PCD & PCBN Grinding Problems: What Goes Wrong and How to Fix It

Grinding PCD and PCBN tools can feel like a constant fight against edge chipping, wheel glazing, slow cycle times and unpredictable tool life. The good news is that most of these problems have clear causes — and even clearer solutions. In almost every case, the right diamond grinding wheel, combined with correct parameters, will eliminate the issue.

Here are the most common problems our customers share with us, and the solutions that work.

Problem 1: Excessive edge chipping

What you see: The cutting edge of your PCD or PCBN insert shows visible chips after grinding. Under magnification, chipping can exceed 10 µm, making the tool unusable for finishing work.

Why it happens:

• Grit size is too coarse for the finishing pass. A D46 or D54 wheel will remove stock fast but leaves a rough edge.

• Depth of cut is too high during the final passes.

• The wheel bond is too hard, holding dull grains that rub instead of cut.

• Machine vibration or worn spindle bearings transfer movement to the edge.

How to fix it:

• Use the right grit: For final passes, switch to a D10–D15 vitrified diamond wheel. This alone brings chipping below 10 µm in most setups.

• Reduce your finish depth of cut: Stay at 0.005–0.01 mm per pass.

• Run spark‑out passes: 3 to 8 passes with zero infeed clean up residual deflection and noticeably improve edge quality.

• Check the machine: If chipping persists across different wheels, test spindle runout and balance.

Why our vitrified diamond wheels help: Vitrified bonds release dull grains naturally, so the wheel stays sharp and cuts freely without excessive rubbing that can chip the edge.

Problem 2: Burn marks or vertical streaks

What you see: Brownish or blue discoloration on the flank face, or vertical scratches running along the ground surface.

Why it happens:

• The wheel face is loaded with swarf and dull diamond grit, so it rubs instead of cutting.

• Coolant is insufficient or poorly directed.

• Depth of cut is too heavy, generating excessive heat.

• Wheel speed is too high, causing thermal damage.

How to fix it:

• Dress the wheel: Use a standard dressing stick to expose fresh diamond. Do this before burn marks appear, not after they have ruined a batch.

• Check coolant flow: Ensure a water‑based emulsion (3–5%) is hitting the grinding zone with enough pressure. Aim for at least 60 L/min if your machine supports it.

• Lower the depth of cut and increase oscillation frequency to spread wear evenly.

• Reduce wheel speed slightly if burning continues.

Why our vitrified diamond wheels help: The natural porosity of vitrified bonds helps carry coolant into the grind zone and evacuate chips, running cooler than dense metal or resin wheels.

Problem 3: Wheel wears out too fast

What you see: Diamond abrasive disappears quickly, the wheel diameter reduces fast, and you are dressing or replacing the wheel far more often than expected.

Why it happens:

• The bond grade is too soft for your application. The bond releases grains before they have done their work.

• Wheel speed is too low, so individual grains take heavier cuts and fracture prematurely.

• The abrasive grit size is too fine for the amount of stock you are removing.

How to fix it:

• Ask for a harder bond grade. We can match the bond hardness to your material and machine.

• Increase wheel speed to the recommended 20–25 m/s range. At these speeds, the wheel acts harder, reducing grain pull‑out, and individual grains see gentler impact loads.

• Use a coarser grit for roughing. If you are removing 0.3 mm or more of material, start with D20–D46, not D10.

Why our vitrified diamond wheels help: We engineer our wheel formulations to balance wear resistance and free‑cutting, so you get a long service life without sacrificing edge quality.

Problem 4: Wheel glazing and poor cutting action

What you see: The wheel looks shiny and smooth, grinding time increases, and you have to push harder to make it cut. The tool may show burn marks.

Why it happens:

• The bond is too hard for the specific PCD or PCBN grade you are grinding.

• Dressing is too infrequent, and dull diamond grit stays in the bond.

• In cases where a metal bond wheel is being used, this is a classic symptom of poor self‑sharpening.

How to fix it:

• Switch to a vitrified bond wheel if you are currently using metal bond. Vitrified wheels self‑sharpen continuously and will not glaze under normal conditions.

• Dress more often. A quick touch with a dressing stick restores cutting action immediately.

• Slightly increase oscillation. Oscillating distributes the wear over a wider wheel surface and helps prevent localised loading.

Problem 5: Chatter marks or waviness

What you see: Regular wavy patterns along the ground surface, or audible vibration during grinding.

Why it happens:

• The wheel is out of balance.

• The spindle has excessive runout.

• The grinding pressure is inconsistent, often due to an unsuitable bond type or wrong infeed strategy.

How to fix it:

• Balance the wheel properly before mounting.

• Verify spindle runout is under 0.005 mm.

• Infeed only outside the cutting zone. Suddenly engaging the wheel while it contacts the tool creates impact loads that excite vibration.

• Use a wheel with the right bond elasticity. Vitrified wheels have high rigidity and resist deflection, which helps prevent waviness in profile holding.

Problem 6: Inconsistent edge quality from tool to tool

What you see: One insert comes out sharp, the next has slight chipping or a dull stripe. No clear pattern.

Why it happens:

• Machine condition drifts (spindle wear, axis play).

• Dressing is performed inconsistently.

• The wheel specification is borderline for the material being ground, so small changes in material hardness cause quality swings.

• Operator technique varies from cycle to cycle.

How to fix it:

• Standardize the process: Use one proven vitrified diamond wheel specification for all tools of the same type.

• Dress at set intervals, not by guess.

• Document parameters (speed, infeed, passes, spark‑outs) and ensure every operator follows them.

• If the issue continues, we can review your setup and recommend a wheel grade that handles batch‑to‑batch material variations more robustly.

Problem 7: Fast diamond wear when grinding PCBN

What you see: When grinding PCBN inserts, the diamond wheel appears to wear unusually quickly, almost as if the PCBN is “eating” the diamond.

Why it happens:

• The PCBN grade contains metallic binder phases that, under high grinding temperature, can cause accelerated diamond wear through chemical interaction. This is normal behaviour and not a fault of the wheel.

• Insufficient cooling allows the temperature at the contact point to rise too high.

How to fix it:

• Boost coolant flow and pressure.

• Reduce depth of cut per pass to keep grinding temperatures down.

• Ensure wheel speed is in the 15–20 m/s range. Too high a speed adds unnecessary heat.

• Diamond remains the correct abrasive for PCBN; switching to CBN is not a solution.

Summary: one wheel type solves most problems

The pattern in these solutions is clear: a well‑specified vitrified diamond grinding wheel, correctly dressed and run with sensible parameters, eliminates the majority of PCD and PCBN grinding issues. It stays sharp, runs cool, holds its profile, and gives you consistent edge quality day after day.

If you are fighting chipping, burns, short wheel life or cycle‑time bottlenecks, we can help you dial in the right wheel and parameters.

Get your PCD and PCBN grinding under control. Tell us your tool type, machine and the biggest problem you face, and we will send you a vitrified diamond wheel recommendation that fits your process.