Understanding Diamond Blades

Vacuum Brazed or Sintered Attachment

The process level used to manufacture the core is related to the attachment methods. Lower cost, higher volume blades use either a vacuum brazed or sintered attachment process. Vacuum brazed and sintered blades are intended for dry cutting soft material on low horsepower equipment. The cores used for these blades are typically very simple and do not undergo many of the steps of the blades for more aggressive applications.

Laser Welded Attachment

Of the three most common forms of attaching the segments to the core, and by far the method that yields the strongest bond to the core, is laser welding. As the pioneer in laser welding, Norton continues to develop and perfect laser welding techniques. The more aggressive applications for diamond blades involve the use of higher horsepower equipment wet cutting harder materials to much greater cut depths. The steel cores for these aggressive applications are thicker, heat-treated, precision-ground, and tensioned. The additional thickness and heat treatment allows the core to withstand the flexing stress of the heavier equipment and higher horsepower. The precision grind on the surface minimizes the drag while the tensioning establishes the flatness of the blade at a specific rpm range.

a. Diamond Crystals (Cut)

The diamond used is manufactured or synthetic as opposed to natural. Manufactured diamond is preferred over natural diamond because key characteristics like crystal shape, size, and strength can be closely controlled through the manufacturing process. The ability to control the key characteristics of the synthetic diamond allow for accurate prediction of cutting speed and blade life as well as consistent repeatability. Some other important factors to consider about diamond are the:

•    amount of diamond in the segment

•    quality of the diamond in the segment

•    size of the diamond in the segment  

Amount of Diamond:

The amount of diamond in the segment is variable and requires more horsepower as the content of diamond is increased in the segment. Simply put it means that as more diamond is added to the segment more horsepower is needed to make the blade cut. In practical terms this means that blades for high horsepower saws will have more diamond in the segment.

Quality of the Diamond:

The quality of the diamond determines the ability of the individual diamond to resist heat and maintain a sharp point. Better diamonds can hold a point longer at higher temperatures.  

Size of the Diamond:

Finally the last thing to consider is the size of the diamond. The individual’s diamond sizes are specified in mesh ranges like 25-35 or 50-60. The higher the numbers the finer the individual particles. In practical application finer diamond is used for critically-hard material like Chert or Quartz while the larger more coarse diamond is used for soft materials like asphalt and soft red clay bricks.

b. Bonding System (Wears)

The bond is a mixture of metal powders used in various combinations to achieve specific wear rates. A correctly-formulated bond holds the diamond in place, just long enough to get maximum use from the diamond points before releasing the stone and exposing the next layer of diamond.  

The wear rate for the segment can be simplified to the ability of a metal to resist wear from abrasion. Metals with low abrasion resistance like bronze are considered soft. The soft bonds are mostly made up of soft metals like Bronze and are common when cutting very hard less abrasive material like porcelain. The hard bonds are mostly made up of hard metals like Tungsten Carbide and are common when cutting very soft abrasive materials like asphalt or freshly poured concrete.  

The best way to remember bond-to-material application is “opposites attract” - hard bonds for soft abrasive materials while soft bonds are used for hard less abrasive materials. In some extreme cases, it is possible to simply judge the hardness of the blade by noticing the color of the segment. Because soft blades contain a majority of Bronze, the soft blades for extremely hard materials will have a yellow tint to the segment.

Diamond blades don't cut, they grind!  The exposed diamond crystals do the grinding work. The metal matrix or bond holds the diamonds in place. Trailing behind each exposed diamond is a “bond tail” which helps to support the diamond. As the blade rotates through the material the exposed surface of the diamonds grind the material being cut into a fine powder.

After several thousand passes through the material being cut, the exposed diamonds begin to crack and fracture. The matrix holding the diamond also begins to wear away.

Eventually the diamond completely breaks up and its fragments are swept away with the material that it is grinding.

As the diamond wears and fractures, controlled erosion of the metal bond containing the diamond exposes new sharp diamond points. This cycle of erosion and exposure continues until all of the diamond and metal bond section of the segment is gone. Once the cutting section is consumed the blade will no longer grind letting the operator know it is time for a new blade.