Case of resin diamond grinding wheel for grinding tungsten carbide inserts

Tungsten carbide is one of the hardest and most wear-resistant materials used in modern manufacturing. It’s widely applied in cutting tools, dies, wear parts, and precision inserts for machining metals and composites. However, its extreme hardness—second only to diamond—makes it very difficult to machine or finish using conventional abrasives.

To achieve the required precision and surface finish on tungsten carbide inserts, diamond grinding wheels are the industry standard. Among the different bonding systems available—such as metal, vitrified, and electroplated—the resin bond diamond grinding wheel has become a preferred choice for finishing and sharpening tungsten carbide inserts due to its excellent balance between cutting performance, surface finish, and tool life.

Understanding Tungsten Carbide Inserts

What Are Tungsten Carbide Inserts?

Tungsten carbide (WC) inserts are precision-engineered cutting tool components made by powder metallurgy. They consist of tungsten carbide particles bound together by a metallic cobalt binder (typically 6–15%). This combination provides exceptional hardness, wear resistance, and toughness—ideal for machining hard materials like steels, cast iron, and alloys.

Tungsten carbide inserts are used in turning, milling, drilling, and other metal-cutting applications. After sintering, the inserts undergo grinding to achieve the required geometry, dimensional accuracy, and cutting-edge sharpness.

Challenges in Grinding Tungsten Carbide

Grinding tungsten carbide presents several challenges:

* Extreme hardness (above 90 HRA) requires a superabrasive—typically diamond—for efficient material removal.

* Brittleness means that improper grinding can cause microcracks or chipping on the insert edges.

* Thermal damage can degrade the cobalt binder, leading to reduced tool life.

* High material removal resistance leads to faster wheel wear and potential loading.

Hence, selecting the right wheel type and optimizing grinding parameters are crucial for achieving precision and efficiency.

Characteristics of Resin Bond Diamond Grinding Wheels

What Is a Resin Bond Diamond Wheel?

A resin bond diamond wheel is made by mixing diamond abrasive grains with a resin binder (usually phenolic or polyimide), then pressing and curing the mixture into a wheel shape.

The resin bond acts as a flexible matrix, which holds the diamond grains and gradually releases worn grains to expose new sharp cutting edges.

 Key Features of resin diamond grinding wheel

* Good self-sharpening ability: The bond wears slightly during grinding, continuously exposing new diamond edges.

* Fine surface finish: The elastic resin bond produces less vibration and cutting marks, ideal for precision finishing.

* Cool grinding: Resin bonds generate less heat compared to metal bonds, reducing the risk of thermal damage to tungsten carbide.

* Lower grinding force: The soft bond helps minimize tool pressure, important for delicate edges.

* Easier to true and dress: Resin wheels can be easily shaped using silicon carbide or diamond dressing sticks.

Typical Applications

Resin diamond wheels are widely used for:

* Sharpening and finishing tungsten carbide cutting tools and inserts.

* Grinding PCD/PCBN tools.

* Processing hard ceramics, cermets, and glass.

* Precision optical and electronic components.

When used for tungsten carbide inserts, resin diamond wheels excel in edge sharpening, flank surface grinding, and rake surface polishing.

Grinding Tungsten Carbide Inserts with Resin Diamond Wheels

Grinding Process Overview

The grinding of tungsten carbide inserts usually involves multiple stages:

* Rough grinding: High material removal rate to achieve near-final geometry.

* Semi-finishing: Improve geometry and remove grinding marks.

* Finishing / polishing: Achieve mirror-like surface finish and precise dimensional accuracy.

Each stage may use a different grit size, bond hardness, and wheel shape.

Importance of Coolant

Adequate coolant flow is critical during grinding. It:

* Removes grinding heat to prevent cobalt binder oxidation.

* Flushes away chips and debris, preventing wheel loading.

* Extends wheel life and improves surface finish.

A high-pressure, properly directed coolant jet at the grinding zone is recommended.

Edge Protection

When grinding insert cutting edges, avoid aggressive feeds or excessive pressure. A dull or loaded wheel can cause edge micro-chipping. Periodic dressing maintains the wheel sharpness and consistent performance.

Common Problems and Solutions