A cartridge is the part of a tool holder that does the cutting, with the shank removed. It bolts straight into a boring head, a special body or a multi-point tool, and it takes an ordinary insert. If you have ever priced a custom cutting unit and flinched, this is the article that explains the alternative—and why the code on a cartridge is one you already know how to read.
What a cartridge actually is
An indexable tool holder is two things welded into one idea: a shank that clamps in the turret, and a pocket that holds and supports the insert. A cartridge is the second half on its own.
Instead of a shank it has a mounting face and fixing holes, so the cutting unit is mounted directly into the body of another tool—a boring head, a facing head, a special block, a multi-point cutter. The body provides the rigidity and the positioning; the cartridge provides the seat, the clamp and the geometry.
That is the whole concept, and everything useful about cartridges follows from it.
You already know how to read the code
This is the part that surprises people. A cartridge is not coded in some separate system. Look at these four references from our range:
- MCLNR10CA-3C—95° lead angle, CN 32 insert
- SCLCR10CA-11—95° lead angle, CC 21 insert
- PTGNL10CA-11—90° lead angle, TNMG 33 insert
- CSKPR10CA-09—75° lead angle, SP 32 insert
Those are ISO/ANSI tool holder designations. Same five positions, same meanings: clamping system, insert shape, tool style, insert clearance, hand. If you can read MCLNR 16-4D on a turning holder, you can read MCLNR on a cartridge. The only difference is what is behind the pocket.
The four clamping systems show up exactly as you would expect across our 228 references:
| First letter | Clamping | Typical use in a cartridge |
|---|---|---|
| M | Top clamp and pin | Maximum insert security for heavy or interrupted cuts |
| S | Screw clamp | The compact option—nothing protrudes above the insert |
| P | Lever lock | Fast indexing without a clamp arm in the chip path |
| C | Top clamp | Inserts without a center hole |
On a cartridge the choice of clamping system matters more than on a holder, not less. There is less body behind the seat, and a clamp that protrudes into a boring head's chip space becomes a chip-packing problem in a place you cannot see.
Why a cartridge instead of a tool holder
Three situations, and in all three a conventional holder simply cannot be fitted.
Boring heads and facing heads. The cutting unit has to sit on a slide that moves radially. There is no turret pocket to clamp a shank into—the head is the body, and the cartridge bolts to it.
Multi-point tooling. A line-boring bar or a special cutter carrying several cutting edges at different diameters cannot be built from shank tools. Each station is a cartridge, and each one can be a different geometry if the job calls for it.
Special and purpose-built tools. When a fixture-mounted or purpose-made tool needs a real indexable seat, the alternative to a cartridge is a machined pocket in the body itself. That pocket is a one-off: if it wears or a clamp screw strips, the repair is the whole body.
This is the argument that matters commercially. A cartridge makes the wearing part replaceable. The seat, the clamp and the screw all live in a component you can unbolt, and the expensive body outlives them.
The range, and what it tells you
We stock 228 cartridge references across 66 families, right and left hand throughout. Two numbers describe the spread better than a list:
Eight lead angles: 30°, 45°, 60°, 75°, 85°, 90°, 93° and 95°. That is a wider spread of approach angles than most shank-holder ranges carry, and it is not decoration. In a boring head the lead angle decides how cutting force splits between radial and axial—and radial force is what pushes a slide off size.
Twenty-three insert sizes, across the negative families (CNMG, SNMG, TNMG, WNMG, DNMG) and the positive ones (CC, SC, TC, SP, TP). The negative sizes carry the roughing work; the positive ones are where a light cut and a good finish matter, which in a boring head is most of the time.
The largest single groups in our range are the 90° families—66 references—followed by 75° with 44 and 95° with 30. A 90° lead pushes almost all of its force axially, which is exactly what you want when a radial slide is holding the diameter.
Ordering without guessing
A cartridge has to satisfy the body it bolts into and the cut it takes, so check in this order:
- The mounting. The body decides this, not you. Dimensions are published for every reference—match them to the head or block before anything else
- The insert. Preferably one you already stock. There is no advantage in a cartridge that introduces a twenty-fourth insert size into the crib
- The lead angle. For a boring or facing head, favour a lead that keeps force axial and off the slide
- The hand. Every family is available right and left; on a multi-point tool you may need both
- The clamping system. Security for heavy cuts, compactness where chip space is tight
If you are replacing a cartridge in an existing head, the fastest route is the code stamped on the old one—it is a standard designation, and it tells us the geometry even if the brand on it is not one we carry.
Where cartridges sit next to the rest of the line
Cartridges complete a picture that runs through several of these articles. A shank tool holder puts the seat in the turret. A boring bar puts it at the end of a bar reaching into a bore. PSC modular tooling puts it on the end of a coupling you can rebuild into any chain. A cartridge puts it wherever the body needs it, and asks nothing except a mounting face. In the catalog those are turning tool holders, boring bars, PSC modular tooling and cartridges.
The insert code is the same in all four cases. If you have not read it yet, turning insert designations explained covers the one code that ties the whole system together.
Tooling for this job
- Canela Cartridges — 228 cartridges, 66 families, right and left hand, lead angles from 30 to 95 degrees.
- Canela Tool Blocks — the bodies cartridges bolt into.
- Boring Bars — 845 bars when the seat needs to travel down a bore instead.
- Turning Inserts — the same insert code, whichever way the seat gets to the cut.
- Canela PSC Modular Tooling — 1,553 references for building the chain behind the cutting end.
FAQ
What is an indexable cartridge?
It is the cutting end of a tool holder without the shank: a seat, a clamp and a geometry on a mounting face, designed to bolt directly into the body of another tool such as a boring head, a facing head, a multi-point bar or a purpose-built block. The body supplies the rigidity and the positioning; the cartridge supplies the insert pocket.
How do I read a cartridge designation?
The same way you read a turning tool holder code. A cartridge such as MCLNR or SCLCR uses the standard five positions: clamping system, insert shape, tool style which sets the lead angle, insert clearance angle, and hand. There is no separate cartridge code system to learn.
Why use a cartridge instead of machining the insert pocket into the body?
Because it makes the wearing part replaceable. A pocket cut into the body is a one-off: when the seat wears or a clamp screw strips, the repair involves the whole body. A cartridge puts the seat, the clamp and the screw into a component you can unbolt and replace, so the expensive body outlives the consumable parts.
Do cartridges take special inserts?
No, and that is the main reason to use them. Every cartridge in our range is sized to a standard insert, across the negative families such as CNMG, SNMG, TNMG, WNMG and DNMG and the positive ones such as CC, SC, TC, SP and TP. A special tool built around cartridges runs on inserts you can order from stock.
Which lead angle should a cartridge in a boring head have?
Usually one that keeps cutting force axial rather than radial, because radial force is what pushes a radial slide off size. That is why 90 degree families are the largest group in our range, with 66 of 228 references, followed by 75 degrees and 95 degrees. Our range covers eight lead angles from 30 to 95 degrees.
Can I get a cartridge in left hand?
Yes. All 66 families in our range are stocked in both right and left hand. On multi-point tooling you often need both on the same body.
I need to replace a cartridge in an existing head. What do you need from me?
The code stamped on the old cartridge, plus the mounting dimensions if you have them. The designation is a standard one, so it describes the geometry even when the brand on the part is not one we carry.
The full range is online: 228 indexable cartridges, right and left hand, with dimensions and the insert each one takes published on every page. Replacing one in an existing head? Send us the code stamped on it and we will match the geometry.
Family counts, lead angles, insert sizes and hand availability in this article are taken from the FM Carbide catalog as stocked. Dimensions for each reference follow the Canela catalog.
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