Deep grooves cut into a face or shoulder are where turning tools fail first. We design the grooving tool around your groove radius, control chip evacuation, and hold the groove wall position through heat-treated stainless.
Most of these show up on the first article, not on the tenth. Catching them early is cheaper than re-cutting a hardened part.
A groove 175 mm deep with only 80 mm of open space has nowhere for chips to go. They curl back against the tool shank, raise cutting force, and stall the feed. The usual result is a broken insert and a scrapped part, or a groove wall pushed off position.
A standard grooving holder is wider than the groove arc at the back of the insert. On a grooved face with a radius profile, the shank contacts the wall behind the cutting edge, leaving a burnished band and pulling the tool off center. Groove width then drifts past tolerance.
Stainless with high plasticity work hardens the moment the tool rubs instead of cuts. Feed too light, and the next pass cuts through a layer that is harder than the base metal. Tool wear accelerates, and surface finish lands at Ra 3.2 μm instead of the Ra 0.4 μm the drawing calls for.
Sticky stainless and high cutting temperature form a built-up edge on the insert tip. It breaks off in cycles, leaving a torn groove floor and a Ra value that fails inspection. On a sealed face this becomes a leak path, not a cosmetic defect.
Two things decide whether a flat deep groove comes out right: the shape of the tool behind the cutting edge, and the order in which you remove material.
On a face groove, one corner of the tool cuts the groove floor and the wall, much like a boring bar. The back of that corner has to clear the arc of the groove. We grind the rear of the insert and the top of the shank to match the groove radius, then hold a relief angle so the shank never touches the wall. That single change removes the burnishing band and the centering error that comes with it.
The second corner is dressed for the opposite wall so the same tool can cut both sides of the groove without a second setup. Width is set by the tool, not by two separate passes, which keeps the groove within ±0.02 mm across the batch.
Rough turning comes first, then quench and temper to 269–292 HB, then the groove. Cutting a hardened groove in one pass is not realistic. We open the groove undersize with a narrow tool, widen it in steps, and step down the depth so each pass produces a chip short enough to clear the opening. High-pressure coolant aimed at the cutting edge breaks the chip and flushes it out.
Feed per revolution matters more than speed here. Too light a feed rubs the stainless and work hardens it. We set a feed high enough that the edge bites under the hardened layer rather than skating over it, and we keep the depth of cut constant so the insert wears evenly. Then the finishing pass cuts the groove wall and floor to Ra 0.4 μm where the drawing requires it.
Depth-to-width ratio is the deciding number. Below 4:1, a standard grooving holder works. Above that, the tool has to be purpose-built.
| Groove condition | Turning approach | What to watch |
|---|---|---|
| Depth-to-width under 4:1 | Standard grooving insert | Chip curling at the floor |
| Depth-to-width 4:1 to 8:1 | Narrow insert, stepped depth | Shank clearance and coolant reach |
| Hardened stainless above 269 HB | Rough, heat treat, then groove | Work hardening from light feed |
| Groove floor Ra 0.4 μm | Separate finishing pass | Built-up edge on the floor |
| Groove wall position ±0.02 mm | Single tool cuts both walls | Thermal growth across the batch |
| Blind groove with a corner radius | Tool rear ground to the radius | Shank rubbing the radius wall |
Grooves rarely come alone. Most parts that need a flat deep groove also need a bore, a cone face, or a milled feature in the same setup.
Grooves, bores, cones and faces on one lathe. Mill-turn centers cut the groove and the cross feature without a second fixture.
For grooved housings with angled ports or contoured faces that cannot be reached on a two-axis lathe.
Indexed work on cylindrical parts where grooves sit at more than one angular position.
Flat plates and manifolds with open grooves, where a milling cutter reaches better than a turning tool.
One-off grooved parts for fit checks before you commit to a production tool.
Bead blasting, polishing and passivation after grooving, without rounding the groove edges.
| Item | Range | Note |
|---|---|---|
| Maximum part size | 4,000 mm | Larger travel on 4,000 × 400 × 150 mm machines |
| Turning envelope | Ø400 mm rotary table | Mill-turn for grooved cylindrical parts |
| Tolerance | ±0.005 mm | Held on groove wall and floor position |
| Fine finish | Ra 0.2–0.8 μm | Finishing pass after the groove is opened |
| Materials | Stainless, alloy steel, aluminium, titanium | 303, 304, 316, 17-4PH, 4140, 6061, TC4 |
| Batch size | 1 to 10,000+ | No minimum order quantity |
| Inspection | 100% before shipment | Reports on request |
Wall and floor position held across the batch, not just on the first article. Verified on the CMM before shipment.
Groove floors and cone faces finished to Ra 0.2–0.8 μm where the drawing calls for a sealing surface.
Narrow openings with limited chip room are handled with stepped depth and high-pressure coolant.
Quenched and tempered 2Cr13 and similar grades turned after heat treat, not before.
We return a quotation and a free manufacturability review of your groove detail within 12 hours.
Once the drawing and material are confirmed, production can start within 24 hours.
Grooves act as seal seats and flow channels. The floor finish controls whether the seal holds.
Heat-treated steel grooves with batch-to-batch consistency and traceable inspection records.
Thin walls around a deep groove, where cutting force has to stay low to avoid distortion.
Stainless groove faces that need to be clean and burr-free after the finishing pass.
We turn grooves with a depth-to-width ratio up to about 8:1 when the opening is wide enough for chips to leave. Past that ratio, chip evacuation becomes the limit rather than the tool.
For very narrow, very deep grooves, send the drawing. We will tell you whether turning is realistic or whether the feature should be redesigned as a two-part assembly.
Rough the groove before heat treatment, leave stock on the walls and floor, then quench and temper, then finish the groove. Heat treatment moves the part, and a groove cut to final size before that will not stay in tolerance.
If the part is hardened above roughly 45 HRC, we normally grind or EDM the groove instead of turning it.
304 work hardens under the cutting edge. If the feed is too light, the tool rubs and the next pass cuts a harder layer, which raises tool wear and tears the groove floor.
We run a higher feed per revolution on stainless and keep the depth of cut constant. That puts the edge under the hardened layer instead of on top of it.
The rear of the grooving tool is ground to match the groove radius, with a relief angle behind the cutting corner. That is the difference between a clean wall and a burnished band.
It matters most on curved groove profiles, where a standard holder is wider than the groove at the back of the insert.
Ra 0.2–0.8 μm on a finishing pass, with a separate pass after the groove has been opened to size. A groove floor that seals needs this; a groove that only locates a part usually does not.
Tell us which groove faces are functional. Finishing every surface increases cycle time and cost for no benefit.
Yes. Groove wall and floor position are measured on the CMM against the datum called out on the drawing, and we inspect 100% of parts before shipment.
Inspection reports are available on request. If you need a first article report with the groove dimensions called out separately, ask for it at quoting.
There is no minimum order quantity. We run one prototype or a 10,000+ part production batch on the same process.
For prototypes we may cut the groove on a mill-turn center to skip a dedicated tool, which keeps the first article cheaper.
Yes. Uploads are treated as confidential, and we sign an NDA on request before any drawing is reviewed.
Your groove geometry and tool design stay with the job. We do not reuse a customer's special tooling on other work.
Upload the drawing with the groove section called out. You get a quotation and a manufacturability review within 12 hours, including whether the groove should be turned, milled, or redesigned.
12-hour quote100% inspectionNo minimum order
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