Many in the concrete construction industry believe that a diamond saw blade is just a diamond saw blade. There are, however, many different types of diamond saw blades that when properly used can maximize cutting tool performance. Diamond plays an important role, but the operator must look at many other factors to optimize saw blade performance and troubleshoot any problems that arise.
HOW DIAMOND TOOLS WORK
A diamond saw blade is a circular steel disk with segments attached to the outer perimeter of the blade. Each segment holds in place a specially formulated mixture of metal bond powders and diamond, pressed and heated in a sintering press by the manufacturer. The diamond and bond are tailor-made to the specific cutting application. There are, however, many factors to consider prior to cutting.
BLADE OPERATING SPEEDS
Manufacturers produce blades for specific applications. They recommend operating speeds or a maximum operating speed and print this information directly on each blade. Recommended operating speeds are based on blade size, equipment type, and the material being cut. Maximum operating speeds are set by the American National Standards Institute (ANSI) Code B7.1. Never operate a blade above the maximum or "Do Not Exceed" revolutions per minute (rpm) stamped on the blade. Failure to comply with this warning is dangerous and can result in injury or death.
The best operating speeds for cutting concrete are around 10,000 surface feet per minute (sfpm) or the surface speed of the diamond cutting segments on the periphery of the blade. This operating limit has been established as an optimum speed for cutting concrete. The diamond blade operating speeds provide operators with recommended operating speeds and maximum safe speeds for a range of blade diameters. Attaching a tachometer to the machine's blade shaft can check machine speeds so the rpm can be adjusted in the field for operating blades of different diameters.
It is important for the operator to use the correct operating conditions to maximize blade performance. For optimum blade life and cutting speed, the actual operating speed most likely will have to be adjusted for the aggregate type and the amount of steel encountered. In general, higher operating speeds make the blade act harder and tend to lengthen blade life but slow the cutting. Decreasing blade speed will make the blade act softer, but blade life also will decrease.
If there is any doubt, it is better to choose a lower speed rather than a higher speed. Once the blade is cutting well, the speed can be increased to optimize life of the diamond blade. If softer abrasive materials are being cut at faster peripheral speeds, a faster forward traverse rate and more water should be used.
DEPTH OF CUT
The depth of cut should be adjusted so that a forward saw speed of 8 to 10 feet per minute (fpm) can be maintained while cutting concrete. Water or some other coolant must be used to cool most diamond blades. If not enough water is used, the swarf will not be removed from the cut quickly. This is a common, but not the main cause, of undercutting where the abrasive particles from the cut wear away the steel core just below where the diamond segment is attached to the steel core. Without sufficient water, the core will also overheat, causing cracks and premature loss of segments. To minimize blade wear, an adequate volume of water is essential. The water flow for cooling saw blades should be between 1.3 and 2.6 gallons per minute. The operator should check the depth of cut with a ruler.