1970 Development of Polycrystalline Diamond (PCD) and CBN (PCBN)

Opening New Horizons for a Multitude of Applications

BZN 8200 Compacts, milling of lathe rails, Hardened Steel 63 Rc

The third family of superabrasives, polycrystalline diamond and CBN products was introduced in 1970 for cutting tool machining applications of nonferrous and nonmetallic materials, especially where the workpiece itself is abrasive. Two of the most important properties of these materials are long-wearing cutting edges and abrasion resistance. Polycrystalline tool blanks are made by sintering and integrally bonding either diamond or CBN particles with a tungsten carbide substrate using a high temperature / high pressure process.

Here, the diamond or CBN is randomly oriented, making for a uniform tool surface. The tool blanks are finished in various sizes and shapes by using specialized cutting, grinding and lapping techniques. GE offers a family of such “Compacts” products, each designed for a specific application. Machining applications include: ferrous and nonferrous metal, tungsten carbide and nonmetallics like plastic, rubber, fiberglass, ceramics, carbon and graphite. Dressing products are used to form and dress aluminum oxide and silicon carbide grinding wheels; wire dies are used for drawing non-ferrous and ferrous wire; while a line of polycrystalline drill diamond serves the drilling industry.

Introduction of Compax* Polycrystalline Diamond Tool Blanks for Machining

Figure 1

Polycrystalline diamond blanks consist of multiple diamond crystals sintered together with a tungsten carbide substrate. PCD blanks have advantageous uses as cutting tools for nonferrous materials and can be used at exceedingly high cutting speeds and material removal rates.

BZN* Compacts Tool Inserts for Machining Hardened Ferrous Materials

Figure 2

Polycrystalline cubic boron nitride tool inserts, which were introduced commercially in 1975, consist of a layer of polycrystalline CBN sintered with tungsten carbide substrate to form an integral blank. These can be brazed directly to tool shanks or used as indexable inserts to machine high temperature alloys and hardened ferrous materials. A new product in which ceramic grains are added to the sintering process, was introduced in 1991. The ceramic component of this product provides high chemical stability while the PCBN supplies superior hardness and resistance to abrasion and chipping. This product holds tighter tolerances than ceramic tools, while providing resistance to the chemical reaction that can cause cratering in other CBN tools. These new CBN/ceramic inserts perform at high speeds and achieve material removal rates from 4 - 10 x over conventional grinding.

Figure 3

Compax* Diamond Blanks for Wire Drawing

The development of diamond die blanks in 1974 revolutionized the copper wire industry by providing longer die life, improved productivity, consistent surface finish and better dimensional control. These blanks currently offer significant advantages over dies made with either single-crystal mined diamonds or tungsten carbide in the drawing of ferrous wire.

Stratapax* Drill Blanks for Geological Drilling Applications

Drill bit with Stratapax Drill Blanks - kleiner!

PCD drill blanks were introduced in 1976 for drilling applications. They are attached to bit bodies used in drilling wells on and offshore. Today they are also enjoying success in mining applications. PCD drill blanks consist of a layer of polycrystalline diamond integrally bonded to a cemented tungsten carbide substrate, giving a combination of back-up strength, protection against gross fractures and abrasion resistance. The cutting edges of the self-sharpening PCD blanks allow for more rapid penetration of geological formations than with traditional crushing or fracturing methods.

Geoset* Drill Diamond – a Thermally Stable Polycrystalline Diamond for Drill Bits

Thermally stable drill diamond, introduced in 1982, makes possible core bits that reach new levels of performance in soft-to-medium-hard formations. The large, tough cutting edges of thermally stable drill diamonds remain sharp throughout the life of the bit because their polycrystalline structure allows the crystals to be continuously exposed during drilling. Thermally stable drill diamond can be used both as cutting edges and excellent gauge protection on downhole tools. Bits using thermally stable drill diamond demonstrate excellent core quality at rapid penetration rates.

top