What is a Diamond Blade?

There are many different types of diamond cutting / drilling tools, such as circular blades, drills and grinding wheels, with each tool having it's own unique uses. They all however keep the same basic principles:

1. A layer of sheet or solid steel.
2. A diamond-impregnated segment.

A diamond-impregnated segment may have three different forms, a segmented rim, a continuous rim or a castellated rim.

The metal centre of the segmented blade is produced from very high quality quenched, drawn steel, with the segments separated by slots. These slots assist in cooling the blade during sawing by allowing water (wet cutting) or air (dry cutting) to flow between the segments. They also permit a certain amount of elasticity in the blade during sawing.

Most of the steel sheet is mill-tensioned so that the blade rotates vertically straight whilst allowing it a certain elasticity.

The segments or diamond-impregnated rims are a mixture of diamond grains and powdered metal. The diamonds used in the manufacture of the saw blades are almost exclusively industrial diamonds of different sizes and qualities depending on the material to be cut. During the manufacturing process the metallic powder and diamond grain mixture is compressed at very high temperature to obtain a solid metal alloy (called the bond or matrix) which retains the diamond grain.

The segment or rim is slightly wider than the steel centre of the blade. This clearance enables the leading edge to penetrate the material without engaging the steel.

Various processes are used for fixing the segments or rims firmly to the steel:

1. Brazing: silver brazing solder is placed between the segment and the steel. The solder melts at high temperature and binds the two elements together. The same applies to drill bits and surface-grinding wheels.
2. Laser Welding: laser microfusion enables the segment to be welded to the steel, to the drill-bit or to the body of the grinding wheel. The laser welded bond is so powerful that it enables the tool to be used for dry cutting.
3. Sintering: some metal bonding materials may be fixed to steel core by sintering. The forces of cohesion are so powerful that they bond the continuous rim to the steel.

How does a diamond blade work?

A diamond saw blade does not cut but works by milling. When the tool is given its edge in the factory, the individual diamond crystals are exposed on the leading edge and the sides of the segment or rim. It is these exposed diamonds which carry out the milling.

The metal matrix holds each diamond in place. Whilst working, each diamond is shouldered at the back by a "comet's tail" which reinforces the supporting action of the bond.

Whilst the blade is rotating on the saw shaft, the operator pushes the blade into the material. The surface diamonds thus exposed mill a groove in the material, reducing it to fine powder. Whilst the blade mills the material, the latter exerts wear on the blade.

During cutting the exposed diamonds may crack or break (all the more rapidly, the harder and denser the material). The material simultaneously starts to abrade the metal matrix, which gradually releases more diamonds. The more abrasive the material, the more rapid the tendency to wear down the matrix.

With a diamond tool properly matched to the material being cut, the equilibrium between the work of the diamond and the resistance of the bond to abrasion is at its optimum: the diamond is held in place until it is destroyed and new crystals appear. The whole quality of a diamond tool resides in this equilibrium.

Blades intended for cutting hard, dense less abrasive materials (such as tiling, hard bricks, stone or old hard concrete), require a softer metal matrix. This will wear down faster, replacing the worn diamonds fairly quickly so that the blade continues to cut.

Blades intended for cutting soft, abrasive materials (like green concrete and asphalt) must have a hard, abrasion-resistant metal matrix in order to retain the diamonds for a greater length of time.

How to select a diamond tool

1. The Price: Decide which is most important to you: the initial price of the tool or the cost per cut. For small jobs, or occasional use, a low-priced tool may be preferable. For larger jobs or regular use, a higher-priced tool will actually be less expensive to use because it will deliver a lower cost per cut. For really big jobs, the lowest possible sawing cost (cost per metre) is usually much more important than the initial price.
2. Wet or Dry Cutting: Choosing wet or dry may be a matter of user preference or job requirement. The use of water requires certain precautions to be taken if electrical equipment is to be used. For concrete floor saws, wet cutting is usually preferred because you can cut deeper when using water as a coolant. For tile and masonry saws, either wet or dry cutting tools can be used. For high-speed cut-off saws, dry tools are more popular, but they are often used wet to control dust. Wet tools and bits MUST be used with water. Dry cutting tools may be used either dry or wet, as the job or equipment allows.
3. The Material to be Cut: Correctly identifying the material you are going to cut is the most important factor in choosing a tool. It directly affects the cutting speed and the life of the tool. You will find diamond tool application recommendations throughout the catalogue to help you select the correct tool for the job. Most tools cut a range of materials. For maximum performance (cutting speed AND life), the tool specification must be matched as closely as possible to the material which will be cut most often, or the material for which top tool performance is most important.
4. Additional Useful Information: The diamond segment height: Diamond tool segment height by itself is not a true measure of a tool's value. Many other factors also affect the performance of the tool; you should also consider the diamond size, concentration and quality, the hardness of the bond, the cutting power (torque) of the equipment; the segment and slot geometry of the steel centre, and how well the blade specification is matched to the material being cut.
5. Which type of rim to choose: A continuous smooth rim provides the smoothest cut in ceramic tiles and ornamental stone. Continuous castellated rim blades or super-jointed segments may produce slight chipping but generally have a longer life and lower cost per cut than continuous rim blades. Segmented blades provide the longest life and lowest cost per cut but are only suitable for work where chipping is not a problem.