Sintering Process Types in Diamond Tool Manufacturing

Introduction

Diamond tools have various applications in several industries such as construction, mining, and woodworking. However, the manufacturing process of these tools plays a crucial role in ensuring their quality and durability. Sintering is one of the most significant processes involved in the production of diamond tools. This paper presents an overview of the sintering techniques used in diamond tool manufacturing with a particular focus on cold-press sintering, pre-sintering, and hot-press sintering.

Cold-press sintering

Cold-press sintering, also called dry pressing, is a powder metallurgy technique used to fabricate green compacts. In this process, diamond powder is compacted to a desired shape and size at ambient temperature under a specific compressive force. The compacted green body is then sintered in a furnace using a vacuum or an inert atmosphere.

Cold-press sintering is suitable for the production of small, thin-walled, and complex-shaped diamond tools. However, the green compacts are relatively fragile and prone to cracking, resulting in a low sintered density. Therefore, cold-press sintering is often combined with other sintering techniques to enhance the density and strength of the diamond tool.

Pre-sintering

Pre-sintering is a process in which diamond powder is partially sintered at a lower temperature and then cooled to room temperature. The cooled body is further compacted and then sintered again at a higher temperature. This process is also called two-stage sintering or intermediate sintering. Pre-sintering helps to eliminate trapped air and other impurities that may hinder the final sintering process. It also reduces the overall sintering time and improves the dimensional stability of the diamond tool.

Pre-sintering is commonly used in the production of diamond cutting tools, such as saw blades and drill bits. The process requires careful control of the sintering temperature, time, and atmosphere to achieve the desired sintered density and strength.

Hot-press sintering

Hot-press sintering is a high-pressure, high-temperature sintering technique used to fabricate dense and strong diamond tools. In this process, diamond powder is compacted under a uniaxial or isostatic pressure at a high temperature of about 1500°C in a vacuum or an inert gas atmosphere. The high pressure and temperature create a high degree of atomic diffusion and bonding between diamond particles, resulting in a nearly full sintering density.

Hot-press sintering is suitable for the production of large, thick-walled, and simple-shaped diamond tools. The process also allows the addition of certain metal powders or other additives to improve the sintered properties of the diamond tool, such as toughness and wear resistance.

Conclusion

In conclusion, sintering plays a crucial role in the production of diamond tools, and cold-press, pre-sintering, and hot-press sintering are the main techniques used in the industry. Cold-press sintering is used for small and complex-shaped diamond tools, while two-stage pre-sintering is used for larger and simpler tools. Hot-press sintering is used for large and thick-walled diamond tools that require high strength and density. Each technique requires careful control of the sintering parameters to achieve the desired sintered properties.