Saw blades and core drills are impact tools. The grit has to survive being clamped in a metal matrix and hit stone or concrete thousands of times. Selection is driven by toughness first, mesh second, coating third.
What The Segment Actually Does To The Grit
A diamond segment is a sintered metal block with diamond distributed through it. As the matrix wears, grit is exposed and cuts. Every particle therefore experiences three loads: clamping stress from the matrix, impact from the workpiece, and thermal cycling from the cut.
Grit that is too weak fractures before it cuts, so the segment polishes instead of sawing. Grit that is too strong for the application does not fracture at all, so the segment glazes and stops cutting. The right answer sits between those two failures, and it is different for granite, marble and reinforced concrete.
Mesh Range By Material
Coarse mesh is the norm because each particle must remove a meaningful chip. The bands below reflect common practice in stone and construction cutting.
| Material | Typical mesh | Why |
|---|---|---|
| Hard granite | 30/35 – 40/45 | Coarse grit for impact resistance in hard stone |
| Marble and soft stone | 40/45 – 50/60 | Finer grit cuts freely in soft material |
| Reinforced concrete | 30/35 – 40/45 | Coarse grit survives steel contact |
| Quarry block cutting | 30/35 – 50/60 | Depends on stone hardness and machine power |
| Core drills, general | 30/35 – 60/70 | Balance of penetration and life |
| Glass and tile drills | 60/70 – 325/400 | Fine grit for clean entry and low chipping |
MBD high-strength grit covers 18/20 to 500/600 mesh, which spans this entire range. Shape-corrected MBDS is available at 30 micrometres and coarser where uniform protrusion matters.
Toughness: The Number That Predicts Life
Toughness index measures how much grit survives a standard impact test. Measured values across our grades illustrate the spread clearly: MBD4 sits between about 44% and 69% depending on size, MBD6 around 66% to 68%, MBD8 between 69% and 80%, MBD10 at 82% to 84%, and MBD12 up to 86%. SMD25 reaches 88% and SMD30 up to 90% at the fine end.
For a granite blade, higher toughness usually means longer life. For a marble blade, a slightly lower-toughness grit can cut faster because it self-sharpens. Buying the highest number available is not automatically correct.
Coating: Titanium For Sintered Segments
Segments are sintered at temperatures where diamond oxidises at the surface. A titanium coating at 0.1% to 0.3% by weight limits oxygen access, improves heat transfer and reduces thermal damage. In saw segments this typically shows up as longer life rather than a faster initial cut.
Nickel coating, by contrast, is a retention coating for resin and plated tools. It is not the standard choice for a sintered segment, and its weight gain changes the effective grit size.
Concentration And Bond Hardness
Grit selection is only half the answer. Concentration and matrix hardness decide whether the grit is exposed at the right rate. A hard matrix with soft grit glazes; a soft matrix with hard grit sheds grit before it has cut.
When a customer reports a blade that “stopped cutting”, the diagnostic order is: check matrix wear first, then concentration, then grit. Replacing diamond when the matrix is the problem wastes a trial and produces a misleading conclusion.
Failure Patterns And What They Mean
| Symptom | Most likely cause | Action |
|---|---|---|
| Segment glazes, no cut | Grit too tough or matrix too hard | Lower TI grade or softer bond |
| Very short life, segment worn fast | Grit fracturing early | Raise TI, check coating |
| Uneven wear on one side | Coolant or machine alignment | Not a grit problem |
| Blade wobbles and cuts wide | Segment or core stiffness | Not a grit problem |
Common Mistakes
- Changing grit to fix a bond problem. If the segment glazes, the matrix is usually the first suspect, not the diamond.
- Using one grade across materials. Granite, marble and concrete want different toughness and mesh.
- Ignoring coating cost in the comparison. A titanium coating adds a small percentage to grit cost and can extend segment life well beyond it, but only in sintered bonds.
How To Verify
Ask for TI at the exact mesh size, an ash figure for the lot, and a morphology image. Then run a full segment life test on the actual stone, because lab impact tests rank grit but do not predict field life on a specific machine.
Next Step
Products: MBD, MBDS, HDHR. Applications: saw blades and core drills, stone and concrete cutting tools.
Related reading: toughness and crystal shape.