Your Guide in Understanding Diamond Saw Blades
In rock and gem cutting, you need something to... well, cut ‒ your material. And while you can use other methods to break your rough rock (e.g., rock hammering, throwing it to shatter into smaller pieces, etc.), cutting it precisely with a saw is the best method, both for precious and semi-precious rock. It reduces the "waste" that you get when shattering the rough. When cutting rock, especially the more valuable ones, we don't want to waste any of the material if we can help it.
Diamond blades are the blades used in lapidary saws. They are preferred to regular saw blades because they are designed to cut denser and harder materials. Diamond saw blades have diamonds evenly embedded into a metal matrix that makes up the rim, which cuts directly through the material.
If you're wondering whether "diamond blades" have real diamonds, the answer is no. The diamonds used in these blades are synthetic diamonds, also known as lab-grown diamonds. They are created by scientists in a laboratory by growing a small diamond seed in layers through high pressure and temperature.
Although these diamonds are synthetic, their physical and chemical properties are the same as natural diamonds. Thus, their hardness is no different and they can still cut through most hard materials.
Types of Diamond Blades
In lapidary, there are three common types of diamond blades. Those are sintered rim, segmented rim, and notched rim blades.
A sintered diamond blade is a continuous rim blade, where diamonds are embedded in the metal alloy. If ever the metal bond wears out, new diamonds will be exposed and the blade will continue cutting. This is a thin blade and is perfect for cutting precious gemstones and soft materials, because of it having less kerf and the clean-cut it gives.
Segmented rim blade has wide and deep gullets to allow the coolant to flush the dust and cool the blade. This is a versatile blade. It can cut precious and semi-precious rock precisely.
Notched rim blades are a production blade that can withstand demanding usage. It has small notches where segments are inserted and pressed to form the rim. This has the longest life, hence it is popular in industrial lapidary.
Wet or dry cutting?
In certain instances, like using other kinds of diamond blades in construction, or when cutting softer materials like asphalt or cement, a diamond blade may cut dry.
However, it is not the case when it comes to cutting rock and gemstones. In lapidary, a saw and a diamond blade can only be used in wet cutting. This is crucial in preventing friction or heating up between the blade and the rock. It will also make the blades last longer.
How do diamond blades work?
Although we say "cutting rock", diamond blades don't actually cut, they grind! The diamonds are supported by the metal matrix, and the exposed bits of diamonds grind a kerf onto the material. A kerf is the width of the material that is removed in grinding.
If the diamond blade keeps on grinding and is used for a long time, the diamond and metal bond will slowly wear out, exposing new diamond bits. This cycle will go on until no diamond is left on the rim. When the diamond is consumed and the blade won't grind anymore, that's the time when you have to replace your blade.
Sizes and Quality of the Diamond
When choosing a diamond blade for rock cutting, you need to consider the size and quality of the diamond. For sizes, the higher the number, the finer the diamond particles and the smaller the number, the coarser the blade will be. If you're cutting hard materials, it's best to use a blade with fine diamond, while coarse particles are used when cutting a softer material.
A good quality diamond is determined by its ability to withstand high temperatures and maintain a sharp point. Some diamond blades in the market are sold really cheap. Those kinds of diamond blades have poor quality and will wear out after only a few uses.
Diamond Blade Maintenance
Aside from using an appropriate high-quality coolant, a diamond blade needs to be sharpened every once in a while to maintain its performance. If your blade stops cutting or isn't producing good cuts, it probably needs resharpening. In most diamond blades, as long as the metal alloy and diamond are present on the rim, a blade can be salvaged by resharpening.
There are various methods of sharpening a blade, as recommended by other lapidarists. Those are cutting through obsidian rock and silicon carbide block. They're both acceptable methods, but the results aren't remarkable.
John Rowland, CEO of Highland Park Lapidary, made a video on how to sharpen a diamond blade, using a bastard file. In his tutorial video, he demonstrated how to pound lightly onto the rim of the blade, to expose the diamonds.
Watch the video here:
Different Types of Diamond Blades
Different Types of Diamond Blades
Which Type of Diamond Blade is Right For You?
Stone, porcelain, concrete, asphalt, and other similar hard materials are no match for diamond blades. Diamond blades don't really "cut" anything—instead, they grind their way through anything they're aimed at, but it seems like they are cutting directly through these objects which is not the case. The blades are made from a durable composite of synthetic diamond particles and powdered metals. This amalgam is then bonded to a solid steel core to create a durable blade ideal for use in the construction industry and home improvement projects.
The Segmented Rim Diamond Blade
The segmented rim, which can be used in numerous dry cutting applications, is also known by the name "dry cutting blade." As the blade has the roughest cut among the three choices, it works best on masonry materials like brick and limestone. The bonding of segmented blades, which can be used for both wet and dry cutting, is normally medium to hard. These blades may provide a fast, generally smooth cut, but chipping is still possible. When compared to other blades, their lifespan is quite long and they are extremely sturdy.
They work optimally for chopping through stone like marble and granite as well as construction materials like asphalt, brick, and block. They come in a wide range of diameters from very small to extremely huge, but their sweet spot is the market for sizes 12 inches and up. Masonry saws, concrete saws, and circular saws all effectively use this blade to cut through the previously mentioned objects.
Gulets refer to the air pockets that form between the individual parts. The gullets are designed to increase airflow, dissipate heat, and evacuate slurry from the cut, all of which contribute to the blade's continued efficiency. Depending on the material the blade is meant to slice through, its gullets will be a specific size and form.
Blades designed for cutting asphalt often have broader U-shaped gullets than those designed for cutting concrete. The hole should be wider for better heat dissipation if the material is more abrasive. The keyhole, teardrop, and angled gullets are some of the others. Diamond segmented blades with narrow slots are typically used for marble and granite, while keyhole-shaped slot blades are more commonly used for general-purpose cutting.
The Turbo Rim Diamond Blade
The turbo rim on this blade makes it the best option for quick cutting in either wet or dry conditions. This blade is specially made for cutting hard materials like tile and natural stone quickly and easily with its serrated edges. The bindings on turbo blades are typically soft to medium, making them suitable for a wide range of general-purpose and specialized cutting tasks. All of a turbo blade's cutting edge is serrated, forming a continuous rim. Combining the greatest features of segmented and continuous rim blades, its serrated edge allows the blade to achieve higher cutting speeds without sacrificing smoothness.
Common diameters for these blades are 4", 8", 10", and 12". They are useful for cutting tile, stone, marble, granite, masonry, and other construction materials when installed in grinders, circular saws, and tile saws. It is possible to get blades designed for dry as well as wet cutting.
Continuous Rim Diamond Blade
The continuous rim blade is well known for optimally cutting with water and is more of a wet application type of diamond blade. This blade is ideal for marble, granite, and porcelain since it cuts slowly and smoothly and leaves the least amount of dust. Since it does not have separated edges, but rather a “continuous” edge that enables it to cut with perfect precision and neatness, is why it is very preferable to the applications it excels at. When cutting tile, porcelain, granite, stone, glass, or other brittle materials, continuous rim blades' gentler bonding is preferable. These blades have a single, continuous edge rather than multiple smaller ones. Wet cutting is ideal for continuous rim blades because it produces the cleanest cuts.
The most frequent diameters for these blades are 4 inches to 14 inches. Hand-held grinders typically use the smaller, 4" to 5" diameter blades, whereas bigger diameters are employed with circular saws and tile saws.
Continuous rim blades come in a number of configurations. In order to boost durability, blade life, and cutting speeds, the J-slot design is one variant that incorporates J-slots along the edge of the blade to aid in heat dissipation. Dry cutting can also be accomplished with J-slot continuous rim blades.
Diamond blade
A diamond blade is a saw blade which has diamonds fixed on its edge for cutting hard or abrasive materials. There are many types of diamond blade, and they have many uses, including cutting stone, concrete, asphalt, bricks, coal balls, glass, and ceramics in the construction industry; cutting semiconductor materials in the semiconductor industry; and cutting gemstones, including diamonds, in the gem industry.
Types
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Diamond blades are available in different shapes:
- Circular diamond saw blades are the most widely used type of diamond blade.
- A diamond gang saw blade is a long steel plate with diamond segments welded onto it. Normally, tens or 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 by electroplating) on one edge of the band.
Diamond blades designed for specific uses include marble, granite, concrete, asphalt, masonry, and gem-cutting blades. General purpose blades are also available.
Manufacturing methods
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Electroplating
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Blades using diamonds embedded in a metal coating, typically of nickel electroplated onto a steel blade base, can be made to be very thin—blades can be tens of micrometres thick, for use in precise cuttings.
Vacuum brazing
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Vacuum brazed diamond saw blades are manufactured by brazing synthetic diamond particles to the outside edge of the circular saw blade in a vacuum brazing furnace. All of the diamond particles are fully exposed and fastened on the exterior cutting edge of the blade instead of being embedded within a metal-diamond mixture. Depending on the manufacturer's recommended blade application, vacuum brazed blades will cut a wide variety of material including concrete, masonry, steel, various irons, plastic, tile, wood and glass.
Finer synthetic diamond grits will reduce the chipping of tile and burring of steel and provide a smoother finish. Larger diamond grits will provide a higher cutting speed, but will be more likely to cause chipping, burring, or cracking. Fire departments sometimes use vacuum brazed saw blades and require blades to be made with a very large diamond grit, to tear through material quickly. An intermediate grit size is used by the production industry.[1]
Sintering
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Sintered metal-bonded diamond blades are the most common type of blade. These blades consist of a steel core (the base is steel plate, unlike that of the wires used in diamond wire saws) and diamond segments, which are made by combining synthetic diamond crystals with metal powder and then sintering them. The diamond segments are also known as the "cutting teeth" of the blade.[2]
The steel core can vary in design. Some cores have spaces (known as gullets) between segments to provide cooling and slurry removal, while others have a single continuous rim for smoother 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 it in a sintering furnace equipment. Consequently, the diameter of wholly sintered diamond blades is not very large, normally not more than 400 millimetres (16 in). Because it is participating in the sintering process, the steel core cannot be quenched, so the hardness and strength of the core are not very high. This means that these types of diamond blade may deform in high-load and high-intensity cutting processes and can exhibit low cutting efficiency.
Silver brazed and laser welded diamond blades do not have this weakness 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, meaning that the blade can be used in high-load and high-intensity cutting processes with high cutting efficiency and a smaller degree of deformation.
Silver brazed diamond blades' diamond segments are brazed to the steel core using a silver solder. These blades can only be used in wet cuttings. If they are used in dry cuttings, the silver solder may melt and the segments can break from the steel core and become a serious safety hazard. A 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, meaning that 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 possible for the diamond segment itself to break or the steel core below the segment to wear and break, creating serious safety hazards.
Application of sintered metal-bonded diamond blades
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A diamond blade grinds, rather than cuts, through material. Blades 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 bond to the 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. 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.[clarification needed] 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 diamonds should be smaller.
There are other factors that should be considered when choosing a diamond blade for a particular application. These include the type (manufacturing method) of the blade, the availability of water in the cutting process, the horsepower of the saw, and the acceptable level of noise created by the saw. For example, if the horsepower of a saw machine is large, the diamond concentration of the diamond blade should be higher, or the bond should be harder. Higher diamond concentration will decrease the impact on each single diamond in working, while a harder bond will hold the diamonds more firmly.
Cutting with or without water
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Many blades are designed to operate either wet or dry. However, diamond tools and blades work better when wet, and dry cutting should be limited to situations in which water cannot or should not be used. Water will prevent the blade from overheating, greatly reduce the amount of harmful dust created by cutting, remove the slurry from the cut, and extend the life of the blade, since diamond is unable to withstand the forces involved at the elevated temperatures involved in dry cutting ceramic and abrasive materials, and will be subject to rapid tool wear and possible failure.
When water cannot be used (in, for example, electrical saws), measures should be taken to ensure that the operator does not inhale the dust created by the process, which can cause silicosis, a serious lung disease. When 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. The OSHA has strict regulations regarding silica dust and requires a N95 NIOSH-approved respirator in work sites where dangerous amounts of silica dust are present.[3][4]
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