What is in this group
| Family | Covers | Reach for it when |
|---|---|---|
| Turning inserts | CNMG, DNMG, WNMG, VNMG, TNMG, grooving and threading inserts, plus positive CCMT and DCMT | A diameter or face is being turned and the edge should be indexable |
| Taps and thread mills | Spiral flute, spiral point, forming taps and thread mills | A thread has to be produced, cut or formed |
| Boring systems | Damped anti-vibration bars, indexable boring bars, fine boring heads | An internal diameter must be produced or corrected beyond about 3xD |
| Turning tool holders | External and internal holders, grooving and threading holders, VDI | An insert needs locating in a turret or tool post |
Material group comes first
Every turning decision starts with the ISO material group, because that sets the coating direction and the failure mode the tool has to survive.
Within a group the trade is wear resistance against edge toughness: a harder grade lasts longer in a continuous cut, and a tougher grade survives an interrupted one. Getting that wrong produces a tool that fails for a reason no parameter change will fix.
- P for steel, with CVD-coated grades for continuous turning
- M for stainless, with sharp PVD-coated grades that cut rather than rub
- K for cast iron, where a tough edge handles the as-cast skin
- N for aluminium, where a polished uncoated edge prevents built-up edge
- S for titanium and nickel alloys, with hot hardness and through-coolant
- H for hardened steel, where ceramic or CBN takes over from carbide
The overhang problem in boring
A boring bar is a cantilever, so its stiffness falls with the cube of the overhang. A steel bar is comfortable to about three times diameter, heavy metal and carbide extend that to five or six, and beyond that the bar has to be tuned-mass damped rather than simply made stiffer.
That is why boring is quoted by bore diameter and depth together rather than by diameter alone. The same bore at twice the depth is a different tool.
In this group
5 page(s)
Turning Inserts
Precimill supplies indexable turning inserts in the standard ISO shapes: CNMG and SNMG for general turning, DNMG and VNMG for profiling and finishing, WNMG for roughing...
Read moreTaps and Thread Mills
Precimill manufactures cutting taps, forming taps and thread mills for metric, UNC, UNF, BSP and NPT threads. Spiral flute taps pull chips back out of blind holes, spiral...
Read moreBoring Systems and Anti-Vibration Boring Bars
Precimill manufactures boring systems for deep and precision bores: tuned-mass damped anti-vibration bars that suppress chatter beyond four times diameter, indexable...
Read moreTurning Tool Holders
Precimill manufactures external and internal turning tool holders for the standard insert shapes, plus grooving and threading holders. Shanks are hardened and ground to...
Read moreCCMT and DCMT Positive Rake Turning Inserts
CCMT, DCMT and VCMT are positive rake inserts: they cut with a sharp, free-cutting edge and generate significantly lower cutting force than a negative insert of the same...
Read moreFrequently asked questions
Which insert shape should I start with?
CNMG for general turning and roughing, because it is strong and widely available. Move to DNMG or VNMG when profiling or finishing matters, to WNMG for heavy roughing with six usable edges, and to CCMT or DCMT positive geometries when the machine or the part is not rigid enough for a negative insert.
When do I need a damped boring bar?
Beyond roughly five times diameter. A steel bar is comfortable to about 3xD, heavy metal and carbide extend that to 5 or 6xD, and past that chatter becomes the limiting factor rather than the cutting edge.
Should I tap or thread mill?
Tap for high-volume small threads in free-cutting material, where cycle time dominates. Thread mill for large threads, hard or gummy materials, blind holes needing full depth, and expensive parts where a broken tap would scrap the component.
Do you supply the holder with the insert?
Yes, and it is the safer way to buy. Insert pocket wear in the holder causes size drift and unexplained insert breakage, so supplying the two together lets us verify the tip height and position as a set rather than assuming each is separately in tolerance.
What decides between turning and boring for an internal feature?
Boring is a corrective operation: it brings a drilled or cast hole to size and position. Where the hole is already close and the tolerance is loose, drilling or reaming is faster. Where the tolerance is tight or the bore must be exactly on centre, boring is the operation that achieves it.