Parting (or "cut-off") separates one piece into two — the tool feeds straight in until the bar is cut through. Grooving makes a slot or recess in the surface without cutting through — for O-rings, snap rings, oil seals, or reduced-diameter shoulders. Both use the same MGMN-style inserts and similar holders, so one tool kit covers both. The difference is depth of cut and feed strategy: parting goes all the way; grooving goes to a defined depth.

2 mm (MGMN200) is the safest default. It handles most parting jobs on 12–30 mm bar, cuts standard O-ring grooves, and is the most widely available width in the MGMN family. Step down to 1.5 mm only when you need to minimise material loss on small or expensive bar (brass, watchmaking). Step up to 3 mm when bars are 25 mm+ or when you need extra rigidity for deep grooves.

It decodes part by part: M = mono-block grooving holder; G = grooving / parting type; E = external; H = horizontal feed direction; R = right-hand cutting; 20 × 20 = shank cross-section in millimetres; -3 = insert seat width in millimetres. So MGEHR2020-3 is an external, right-hand grooving holder with a 20×20 mm square shank that takes a 3 mm-wide MGMN insert. Swap the R for an L and you get the left-hand version. Swap the E for an I and you get an internal (boring-bar) version.

Parting is the most chatter-prone operation on a lathe because the tool projects a long, thin blade into a deep narrow slot. The fixes, in order: (1) reduce the tool overhang — the blade should stick out only as far as the bar diameter requires, plus 1–2 mm; (2) raise the spindle speed if the workpiece is small, drop it if the workpiece is large; (3) increase feed rate to break the chip; (4) add a small chamfer to the leading edge of the insert; (5) use a stiffer holder — an Iscar self-grip blade is far more rigid than a thin MGEHR holder past 8 mm depth.

Yes — MGMN inserts are explicitly dual-purpose. The "M" in MGMN stands for "multi-functional grooving" and the geometry handles both parting (axial straight-in feed) and grooving (radial in-feed to defined depth). What matters is matching the width to the operation: if you want a 2 mm-wide groove, use a 2 mm insert; if you want to part a bar with the narrowest possible kerf, use the smallest width that's stiff enough for the bar diameter.

For carbon and alloy steel, PC9030 (PVD TiAlN coating) is the all-rounder — long edge life at moderate speeds. For stainless steel, Inconel or titanium, switch to a tougher PVD grade like Sandvik GC1125 or Iscar IC908 — they resist the heat and built-up edge that wreck steel-grade inserts. For cast iron, an uncoated K-grade or CVD-coated NC3030 cuts cleanest at high speed with no coolant. When in doubt, ask — we'll match the grade to the part drawing before you order.

Rule of thumb for an MGEHR2020 holder: cut depth up to about 22 mm is safe (roughly the height of the blade portion above the holder body). Beyond that, the blade flexes and chatter starts. For 22 mm to 35 mm depth, switch to an Iscar Self-Grip GHDR-style blade — the tall, thin geometry resists deflection up to ~32 mm. Past 35 mm, you're into specialty deep-grooving territory (GTN-4 / -5 / -6 with reinforced blade thickness).

You can run a standard MGMN insert on the face if the groove diameter is large and the blade clears the workpiece. But for true face grooving — especially small-radius circular grooves — use a dedicated face-grooving holder (MGFHR series) with a curved blade that follows the groove arc. The insert itself is a normal MGMN; only the holder geometry changes. Trying to face-groove with an OD holder usually fails by the blade rubbing the groove sidewall.

MGMN is the open standard — almost every manufacturer makes a compatible 2 mm or 3 mm MGMN insert, so they're cheap and universally available. GTN is Iscar's self-clamping system — the insert snaps into a rail-like seat with no clamp screw. GTN gives faster insert changes (no Torx key) and is rated for deeper, more rigid cuts — but the blades and inserts are Iscar-only. For most workshops, MGMN is the practical default; GTN is worth it on production cells where insert change time matters.

Most MGMN inserts are "double-ended" — one cutting edge at each end of the rectangular body. When the first edge dulls, you flip the insert and seat the fresh end. Effectively two inserts for the price of one. The exception is single-ended grooving inserts like Sandvik N123 / CoroCut 1-2, which sacrifice the second edge for a more aggressive chip-breaker geometry on the active edge — useful for stainless and superalloys where chip control matters more than edge count.

Technically yes, but you'll burn the insert in 30 seconds. Stainless work-hardens at the cutting edge and the chip carries away most of the heat — without coolant or air-blast, the insert tip glows orange and loses hardness almost immediately. Run flood coolant (preferred) or high-pressure air-blast through the cut. If your machine doesn't have through-tool coolant, set up an external nozzle aimed at the chip exit. Carbide grade also matters — PC9030 or GC1125 will tolerate intermittent dry cuts; cheap K-grade inserts will not.

Genuine. We're authorised distributors for Korloy and Pafana in the UAE, and stock Iscar and Sandvik Coromant lines through their regional channels. Every insert ships in original branded packaging with the lot code. We do also offer a few Korean-made compatible alternatives where the price difference matters and the application is non-critical — but only on request, never substituted silently.