Principles and Characteristics of Hard Alloy Workpiece Forming Processes

Principles and Characteristics of Hard Alloy Workpiece Forming Processes

While various manufacturing methods exist for hard alloy workpieces, their fundamental principle remains consistent—formation through compression molding.

For example, depending on the workpiece's dimensions, shape complexity, and production batch, most cutting tools are formed using upper-and-lower pressing with rigid molds. During each pressing cycle, it is essential to ensure that the amount (both mass and volume) of powder fed into the mold cavity remains identical to maintain consistent workpiece weight and dimensions.

Since the powder's flowability is primarily determined by the size distribution of agglomerates and the properties of the organic binder, a molded part (or "green body") can be formed by applying a molding pressure of 10–80 ksi (thousand pounds per square foot) to the powder in the mold cavity.

Most importantly, tungsten carbide particles remain undeformed or unbroken even under extremely high forming pressures, while organic binders are pressed into the gaps between the particles, effectively securing their positions. Consequently, higher pressure results in tighter bonding of the tungsten carbide particles and greater workpiece density during pressing.

The forming characteristics of hard alloy powders vary depending on the content of metallic binders, the size and shape of tungsten carbide particles, degree of agglomeration, as well as the composition and dosage of organic binders. To provide quantitative information on the pressing properties of hard alloy powders, manufacturers typically establish a correlation between forming density and forming pressure; this data ensures that the supplied powder aligns with the tool manufacturer's forming process requirements.