Summary and analysis of the service life of diamond saw blades

Diamond saw blades are indispensable tools in stone mining and processing.

Their efficiency and service life are determined by many factors, which can be summarized and analyzed to include the following parameters:

 

 

 

• (1) Saw Blade Linear Speed: In practical work, the linear speed of a diamond circular saw blade is limited by equipment conditions, saw blade quality, and the properties of the stone being sawed. For optimal saw blade service life and sawing efficiency, the linear speed should be selected according to the properties of different stones. When sawing granite, the saw blade linear speed can be selected within the range of 25m~35m/s. For granite with high quartz content that is difficult to saw, the lower limit of the saw blade linear speed is preferable. When producing granite tiles, the diameter of the diamond circular saw blade used is relatively small, and the linear speed can reach 35m/s.
• (2) Sawing Depth: Sawing depth is an important parameter involving diamond wear, effective sawing, saw blade stress, and the properties of the stone being sawed. Generally speaking, when the linear speed of a diamond circular saw blade is high, a small cutting depth should be selected. Currently, the cutting depth for diamond cutting can be chosen between 1mm and 10mm. When sawing granite blocks with a large-diameter saw blade, the cutting depth can usually be controlled between 1mm and 2mm, and the feed rate should be reduced. When the linear speed of the diamond circular saw blade is large, a large cutting depth should be selected. However, within the permissible range of saw machine performance and tool strength, a larger cutting density should be used to improve cutting efficiency. When there are requirements for the machined surface, a small depth of cut should be used.
• (3) Feed rate: The feed rate is the feed speed of the stone being sawed. Its magnitude affects the sawing rate, the force on the saw blade, and the heat dissipation in the sawing zone. Its value should be selected based on the properties of the stone being sawed. Generally speaking, when sawing softer stones, such as marble, the feed rate can be appropriately increased. If the feed rate is too low, it is more conducive to improving the sawing rate. For sawing fine-grained, relatively homogeneous granite, the feed rate can be appropriately increased. If the feed rate is too low, the diamond cutting edge is easily worn down. However, when sawing coarse-grained granite with uneven hardness, the feed rate should be reduced; otherwise, the saw blade will vibrate, causing the diamond to break and reducing the sawing rate. The feed rate for sawing granite is generally selected within the range of 9m~12m/min.

 

 

 

 

• (1) Diamond grit size: Commonly used diamond grit sizes are in the range of 30/35~60/80. The harder the rock, the finer the grit size should be selected. This is because under the same pressure conditions, the finer the diamond, the sharper it is, which is beneficial for cutting into hard rocks. In addition, large-diameter saw blades generally require high cutting efficiency and should be selected with coarser grit, such as 30/40 or 40/50; small-diameter saw blades have low cutting efficiency and require smooth rock cuts, so they should be selected with finer grit, such as 50/60 or 60/80.
• (2) Diamond concentration: Diamond concentration refers to the density of diamonds distributed in the working matrix (i.e., the weight of diamonds per unit area). The "Specification" stipulates that when there are 4.4 carats of diamonds per cubic centimeter of working matrix, the concentration is 100%, and when there are 3.3 carats of diamonds, the concentration is 75%. Volume concentration indicates the volume occupied by diamonds in the agglomerate, and it is stipulated that when the volume of diamonds occupies 1/4 of the total volume, the concentration is 100%. Increasing the diamond concentration can extend the life of the saw blade because increasing the concentration reduces the average cutting force on each diamond. However, increasing the cutting depth inevitably increases the cost of the saw blade. Therefore, there exists an optimal concentration, which increases with the cutting rate.
• (3) Hardness of the bonding agent: Generally, the higher the hardness of the bonding agent, the stronger its wear resistance. Therefore, when sawing highly abrasive rocks, a high bonding agent hardness is preferable; when sawing soft rocks, a low bonding agent hardness is preferable; and when sawing highly abrasive and hard rocks, a moderate bonding agent hardness is preferable.
• (4) Force effect, temperature effect, and wear: During the cutting process of stone, diamond circular saw blades are subjected to alternating loads such as centrifugal force, sawing force, and sawing heat.

 

Wearing damage of diamond circular saw blades is caused by force and temperature effects.

a,Force effect:

• During the sawing process, the saw blade is subjected to axial and tangential forces. Due to the forces acting in the circumferential and radial directions, the saw blade is wavy in the axial direction and disc-shaped in the radial direction. Both of these deformations result in uneven rock cuts, increased stone waste, higher noise levels during sawing, and intensified vibration, leading to premature diamond agglomeration failure and reduced saw blade life.

 

b, Temperature Effect:

• Traditional theory suggests that temperature affects the saw blade process primarily in two ways: firstly, it causes graphitization of diamond within the agglomerates; secondly, it creates thermal stress between the diamond and the matrix, causing premature diamond particle detachment. New research indicates that the heat generated during cutting is mainly transferred to the agglomerates. The arc zone temperature is not high, generally between 40 and 120°C. However, the abrasive grinding point temperature is much higher, generally between 250 and 700°C. The coolant only lowers the average temperature of the arc zone, having little effect on the abrasive temperature. Such temperatures do not cause graphite carbonization, but they alter the frictional properties between the abrasive and the workpiece, and create thermal stress between the diamond and the additives, fundamentally altering the diamond failure mechanism. Research shows that the temperature effect is the most significant factor influencing saw blade breakage.

 

c, Wear and tear:

• Due to force effects and temperature variations, saw blades often experience wear and tear after a period of use. The main forms of wear and tear include: abrasive wear, localized breakage, large-area breakage, detachment, and mechanical abrasion of the binder along the sawing speed direction. Abrasive wear: Continuous friction between diamond particles and the workpiece dulls the edges, reducing their cutting performance and increasing friction. The heat from sawing causes a graphitized thin layer to form on the surface of the diamond particles, significantly reducing hardness and exacerbating wear. The diamond particle surface is subjected to alternating thermal stress and alternating cutting stress, leading to fatigue cracks and localized breakage, revealing sharp new edges – a more ideal wear pattern. Large-area breakage: Diamond particles are subjected to impact loads during entry and exit, causing prominent particles and grains to be consumed prematurely. Detachment: Alternating cutting forces cause the diamond particles to be constantly shaken within the binder, resulting in loosening. Simultaneously, the wear of the binder itself and the heat from sawing soften the binder. This reduces the holding force of the binder, and when the cutting force on the particles exceeds the holding force, the diamond particles will fall off. Both types of wear are closely related to the load and temperature experienced by the diamond particles. Both of these depend on the cutting process and cooling/lubrication conditions.