A CNC cell rarely stops because a machine fails. It stops because the insert box is empty, or because the inserts that arrived look right but chip after a few parts. Cutting tools and abrasives are bought constantly, in small quantities, and often by description: “CNMG insert for steel”, “flap disc 120”. That works until a supplier sends a different grade, a different chipbreaker or a wheel rated for a slower spindle.
This guide covers how to specify cutting tools and abrasives so that any supplier quotes the same item, how to decide whether a substitute is acceptable, and what to check when abrasives arrive. Where to put these lines in a factory-wide purchasing plan is covered in MRO supply for factories in Vietnam.
💬 Have a list of inserts, drills or abrasives with maker codes? Send it to us with the material you cut, and we will check each line before quoting. Send your tool list.
Specify inserts by the full designation plus the maker’s grade
An indexable insert is fully specified only by three things together: the ISO shape-and-size code, the maker’s chipbreaker suffix and the maker’s grade. The ISO code alone fixes the geometry, not how the insert cuts.
The designation of indexable inserts is standardised in ISO 1832:2017, Indexable inserts for cutting tools — Designation. It gives a coding system so that common inserts can be ordered and specified in the same way across makers. Take a widely used turning insert, CNMG 120408, as makers list it:
| Part of the code | Example | What it tells you |
|---|---|---|
| Shape | C | 80° rhombic insert |
| Clearance angle | N | Negative insert (no relief angle) |
| Tolerance class | M | How tightly the insert’s dimensions are held |
| Hole and chip form | G | Fixing hole and chipbreaker type |
| Size | 12 | Cutting edge length class (inscribed circle 12.7 mm for this shape) |
| Thickness | 04 | 4.76 mm |
| Corner radius | 08 | 0.8 mm |
| Maker’s chipbreaker suffix | e.g. MR, MV, SM, TM | Geometry family; differs by maker |
| Maker’s grade | Maker’s own name | Substrate and coating; differs by maker |
The first part is shared by every maker who follows ISO 1832. The last two are not. Two inserts that are both “CNMG 120408” will fit the same holder, but may cut very differently because the chipbreaker and the grade are each maker’s own design.
So the item list for an insert line should hold:
- the full ISO designation;
- the maker and its chipbreaker suffix;
- the maker’s grade;
- the workpiece material and the operation (finishing, medium, roughing).
The last field matters when the preferred insert is unavailable, because it lets a supplier propose a comparable grade.
Drills, end mills and taps
Solid round tools do not share a single designation system like inserts. They are specified by the maker’s catalogue number, with diameter, length, flute count, shank type, coating and, for taps, thread standard and tolerance class. The catalogue number is what to put on the item list. A description such as “HSS drill 8.5 mm” will be quoted with whatever is cheapest.
Grades and the ISO application groups
Makers classify inserts by the ISO application groups P, M, K, N, S and H, which tell you what workpiece material a grade is meant for. Matching the group is the first step in finding a substitute grade, not the last.
ISO 513:2012, Classification and application of hard cutting materials for metal removal with defined cutting edges, classifies hardmetals, ceramics, diamond and boron nitride by application. Makers use its letter groups across their catalogues. As one maker describes them:
| Group | Workpiece material |
|---|---|
| P | Steel, from unalloyed to high-alloy, including steel castings |
| M | Stainless steel (Sandvik Coromant places ferritic and martensitic stainless under P; check how your maker groups them) |
| K | Cast iron |
| N | Non-ferrous metals such as aluminium, copper and brass |
| S | Heat-resistant super-alloys and titanium |
| H | Hardened steel and chilled cast iron |
Within each group, makers place grades along a scale from wear-resistant to tough. Two grades in the same group from different makers are not identical. A substitute grade is a starting point for a trial cut, not a guaranteed equivalent.
Makers whose inserts and round tools buyers commonly specify by part number include Sandvik Coromant, Mitsubishi Materials, Kyocera, Sumitomo Electric, Tungaloy, Kennametal and Iscar for inserts, and OSG and NACHI among others for drills and taps. These names are examples of brands buyers specify by part number. Naming them does not imply any relationship with, or authorisation from, these makers.
When a substitute is acceptable
Accept a substitute insert or tool only when the ISO geometry matches exactly, the application group and operation match, and the engineer who owns the process has approved a trial on your own part.
Substitution is common for three reasons: the preferred tool is out of stock, it has been discontinued, or another maker’s tool is easier to get. A practical approval route:
| Step | What to check | Who decides |
|---|---|---|
| 1. Geometry | Full ISO designation identical; fits the existing holder | Purchasing can check |
| 2. Application | Same ISO group, same operation (finishing, medium, roughing) | Process engineer |
| 3. Maker’s recommendation | Maker’s cross-reference chart or technical advice | Supplier obtains, engineer reviews |
| 4. Trial | Test on your actual part and machine, record tool life and finish | Process engineer |
| 5. Approval | Add the substitute to the approved-alternatives column of the item list | Technical owner |
Once a substitute is approved, it can be bought without repeating the trial. If it is not approved, a supplier should not send it.
For round tools, the same logic applies: diameter, length, shank, coating and flute geometry first, then a trial. For taps, also confirm the thread standard and tolerance class, because a tap that cuts the right nominal size in the wrong class produces threads that gauges reject.
💬 Want substitutes proposed against your process, not just against a code? Tell us the workpiece material and the operation, and we will put the maker’s alternatives in front of your engineer. See MRO and factory consumables.
Abrasives: specify the product, the grit and the speed
For abrasives, the item list must hold the product type, the abrasive grain, the grit, the dimensions and, for bonded wheels, the maximum operating speed marked on the product, because a wheel that fits the spindle but is rated for a lower speed is a safety risk, not a quality issue.
Abrasives fall into three families, each specified differently:
| Family | Examples | Key fields on the item list |
|---|---|---|
| Bonded abrasives | Grinding wheels, cut-off wheels, depressed-centre discs | Dimensions and bore, abrasive grain, grit, hardness grade, bond, maximum operating speed |
| Coated abrasives | Sanding belts, sheets, discs, flap discs | Backing, abrasive grain, grit (P-number), dimensions, fixing (hook-and-loop, PSA) |
| Superabrasives | Diamond and CBN wheels | Maker’s full specification; usually bought from the maker’s own range |
Grit sizes for coated abrasives use the P scale. ISO 6344-2:2021 covers the macrogrit sizes P12 to P220, and ISO 6344-3:2021 the microgrit sizes P240 to P5000. A grit number without the P prefix may be on a different scale, so record the prefix on the item list.
Safety of bonded abrasive wheels
In Europe, EN 12413:2019, Safety requirements for bonded abrasive products, applies to rotating bonded abrasive products and sets requirements and tests to reduce the hazards arising from their design and use. It does not cover superabrasive or coated abrasive products. Other markets have their own rules. If your factory follows a specific standard or customer requirement, record it on the item list and ask the supplier to confirm it per line.
What to check on receipt, whatever market you are in:
- the maximum operating speed marked on the wheel against the spindle speed of the machine it will go on;
- dimensions and bore against the machine and flanges;
- any expiry or use-by marking, where the maker gives one;
- intact original packaging, with no cracks or chips on the wheel.
Makers whose abrasives buyers often specify include 3M, Norton, Klingspor and Noritake. As with inserts, these are examples only; naming them does not imply any relationship with, or authorisation from, these makers.
Counterfeit and grey-market tools
Cutting tools and abrasives are copied. Buy branded tools through a channel you can trace back to the maker, and treat a price far below every other offer for the same code as a reason to ask where the goods came from.
Copied inserts can be hard to tell from genuine ones by eye. Signs worth a second look:
- packaging with a different label layout from your existing stock, or missing lot codes;
- an insert grade that does not appear in the maker’s current catalogue;
- inconsistent tool life between boxes of the “same” item;
- a seller who will not say where the goods were bought.
The general method for avoiding counterfeit parts, including how to trace the channel and when to ask a maker to verify, is set out in avoiding counterfeit bearings and industrial parts. Where the tools must be genuine Japanese products shipped from Japan, see genuine Japanese industrial parts.
Stock, packaging units and ordering
Set stock levels for tools by edges or pieces consumed, order in the maker’s packaging unit, and keep inserts in the maker’s box until issued so that lot, grade and chipbreaker stay traceable.
Practical points for the stores team:
- Packaging unit. Inserts are typically sold in boxes of a fixed count set by the maker. Set the minimum stock in boxes.
- Issue rule. Issue by box, or record the grade and lot on any loose inserts. Loose inserts of similar codes are the usual source of mix-ups.
- Regrinding. Solid carbide drills and end mills may be reground. If you regrind, record it, because a reground tool is a different item for tool-life tracking.
- Stock-outs. A critical insert for a production part should be in the “critical” class of the item list, with a minimum level and a named person who reorders.
When several makers’ tools come from different origins, consolidating them into one delivery is covered in consolidating Asian suppliers into one shipment.
💬 Need inserts, drills and abrasives on one regular order? We source each line by maker code, check grade and suffix on arrival, and deliver against your item codes. Contact us about factory consumables.
Frequently asked questions
1. Is the ISO code enough to order an indexable insert?
No. The ISO 1832 code fixes shape, size, thickness and corner radius. The chipbreaker suffix and the grade are each maker’s own, and they decide how the insert cuts. Record all three on the item list.
2. Can I replace one maker’s grade with another maker’s grade?
Often, but only after checking. Match the ISO application group and the operation, get the maker’s cross-reference, then trial the substitute on your own part before approving it.
3. What does the P in a sanding grit number mean?
It marks the P scale used for coated abrasives, covered by ISO 6344-2 (P12 to P220) and ISO 6344-3 (P240 to P5000). Keep the prefix on the item list so that grit is not confused with another scale.
4. What should I check on a grinding wheel when it arrives?
The maximum operating speed marked on the wheel against the machine’s spindle speed, the dimensions and bore, any expiry marking the maker gives, and the condition of the wheel and its packaging.
5. How can I tell whether inserts are genuine?
Buy through a channel traceable to the maker, compare packaging and lot codes with known-genuine stock, and check that the grade is in the maker’s current catalogue. If doubts remain, ask the maker to verify through its local distributor or office.
Checked on 27 October 2026. Standards are cited by title and edition as listed by standards bodies; confirm the edition your customer or market requires before you rely on it.
Sources: ISO 1832:2017, Indexable inserts for cutting tools — Designation (iso.org/standard/69202.html; SIS listing SS-ISO 1832:2017). ISO 513:2012, Classification and application of hard cutting materials (iso.org/standard/59932.html). ISO 6344-2:2021 and ISO 6344-3:2021, Coated abrasives — grain size distribution (iso.org). EN 12413:2019, Safety requirements for bonded abrasive products (BSI and EVS listings). Insert dimensions for CNMG 120408 and examples of chipbreaker suffixes from the makers’ published product pages. Workpiece material groups as described by Sandvik Coromant (sandvik.coromant.com, Workpiece materials).