cut with a grooving tool, an internal groove with a grooving tool on a boring bar, with less stiffness and harder chip evacuation, and an axial groove with a holder curved for that diameter range. When the groove is wider than the insert, you plunge several times or turn the bottom flat lengthwise.
How does a groove work in practice?
A groove is often a short operation, but a tight width, a fine roughness on the flanks or corner radii can call for a second pass or a dedicated form insert. An internal groove in a small, deep bore often needs lower cutting data, and the cut is out of sight. It is measured with a groove micrometer, an internal gauge or a CMM, depending on access and tolerance. Whether several grooves can share one tool depends on width, form and corner radius.
What is a groove often confused with?
A groove is not a slot: a slot is an elongated recess with two parallel walls in a prismatic part, while a groove usually runs round. And not every groove is a relief: a thread relief is the groove at the end of a thread or at a shoulder, so the tool can run out and a mating part can seat flat.
Frequently asked questions
How deep should an O-ring groove be?
That follows from the ring's cross-section and the squeeze that suits static or dynamic, radial or axial sealing. If the drawing only gives the ring size, use the seal supplier's table or ISO 3601-2, and when in doubt ask which seal is meant.
Is an internal groove more expensive than an external one?
Often, yes. An internal groove needs a grooving tool on a boring bar, you cannot watch the cut, and the chips have to leave the bore. In a small bore with a deep groove, feed and speed come down.