I first got involved with diamond blades in 1981 at my Father’s Rental Store. Norton had just introduced laser welding technology which allowed a blade to be run dry. Prior to that, most diamond blades were silver soldered (brazed) and abrasive blades ruled the market. If I remember correctly, the cost of a 14” diamond blade was over $400 and the applications were very specialized. We attempted to rent this expensive blade but time after time the users came back with problems.
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Diamond blades were built back then to be used only in specific applications. If there were slight differences in aggregate or hardness, we would need to use a different bond structure. More often than not, the operator did not know the true specifics of the application, and the rental resulted in failure. While just a teenager, I was determined to find a way to make this product work for our company and decided to learn everything I could about diamond blades.
Needless to say, the industry has changed dramatically since then. The bond structure used today is much more forgiving, and costs have dropped as much as 90% over the last thirty years. The lower cost has opened the market to a much larger group of users and subsequently volumes have increased greatly. If you’re a new user of diamond blades, consider yourself lucky that you haven’t gone through the growing pains of the industry. Costs are as low as you will find overall, but there is still a wide range of pricing and quality levels available for you to choose from.
The biggest problem you will find now is trying to determine what makes sense for you to use. Unfortunately, there is no written standard on grading diamond blades. You will find blades labeled as “premium quality” that are really not. In fact, most marketers call their entire product line premium, regardless of true quality.
Bartell offers true blade grading, based on performance. We offer as many as six levels of quality depending on the product type. Our rule is that for every 15% more you spend, you should see a minimum of a 25% increase in performance. Most of our products exceed that rating.
So now that you know many of the quality ratings out there are meaningless, what should you look for in a blade? What’s right for one user probably won’t be the same for others, so let’s break this down by specific requirements. We’ll use 14” blades as the model since that is the highest volume product sold around the world.
A HEAVY USER SHOULD NOT USE INITIAL PRICE AS HIS GUIDE
Many users will look at the initial cost as the primary factor in their purchase. If you plan on making a small amount of cuts and don’t have any further need for the blade, this is the right choice. You want the lowest possible cost associated with the job. What you don’t want is something so cheap it may be dangerous. In reality, a heavy user should not use price as his guide. A higher priced blade will usually yield a much lower cost per foot than an economy blade. For Example;
Cutting 3000psi cured concrete with medium aggregate and #3 rebar these are estimated inch feet for Bartell brand blades by quality (+/- 30% depending on operator and saw):
- 14BSM0.4 – 1000 inch feet Average street price $55 Cost per in/ft - $.055
- 14BSM1.4 – 1500 inch feet Average street price $65 Cost per in/ft - $.043
- 14BSM2.4 – 3000 inch feet Average street price $80 Cost per in/ft - $.026
- 14BSM3.4 – 6000 inch feet Average street price $140 Cost per in/ft - $.023
As you can see your cost per foot drops more than the percentage of increased cost. If you cut often, a higher quality blade will save you on your cost per cut and will usually cut faster as well.
Safety - While a low price might seem like a bargain, it usually is not in the long run. Rule of thumb here is stay away from unmarked product.
If the manufacturer is not willing to put their name on it, you shouldn’t trust it. Look for branded products from reputable suppliers. It won’t necessarily make the price higher, but it will ensure a consistent quality product that the manufacturer will stand behind. Many internet sellers that represent themselves as “factory direct” have no direct contact with any factory. Make sure your supplier is insured in case of any problems. Blades with no markings make it hard to track the supplier.
Applications – The term “general purpose cutting” is thrown around repeatedly and this should not be confused with “combination cutting” or “multi-application cutting”. A general purpose blade usually means the bond is made to cut concrete, masonry block, brick or pavers (our application code 3 or 4). Do not count on this blade for cutting materials at the soft or critically hard end of the spectrum.
You generally will not find a low cost blade to cut all materials. The cost to produce specific application blades is much higher than general purpose
If you want to cut most materials without having to change, you need a true combination blade like our application code “C”. If you cut abrasive materials like asphalt or green concrete with a general purpose blade, it will wear out the blade as much as 70% faster than it would on the materials it was specified for. If you try to cut critically hard materials with a general purpose blade, it will glaze over and stop cutting. If you cut materials on either end of the hardness scale, you should use a blade specific to that application for best results.
Commonly asked questions:
- My guys don’t know how to cut properly, why should I give them a good blade when they will probably just destroy it? This is a question we hear a lot. A better quality blade will usually have a heavier steel core and have superior tension. The fact is that a “throw away” blade will fail much easier than a better quality blade. If your guys are destroying blades, give them something that will handle the abuse better. From a safety standpoint, economy blades in the wrong hands can be very dangerous.
- We cut large amounts of both asphalt and concrete. Does a combination blade make sense? In reality, you will have faster cutting and longer life by changing blades with each application. We often hear that it is impossible to get the operators to stop and change blades. If this is your scenario, a combination blade will keep your costs down overall and reduce the chance of damaging a blade due to misapplication.
- Does the height of the segment matter when it comes to the life of the blade? The answer is yes and no. Many low cost blades offer tall segments to make them look like they will last long. Usually, you will see a bronze look to the segment. This means they have produced a soft bond surrounding the diamond so that it wears quickly. This is necessary because the diamond is low quality and will not last long while cutting. If you compare a high quality blade with a 10mm tall segment, and they exact same quality with a 15mm tall segment, size does matter. Don’t get caught in the size game.
- What does the term inch foot mean? Inch foot means one lineal foot at 1” depth. If you are cutting ten feet at 4” depth you would have a total of 40 inch feet.
So what truly makes a good diamond blade? In reality it’s the best combination of cost, quality, speed and life that fits your needs. Take the time to evaluate what works best for you. Hopefully this might help save you time and money.
Saw blade with diamond grit bonded to the cutting surface
A close-up of a diamond blade, showing worn metal behind the diamonds on the 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]
References
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