Nickel coating weight is quoted as a percentage of the diamond weight: 30 percent or 56 percent are the two standards we produce. The choice is set by the bond, the grit size and how much holding force the tool needs. Titanium coating is a different tool altogether, and it solves a different problem.
What Coating Weight Means
A 56 percent nickel coating means the finished particle carries nickel equal to 56 percent of the original diamond weight. It is a weight gain figure, not a volume figure and not a thickness. Two coatings with the same weight percentage can differ in appearance, because the deposition method changes how the nickel is distributed.
Our own production covers both 30 percent and 56 percent, in electroplated and electroless versions. The published grade range is W7 and coarser for the 30 percent grade, and 20 microns and coarser for the 30%N, 56% and 56%N grades.
What The Nickel Is For
Nickel works mechanically. The layer is deliberately rough and spiky, so the bond grips the particle instead of relying on surface adhesion. Holding force goes up, pull-out goes down, and the tool keeps its cutting particles longer.
The second effect is conductivity. On electroplated tools the nickel layer helps the deposit build around the particle evenly, which is why coated grades are common on plated burrs and wire.
Our own product data puts the tool life gain at 20 to 35 percent against the same uncoated grade. That figure is a range because it depends on the bond and the process; it is not a promise for every application.
When 30 Percent Is Enough
Thirty percent is the standard choice for resin bond systems and for finer grit. On a resin wheel the bond does not need the same mechanical keying as a sintered metal bond, and a lighter coating keeps the particle free-cutting.
It is also the usual choice for diamond wire and for fine glass cutting tools, where a heavy coating would blunt the cutting edges and change the effective particle size.
When 56 Percent Pays For Itself
The heavier coating is for high-load bonds: sintered segments, metal bond tools that see impact, and coarser grit where pull-out is the main failure mode. The extra nickel is what keeps the particle in the matrix when the load tries to tear it out.
It costs more, and it changes the effective particle size. A 56 percent coated particle is larger than the same diamond uncoated, so the tool’s performance is not simply “the same grade with better retention”. If you are switching from uncoated to 56 percent on a process that is already at its tolerance, expect to re-check the size band.
Electroplated Versus Electroless
The N suffix in our grade naming means electroless. Electroless nickel deposits uniformly in all directions rather than only where the current reaches, so coating weight is more even across a batch and across each particle. On tools with complex geometry, that evenness is the reason to specify it.
Electroplated coating is the more common route and is entirely adequate for most bonded tool work. Specify electroless when uniformity matters more than cost.
Titanium Is Not A Heavier Nickel
Titanium coating solves a different problem, and it is not a question of weight. At sintering and grinding temperatures an uncoated diamond oxidises and graphitises. The titanium layer isolates the particle from that reaction, and it also wets to the metal matrix so the particle bonds instead of sitting in it as a loose inclusion.
The standard application is metal bond stone tooling: saw segments, blades and drills. The grade is ordered by the base diamond and its mesh size, for example an MBD grade at 80/100 with titanium coating, and the coating weight is confirmed before production.
On a steel-cutting or carbide-grinding job, titanium coating is not a substitute for choosing the right abrasive family. It improves retention; it does not change the chemistry between diamond and iron.
What To Specify
Four details in the purchase order prevent most coating problems: coating type (nickel or titanium), deposition route (electroplated or electroless), weight percentage, and the base diamond grade including its size band. Add the bond system and the tool type, and the recommendation becomes unambiguous.
Without the weight percentage, “nickel coated” is not a specification. Two suppliers can both ship nickel coated diamond and deliver tools that behave differently.
Next Step
Nickel-coated diamond: 30 percent from W7, 56 percent from 20 microns, electroplated and electroless. Titanium-coated diamond: W7 and coarser, for metal bond stone tooling.
Bond context: resin and vitrified bond wheels, electroplated tools, saw blades and core drills.