Some Concrete construction workers in the industry believe that a diamond saw blade is just a diamond saw blade. However, there are 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 BLADES 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.
- 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.
- Operating conditions to maximize blade performance, 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.
MATERIAL TO BE CUT
Knowing as much as possible about the concrete can be of enormous benefit to the cutting operator and the tool manufacturer. To recommend a blade, a manufacturer must know the type of aggregate to be cut and if rebar will be present. Limestone or coral aggregates are relatively soft and abrasive, providing little problem for the diamond blade to cut. Concrete with river gravel or quartzite aggregate is of medium difficulty to cut. Flint or granite aggregate generally is considered among the most difficult to cut.
Aggregate size also can affect the cutting performance of a diamond blade. Concrete aggregates often range from 1/2 inch to 2 inches. Concrete made with 2-inch flint aggregate will be extremely difficult to cut, but concrete with 1/2-inch flint aggregate may be cut more easily. This is because there is more coarse aggregate per unit volume of concrete than when a larger, maximum-size aggregate is used.
The type of aggregate has a pronounced effect on blade wear, and hence life. Hard aggregates shorten blade life and slow the cutting rate so cutting concrete with a hard aggregate will cost much more than cutting concrete with a soft aggregate. Cutting concrete made with hard aggregates also requires more power. If there is not enough power, bit speed or blade speed should be reduced.
They are ideal for cutting marble and granite slabs, concrete, asphalt, brick, block, and other building materials. They are available in a wide selection of diameters from small to large and particularly dominate the 12” diameter and larger market. These diamond segmented blades are commonly used with masonry saws, concrete saws, and circular saws.
The spaces of air that separate the diamond segments are called gullets or slots. The slots are there to improve air flow, cutting materials dust, dissipate heat, and remove slurry from the cut, helping to maintain the saw blades cutting performance. The size and shape of the gullets vary from blade to blade and will depend on the type of material the blade designed to cut.
For example, blades for cutting asphalt tend to have wider, U-shaped slots while diamond saw blades for concrete tend to have narrower U-shaped slots or Keyhole slot. The more abrasive the material, the wider the slot should be to allow for better heat dissipation. Other slots shapes include teardrop and angled. Segmented diamond saw blades with narrow slots are generally for marble and granite while keyhole shaped slot blades tend to be for general purpose.
Diamond continuous rim blades have softer bonds for cutting hard materials such as tile, porcelain, granite, ceramic, glass, and other materials that can chip easily. These diamond saw blades don’t have individual segments but instead have a solid, continuous rim or edge. Most diamond continuous rim blades are designed for wet cutting applications, providing the smoothest, chip free cuts.