Analysis of Diamond Wire Saw Technology

Diamond wire saws, as a flexible, superhard material cutting tool, have a history of over 40 years. Initially developed with electroplating technology, they have evolved into manufacturing techniques dominated by sintering and brazing. From being limited to cutting soft stone, they are now widely used in granite quarries, cutting reinforced concrete, and cutting metal structures. With the continuous advancement of manufacturing technology, their application has expanded exponentially. Currently, the comprehensive performance of domestically produced diamond wire saws has reached internationally advanced levels, and their cost-effectiveness fully meets the needs of the domestic stone mining and plate processing industries. Many companies are even exporting their products in large quantities to Western countries such as Europe and the United States. With the rapid adoption of diamond wire saw machinery and cutting technology, my country's stone mining industry has entered the diamond wire saw era, and diamond wire saw manufacturers have experienced unprecedented growth. For example, in 2007, a domestic company produced over 30,000 meters of diamond wire saws, generating a production value of 15 million yuan and a profit of over 3 million yuan. This represents a doubling of production, output value, and profit compared to the previous year. Domestic diamond wire saw manufacturers have promoted the rapid progress of domestic diamond wire saw technology through independent innovation, laying a solid foundation for the further promotion and use of diamond wire saws.

 

 

 

With the growing use and expanding applications of diamond wire saws, diamond wire saw production technology has also been continuously advancing. To adapt to the rapidly developing domestic and international markets and catch up with international advanced standards, some domestic companies have continuously introduced new equipment and researched and applied new technologies in recent years. While production scale has continued to expand, product quality and efficiency have also been significantly improved, while production costs have continued to decline.

 

2.1 Granulation and Volumetric Automatic Cold Pressing Process

Currently, domestic wire saw manufacturers generally use ungranulated powder for manual cold pressing of wire beads. This results in low production efficiency, product quality that is easily affected by human factors, and a dusty working environment that is detrimental to human health.

 

In light of the numerous drawbacks of using ungranulated powder for cold pressing, a domestic company pioneered the use of powder granulation technology and supporting equipment in production practice. The powder granulation process involves adding powder to a container and using the high-speed rotation of a stirrer and cutting blades, combined with the spraying of an atomized solvent, to form granules. 10 kg of powder can be granulated in 20 minutes. After drying and screening, the granulated powder is formed into 30-80 mesh spherical granules with a molding efficiency exceeding 85%. The powder produced by this method has improved flowability. After the coated diamonds are mixed with the granulated powder, the diamonds are more evenly distributed on the working lip. The coated diamond surface is coated with powder, preventing direct contact with the die surface during the pressing process, reducing die wear.

 

With the advent of powder granulation and diamond coating technologies, some domestic companies have introduced foreign-made automatic cold pressing machines for diamond bead production. This equipment uses a volumetric method (fixed powder quantity) to cold-press the base and carcass together, from charging to forming. Its high degree of automation reduces labor, significantly improving production efficiency and reducing costs.

 

2.2 Hot Isostatic Pressing Technology

Sintering diamond beads is a critical step in wire saw production, directly impacting the saw's cutting performance. Beads are cylindrical, thin-walled structures that require high sintering density. Conventional hot pressing sintering methods, due to the thin upper and lower ram walls and poor pressure-bearing capacity, directly limit the sintering density of the beads. Furthermore, they suffer from high ram wear and high costs. The traditional cold pressing followed by pressureless sintering method results in even lower sintering density, significantly impacting wire saw performance. Currently, the most effective sintering method is hot isostatic pressing (HIP). In bead production, the sintered beads are placed in a glass sleeve (some companies omit the glass sleeve and place them directly in a HIP sintering furnace). Then, they are placed in a HIP press, where they are isostatically pressed at 800°C to 900°C using inert Ar gas as the pressure medium. The glass sleeve is then removed by roller blasting or shot peening. Beads produced using this technique have fewer pores and higher density, which improves their hardness, strength, wear resistance, and service life. It also enhances the bond between the base and the matrix. Due to the large furnace chamber, thousands of beads can be loaded at a time, facilitating mass production.

 

 

3.1 Brazing Technology

Impermeable diamond tools are made by mixing diamond particles and metal powder and then sintering them. The diamond particles are generally randomly distributed within the matrix. As the matrix wears during operation, layers of diamond particles emerge, acting as micro-cutting edges to carve the material. These particles then wear, break, and fall off, working in a relay cycle until the tool is completely consumed. The diamonds in impregnated, sintered beads are randomly distributed within the matrix, resulting in uneven spacing between the abrasive particles. The matrix primarily relies on mechanical force to hold the diamonds in place, resulting in low edge value, low cutting efficiency, and difficulty in self-sharpening. This prevents each diamond from fully utilizing its grinding function, leading to waste of raw materials. The principle of diamond bead brazing involves using a brazing filler metal containing active elements (such as Ti, Cr, and W). During the brazing process, the active elements chemically react with the diamond surface, forming a carbide layer. This carbide layer creates a strong chemical metallurgical bond between the diamond, the matrix (braze filler metal), and the substrate. Domestic brazing beads primarily use nickel- or titanium-based fillers, then are sintered under vacuum or an argon atmosphere. Currently, domestic companies primarily produce single-layer diamond brazing beads; multi-layer diamond brazing beads remain under research.

 

 

3.2 Diamond Directed Arrangement Technology

Diamonds are arranged in an orderly pattern on the tool working lip. The spacing and pattern between diamonds are controllable to meet the cutting requirements of different cutting targets. This technology is called diamond directed arrangement technology. Methods for achieving ordered diamond arrangement include templates, dispensing, and lasers. The latest practical method involves forming the required regularly spaced holes during the cold-pressing process. The hole diameter is designed based on the coarsest diamond coating particle size. This process is then performed automatically using an automated cold-pressing machine. Diamonds are then inserted into the holes using specialized equipment, followed by cold pressing and hot-pressing sintering. With the diamonds arranged orderly on the working lip of the bead, cutting efficiency and cutting life are significantly improved compared to traditional beading, significantly increasing diamond utilization.

 

3.3 Integrated Technology Application

In summary, beads produced using the integrated manufacturing technology of high-temperature brazing and orderly diamond arrangement offer significant advantages over impregnation sintering and electroplating, particularly for applications in small-diameter beaded ropes.

 

Its main advantages are:

• ① High diamond exposure. While the diamond tip height of conventional beads is limited to 1/3 of the abrasive grain height, brazed beads can reach up to 2/3 of this height. With a diamond exposure height of up to 70% to 80%, this significantly expands the chip space and reduces the risk of chip blockage and tool failure.
• ② High cutting efficiency. Brazed beads offer four times the cutting efficiency of conventional sintered beads. Their strong chemical metallurgical bond is ideal for efficient grinding.
• ③ High diamond utilization: Diamond usage is reduced by half, reducing costs while maintaining a sawing life equivalent to that of conventional beads. Brazing technology is particularly effective for small-diameter beads. Reducing the diameter of the matrix of impregnated sintered beads loses their multi-layered diamond characteristics. However, brazing technology enables the production of diamond beads with superior performance in smaller sizes.

 

 

 

4.1 New Series of Diamond Wire Saws

Compared to the traditional series of diamond wire saws (typically with diameters of 58-512mm), a new series of diamond wire saws has emerged, exemplified by the use of smaller diameter diamond wire saws (typically with bead diameters of 55.5-57.5mm). These are primarily used in applications requiring stringent kerf sizes.

 

The reduction in bead diameter is also crucial for cutting precious stone. The use of smaller diameter diamond wire saws in stone processing not only conserves stone resources but also reduces processing energy consumption, resulting in a more environmentally friendly process. To meet market demand, some domestic companies now produce bead wires in a variety of sizes, with the smallest diameter reaching 56.0mm. Reducing wire saw specifications necessarily requires reducing the diameters of the wire core and diamond beads. The wire rope used is typically only 53.5-53.8mm in diameter. Due to reduced cutting resistance, small-diameter diamond wire saws can cut large areas (4m²) and very thin granite slabs (5mm thick), increasing sawing efficiency by three times. The cutting force and energy consumption of small-diameter wire saws are approximately 20%-30% lower than those of 59mm wire saws, and the cutting time per square meter is reduced by approximately 25%. The dimensional deviation of materials processed using small-diameter wire saws is also smaller than that of large-diameter diamond wire saws, resulting in special properties. Currently, small-diameter beads are best produced using hot isostatic pressing (cold pressing followed by hot isostatic pressing and sintering) or brazing diamond. Reducing the diameter of diamond beads improves productivity and reduces production costs, while also resulting in lower noise, less pollution, and lower energy consumption.

 

4.2 New Applications of Wire Saws for Reinforced Concrete Cutting

Reinforced concrete wire saw technology has reached a relatively mature stage in China, and its practical application is continuously expanding. In addition to traditional reinforced concrete structure cutting, it has also seen widespread application in submarine cable cutting, oil pipeline cutting, large steel and other metal structural components, and boiler and smelting furnace renovation. For example, the submarine oil pipeline and cable conduit cutting wire saw and supporting equipment developed in collaboration between Harbin Engineering University and a domestic company have already been adopted on a small scale. Diamond wire saws have also been extensively used in smelting furnace renovation projects at large and medium-sized domestic steel companies, such as Shanghai Baosteel and Guangxi Liuzhou Iron and Steel. Their advantages, such as small kerfs, simple operation, environmental friendliness, and strong component cutting capabilities, have significantly reduced renovation costs for these companies.

 

 

 

 

Compared to other diamond tools, diamond wire saws are more flexible. They can be used to cut not only straight plates but also irregularly shaped plates. They are not restricted by surface shape, require a simple workspace, and can cut large areas. Using diamond wire saws can improve resource utilization and reduce environmental pollution. These advantages have led to a growing market and a wider range of applications. Technological advances have significantly increased the production efficiency of diamond wire saws through the use of powder granulation and automatic cold pressing. Diamond wire saws manufactured using new processes and methods, such as hot isostatic pressing, diamond directional placement, and brazing, can significantly enhance their overall performance. The widespread use of high-performance diamond wire saws is crucial for improving the utilization of stone resources, reducing cutting costs per unit area, and protecting the ecological environment.

 

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