Home > Guide to selecting grinding wheels for sharpening PCD/PCBN tools

Guide to selecting grinding wheels for sharpening PCD/PCBN tools

Tools with polycrystalline diamond (PCD) and cubic boron nitride (PCBN) tips are exceptionally durable but require occasional sharpening.

Compared to conventional tool materials, sharpening tools made from PCD or PCBN requires a different approach in terms of grinding methods and abrasive characteristics. Sharpening polycrystalline tools poses a challenging task for both users and abrasive manufacturers.

To ensure the proper sharpening process of PCD/PCBN tools, the following are necessary:

-A precise grinder with adequate structural rigidity and vibration damping system, ensuring high precision required for sharpening polycrystalline tools.
-Specially designed grinding wheel for high-efficiency and precision machining, ensuring excellent edge quality.

PCD (Polycrystalline Diamond) and PCBN (Polycrystalline Cubic Boron Nitride) are types of materials used for cutting tools.

PCD (polycrystalline diamond) is a synthetic superhard material used for manufacturing cutting tools. It consists of very hard micron-sized diamond grains bonded together with a metal binder and mounted on a tungsten carbide substrate. This combination results in a material with excellent properties widely used in machining.

PCD is primarily used for processing materials such as:

-ceramics
-aluminum
-copper
-laminates
-wood
-plastics
-rubber

PCBN polycrystalline cubic boron nitride (PCBN) is a synthetic material produced similarly to PCD, but instead of diamond, micron-sized grains of cubic boron nitride (CBN) are used.

PCBN (Polycrystalline Cubic Boron Nitride) is primarily used for processing materials such as:
-Tool steels
-High-speed steel (HSS)
-High-alloy steels

Grinding wheel selection

The shape and dimensions of the grinding wheel.
The shape of the grinding tool is selected based on the grinding task, grinder construction, and processing conditions. The dimensions of the grinding wheel are chosen according to the size and power of the machine as well as the dimensions of the workpiece being processed.

Particle size
The most important criterion for selecting a grinding wheel is the expected quality of the ground surface of the cutting edge. In grinding wheels for sharpening PCD and PCBN tools, four basic particle sizes are used, as listed in the table below.

Selection of grain size

Grain size	Type of processing	Application
D22	Rough	Regenerative grinding – profiling the edge and sharpening heavily worn inserts.
D15	universal	Standard grain size – enables high sharpening efficiency and good quality of sharpened surfaces with the use of additional spark-out passes.
D9	finishing	Finish grinding – achieving very high quality surfaces of the cutting edge of the insert.
D6	superfinish	Super-precision grinding – the ability to achieve excellent quality of sharpened surfaces.

Other parameters
Other grinding wheel parameters (grain concentration, hardness, structure) are individually selected for each user depending on the type of processing, grinder used, and properties of the tool being sharpened.

Operation of grinding wheels

Selection of processing parameters
When sharpening PCD and PCBN tools, special attention must be paid to the correct selection of sharpening process parameters. A diamond grinding wheel, made with the most advanced technology, will never be effective if the conditions of its application and/or processing parameters are chosen incorrectly.

Parameters

Grinding speed: 20 m/s – recommended; 15÷30 m/s – permissible

Allowance:

ough grinding: 0.02-0.05 mm/pass

Standard grinding: 0.01-0.025 mm/pass

Finish grinding: 0.005-0.01 mm/pass

Oscillation frequency:

60 cycles per minute – recommended

50-120 cycles per minute – permissible

Number of spark-out passes: 3-8

Recommended type of dresser: Electro-corundum dresser 5410-20x10x100 99A 320 J7V

Coolant: Oil-water emulsion 3-5%

Note: Wheel dressing must always be performed outside the machining zone.

Adjustment procedures
If the grinding wheel seems too hard, reduce the grinding speed to 15-18 m/s and perform dressing more frequently. If the grinding wheel wears out too quickly, increase the grinding speed to 22-30 m/s.

Ordering

Choosing a grinding wheel
-The scheme for selecting a grinding wheel is as follows:
-Determine geometric parameters such as: type of grinding wheel, workpiece dimensions, and hole diameter.
Depending on the type of processing, select the grain size.

Example order No. 1

To order a grinding wheel for universal processing with the following parameters:

-Type of grinding wheel: 6A2 VCM
-Diameter: 150 mm
-Width of the working layer: 5 mm
-Height of the working layer: 10 mm
-Bore diameter: 40 mm
-Grain size: D15
You should provide the following designation in the order:

6A2 150x5x10x40 VCM D15

Example order No. 2

To order a finishing grinding wheel with the following parameters:

Type of grinding wheel: 11A2 VCM
Diameter: 250 mm
Width of the working layer: 6 mm
Height of the working layer: 8 mm
Bore diameter: 40 mm
Grain size: D9
You should provide the following designation in the order:

11A2 250x6x8x40 VCM D9

Placing an order

Due to the need for precise adaptation of the grinding wheel characteristics to the application conditions, please include in the order the type of material and processing, as well as the conditions and type of machine for which the grinding wheels are being selected. This will allow us to tailor the grinding wheel to your needs to the fullest extent possible.

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INTER-DIAMENT® Kacprzycki Sp.j.
st. Chełmońskiego 30
05-825 Grodzisk Mazowiecki, Poland

+48 22 755 69 83
+48 22 755 58 78
+48 22 734 18 63

handlowy@inter-diament.com.pl
inter@inter-diament.com.pl