Resin Bond vs Metal Bond Grinding Wheels: How to Choose
Diamond grinding wheels are bought on three attributes that barely matter — diameter, bore and thickness — and specified on three that decide everything: bond type, diamond concentration and grit size.
The three bond families
Resin bond
Phenolic resin holds the diamond. The bond is relatively soft and friable, which means it releases dull grit readily and runs cool.
Use it for: carbide tool grinding, PCD and CBN tooling, precision finishing where heat damage to the workpiece is the risk, and any application where surface finish matters more than stock removal.
Do not use it for: heavy stock removal on hard steel, or any wet application with aggressive coolants that attack the resin.
Metal bond
A metal matrix — typically bronze, cobalt or a copper-tin mix — sintered around the diamond. Hard, durable, and it holds grit until it genuinely dulls.
Use it for: glass edging, ceramic tile, stone, concrete, and any high-volume application where wheel life dominates the cost calculation.
Do not use it for: heat-sensitive workpieces, or precision finishing where the hard bond will not expose fresh grit fast enough.
Electroplated
A single layer of diamond, nickel-bonded to a steel body. Not a matrix at all — the diamond sits on the surface.
Use it for: complex profiles, small form tools, and any shape that cannot be pressed and sintered. Very fast cutting, no dressing needed.
Do not use it for: high-load applications, because there is only one layer of diamond and once it is gone the tool is finished.
Concentration: the number that is usually misunderstood
Concentration 100 means 4.4 carat of diamond per cubic centimetre of abrasive layer. It is a fixed reference point, and concentration values are expressed relative to it — 75, 100, 125, 150.
Higher concentration does not automatically mean longer life. It means more cutting points per unit area, which means:
- lower load per particle, so each grit lasts longer,
- but a harder time exposing fresh grit, because there is more diamond crowding the bond surface.
For resin bond precision work, 75 to 100 is typical. For metal bond glass and stone, 100 to 125. Above 150 is a specialist choice, and is usually compensating for a bond that cannot hold grit properly.
Grit size: match it to the finish, not the wheel
Grit selection follows the required surface finish and the material, in that order.
| Grit | Typical use |
|---|---|
| D64 and coarser | heavy stock removal, rough grinding |
| D46 – D54 | general carbide grinding, edge preparation |
| D20 – D30 | fine finishing, PCD edge work |
| D7 – D15 | polishing, mirror finish on carbide |
Going one grit finer than necessary costs cycle time and does not improve a finish nobody is measuring.
The specification a factory needs
To quote a wheel that will actually work, a factory needs:
- Machine — spindle rpm, and whether it is a manual or CNC setup.
- Workpiece material and its hardness.
- Required finish (Ra, or a description of what “good” looks like).
- Coolant — flood, mist, or dry.
- Stock to be removed per pass.
Diameter and bore are the last things to mention, because almost any diameter can be made. The five items above determine whether the wheel works.
The mistake we see most
Buyers specify a wheel by copying a part number from a catalogue, then wonder why the finish differs. The catalogue wheel was specified for a different machine, a different coolant and a different workpiece. The part number carries none of that.
Send the five items. The part number is not a specification.
Related reading
Specifying a diamond grinding wheel and want it matched to your machine? Send us the five parameters — we will come back with a bond and a grit, not a catalogue number.
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Tell us the specification. Three to five factory quotes come back within five working days.