A diamond blade is a saw blade which has diamonds fixed on the blade's base to use the diamonds to cut hard or abrasive materials. There are many types of diamond blades, and they have been applied in many industries, for example, construction industry to cut stone, concrete, asphalt, bricks, coal balls, glass and ceramics, IT industry to cut semiconductor materials, and gem industry to cut gem stones including diamonds.
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Diamond blades can be categorized by their shape, use, and manufacturing method.
If categorized by their style, diamond blades are available in different types: circular saw blades, gang saw blades and band saw blades.
Circular diamond saw blades are commonly sighted and the most widely used. Most diamond blades are of this style.
A diamond gang saw blade is a long steel plate with diamond segments welded on it. Normally, a group (tens or even hundreds) of diamond gang saw blades are used together to saw raw stone blocks.
A diamond band saw blade is a flexible closed steel band with diamonds fixed (often via the electroplating method) on the teeth of one side of the band.
If categorized by use, there are marble diamond blades, granite diamond blades, concrete diamond blades, asphalt diamond blades, general purpose diamond blades, masonry diamond blades, gem cutting diamond blades, etc.
There are many methods to attach diamonds onto the saw blade's base . A common method is sintering the mixture of diamonds and metal powders are formed to the blade's cutting edges—diamond segments, and the produced diamond blades can be called sintered metal-bonded diamond blades.[1] Other methods include electroplating, vacuum brazing, extruding and so on.
Diamonds are electroplated onto the metal blade base. Electroplated diamond blades can be made to be very thin. The thickness of the blade can be tens of microns and can be used in precise cuttings.
Synthetic diamond particles are welded to the outside edge of the circular saw blade via a vacuum brazing furnace. All of the diamond particles are on the exterior cutting edge of the blade, with no metal/diamond mixture. When using a vacuum brazed diamond blade you need not match the type of blade with the material being cut. Depending on the manufacturers recommended blade application, vacuum brazed blades will cut a wide variety of material ranging from concrete to masonry, materials like stone and brick, to steel, various irons, even plastic, tile, wood & glass. Always consult your blade manufacturer for a full list of cutting applications.
Smaller finer synthetic diamond grits will provide a smoother finish with no chipping on tile or burring on steel. Larger diamond grits will provide a faster cutting speed, but will likely cause chipping, burring or cracking of your material. Fire departments require blades to be made with a very large diamond grit, to tear through material fast, while a happy medium is required for the production industry.[2]
Sintered metal-bonded diamond blades are the most common type. A blade of this type is composed of a steel core (the blade's base is steel plate, unlike diamond wire) and diamond segments which are made by combining synthetic diamond crystals with powder metal and then sintering them. The diamond segments are also known as the "cutting teeth" of the blade.[3]
The steel core can vary in design. Some of them have spaces (known as gullets) between each segment to provide cooling and slurry removal, while others have a single continuous rim for smoother chip-free cutting. The type of core that can be used depends on the type of materials that the diamond blade is designed to cut.
Generally, there are three types of sintered metal-bonded diamond blades according to their manufacturing methods: wholly sintered diamond blades, silver brazed diamond blades and laser welded diamond blades.
A wholly sintered diamond blade is made by putting the steel core together with the diamonds and the metal bond materials into a mold and then sintering them in a sintering machine. So the diameter of wholly sintered diamond blades is not very big and normally is not bigger than 400 millimetres (16 in). Also because its participating in the sintering process, the steel core cannot be quenched, so the hardness and strength of the core is not very high, these types of diamond blades may deform in high-load and high-intensity cutting processes. Therefore, in some cases wholly sinter diamond blades' cutting efficiency cannot be very high.[1]
Silver brazed diamond blades and laser welded diamond blades, however, do not have this problem. Because their diamond segments and steel core are treated separately. The steel core can be quenched and processed with other heat treatments, so its hardness and strength can be high, therefore the blade can be used in high-load and high-intensity cutting processes without deformation and high cutting efficiency can be gained.[1]
Silver brazed diamond blades' diamond segments are brazed to the steel core using a silver solder. Silver brazed diamond blades can only be used in wet cuttings. Because if they are used in dry cuttings, the silver solder may melt under the high temperature generated in the dry cutting and the segments can break from the steel core and be extremely dangerous. While the laser melts and combines the metal of the diamond segment and the steel core creating a stronger weld, which can hold the segments even in high temperatures, so laser welded diamond blades can be used to cut many types of stone without water cooling. However, when cutting very hard or abrasive materials, e.g., concrete containing reinforcing rebar, laser welded diamond blades should also be used with adequate water. Otherwise, it is fairly possible that the diamond segment itself breaks or the steel core below the segment wears and breaks, and then causes serious security issues.[1]
A diamond blade does not actually cut. Instead, it grinds. They typically have rectangular teeth (segments) which contain diamond crystals embedded throughout the segment for grinding through very hard materials.
The bond is a term used for the softness or hardness of the powder metal being used to form the segments. The powdered metals hold the diamonds in place. The bond controls the rate at which the diamond segments wear down allowing new diamonds to become exposed at the surface to continue grinding with a "sharp" edge. An important step in choosing a blade is to match the right bond to your specific material to be cut. Additional factors to consider are the type and power of the equipment to be used and the availability of water. The hardness of the bond is inversely related to the hardness of the material to be cut. Harder materials need a softer bonded segment to allow for continuous diamond exposure. Softer materials like asphalt or freshly poured concrete can use a harder segment to resist the increased wear that softer, abrasive materials create. In addition, the diamonds' grit (size), toughness and concentration should also match the nature of the material to be sawed. For example, when hard materials are cut, the size of the diamonds should be smaller, because smaller diamonds are more easily to cut into hard materials.[4]
Apart from the nature of the material to be sawed, there are also some other important aspects that should be considered when you are choosing a diamond blade for your application. These aspects include the type (manufacturing method) of the blade, the availability of water in the cutting process, the horsepower of your saw machine, whether you need the blade to make lower noise, and so on. For example, if the horsepower of your saw machine is big, the diamond concentration of the diamond blade should be higher, or its bond should be harder. Because when the diamond saw blade is used on a big-powered saw machine, the diamonds on the blade will receive bigger impact. Higher diamond concentration will decrease the impact on each single diamond in working. Harder bond can hold the diamonds more firmly.[5]
Diamond tools and blades work best when cutting wet. The water will prevent the blade from overheating, greatly reduce the amount of harmful dust created by cutting, and will remove the slurry from the cut. Diamond cannot withstand the forces involved at the elevated temperatures of dry cutting ceramic and abrasive materials, and will be subject to rapid tool wear and possible failure. Blade life is greatly extended by wet cutting. However, many blades are designed to operate either wet or dry. Dry cutting should be limited to situations where water isn't readily available.
When water cannot be used (electrical saws for example), measures should be taken so the operator does not inhale dust created by the process, which poses a very serious health risk known as Silicosis. When doing dry cutting, the blade should be allowed to cool off periodically. Cooling can be increased by allowing the blade to spin freely out of the cut. This allows cool air to pass between the segments. Dry diamond cutting is dangerous for persons unfamiliar with the risks and process. OSHA has strict regulations regarding silica dust and requires a N95 NIOSH-approved respirator in work sites with silica dust.[6][7][8]
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