1. Diamond Blade Fabrication
Diamond blades consist of four components: diamond crystals, a bonding system, a segment, and a metal core.

Diamond Crystals

The diamond crystals in MK blades are synthetic (man-made) rather than natural. This gives them a consistency that can be relied upon during the enormous stresses they encounter while grinding. The foremost performance factor in diamond-blade sawing is the type, concentration and size of these diamond crystals. The extensive diamond aptitude and sawing expertise MK has acquired goes into the selection of the proper diamond crystals for our wide range of blades.

Bonding Matrix

Diamond crystals are held in place by a sintering process of specially blended metal powders. This bonding matrix is crucial to the overall performance of the MK diamond blade and serves several vital functions:

• Disperses and supports the diamonds
• Provides controlled wear while allowing diamond protrusion
• Prevents diamond �pull-out�
• Acts as a heat sink
• Distributes impact and load as the diamond attacks the cutting surface

During the sawing action, the wearing away of the matrix exposes new diamond crystals providing fresh cutting points for the blade.

Metal Bonds

The diamond crystals and bonding matrix are heated and shaped into specially engineered rims / segments. These rims / segments are wider than the blade core to which they will be attached, and provide the clearance to promote material discharge and discourage blade binding. The rims / segments are specifically designed to wear at a rate appropriate to the material being cut. Large particles of soft, abrasive materials wear down the matrix faster than the small particles removed from hard dense materials. Therefore, softer, more abrasive materials require a �tough to wear� (hard) bond; less abrasive materials require an �easy wear� (soft) bond.

Premium Steel Core

The diamond saw blade cores are made from high alloy, heat-treated steel. Depending on the type of blade selected, the steel cores are specifically designed to support the appropriate rim or segment. About the periphery of the core, the various rims or segments are affixed through a brazing or laser welding process. An arbor hole is precisely bored in the center, and the entire core is �tensioned� or tuned so that the stresses of centripetal force are minimized, permitting the blade to spin true on the spindle.

2. Understanding Diamond Blades As Cutting Tools

In general, a diamond blade's performance is measured in two ways. The first is how proficiently the blade grinds through the material; the second is the life of the blade or total footage yielded by the blade. There are a variety of MK diamond blade models and designs from which to choose. Each blade is meticulously engineered to provide cutability, longevity and safety. When you select the best-suited diamond blade for the job / application / material, you will ensure peak performance and maximum investment return

How the Diamond Blade Works

Diamond blades do not really cut, instead they grind material through an action of friction with the synthetic diamond-bonding matrix. The diamond crystals, often visible at the leading edge and sides of the rim / segment, remove material by scratching out particles of hard, dense materials, or by knocking out larger particles of loosely bonded abrasive material. This process eventually cracks or fractures the diamond particle, breaking it down into smaller pieces. As a result of this phenomenon, a diamond blade for cutting soft, abrasive material must have a hard metal matrix composition to resist this erosion long enough for the exposed diamonds to be properly utilized. Conversely, a blade for cutting a hard, non-abrasive material must have a soft bond to ensure that it will erode and expose the diamonds embedded in the matrix. These simple principles are the foundation of �controlled bond erosion.�

Types of Diamond Blade Cutting

There are two basic types of cutting � dry or wet. The best choice of blade depends upon:

• The requirements of the job
• The machine / tool utilizing the diamond blade
• The preference of the operator

In the case of DRY cutting, the overwhelming popularity and quantity of hand-held saws and the flexible nature of MK Diamond blades to professionally handle most ceramic, masonry, stone and concrete materials, make the DRY cutting blade a very attractive tool. When using a DRY blade, the user must be aware of distinct operating practices to ensure optimum performance. DRY cutting blades require sufficient airflow about the blade to prevent overheating of the steel core. This is best accomplished by shallow, intermittent cuts of the material along with periods of �free-spinning� for several seconds to maximize the cooling process.

For WET cutting applications, MK has the exact blade to complement both the material to be cut and the wet-cutting machine to be used. During cutting operations, liberal amounts of water act as a coolant to support the cutting effectiveness and longevity of the WET blade. Additionally, using water adds to the overall safety of cutting operations by keeping the dust signature down

Know What You're Cutting

For maximum cutting speed and blade life, you should match the blade as closely as possible to the material you're cutting. Characteristics of the concrete you need to know include the compressive strength, the size and hardness of the aggregate, and the type of sand. Blade manufacturers consider concrete with a compressive strength of 3000 psi or lower a soft material and concrete with a strength above 6000 psi a hard material. Therefore, you should use a blade with a hard bond to cut the lower-strength concrete and a blade with a soft bond to cut high-psi concrete. Similarly, hard aggregate (such as trap rock, basalt, and quartz) dulls diamond particles quickly, so use a blade with a softer bond to allow new diamonds to be exposed as needed. The size of the aggregate in concrete primarily affects blade performance. When cutting through larger aggregate (3/4 inch and up), the blade cuts and wears more slowly. Pea gravel (smaller than 3/8 inch) is easier to cut, but the blade will wear faster. The type of sand determines the abrasiveness of concrete, with sharp sand being the most abrasive and round sand the least. To determine the sharpness of the sand, you need to know where it's from. Crushed or river bank sand is usually sharp while river sand is round and nonabrasive. The more abrasive the sand, the harder the bond requirement. What if you will be cutting more than one type of concrete? As a general rule, manufacturers recommend choosing the blade based on the material you'll be working with most often or the material for which top blade performance is most important. Most diamond blades can cut a range of materials.

Decide When You Want to Make the Cut

If you're placing new concrete, you have the option of cutting control joints while the concrete is still green (about 1 to 2 hours after finishing) or the next day after the concrete has hardened. The timing of the cut will dictate the type of blade you select. Some decorative concrete contractors prefer to cut concrete while it's still green because it minimizes the occurrence of ugly random cracking (especially in warm weather, when concrete hydrates faster) and permits shallower joint depths of an inch or less. However, green concrete will be softer and more abrasive than the same concrete in a cured state. That's because the sand in the mixture hasn't yet bonded to the mortar and it acts as an abrasive. Blade manufacturers offer hard-bonded diamond blades specifically for cutting green concrete.

Choose Wet or Dry Cutting

Often the decision of cutting wet or dry depends on your preference and job requirements. Dry cutting eliminates messy wet slurry and the need to equip saws with water tanks and hoses. Using a blade wet, on the other hand, reduces dust but makes it necessary to contain or clean up the slurry. For indoor jobs where you need to keep the work area dry, a dry-cutting blade and compatible saw may be your only option.

The main difference between wet and dry blades is the weld.. Dry-cutting blades have segment welds that resist heat and don't require water for cooling. They are usually intended for intermittent cutting and for use on handheld, low-horsepower saws. If you're sawing decorative pattern lines in concrete, dry-cutting blades are often the best choice for making crisp, clean cuts (see Sawing and Patterning). These decorative cuts are typically only 1/16 to 1/4 inch deep and do not function as control joints.

Wet-cutting blades are typically used with walk-behind saws for cutting joints in cured concrete flatwork because water cooling permits deeper cuts. Although it's possible to use most dry-cutting blades with water, never use a wet-cutting blade dry. Always continuously cool the blade with water to avoid segment loss and blade warpage.

Make Sure the Blade Is Compatible with Your Sawcutting Equipment

What type of handheld saw or flat saw are you using? What is the horsepower and operating speed (or rpm)? Blade manufacturers provide charts with recommended operating speeds and maximum safe operating speeds for their blades. You'll also find this information stamped right on the blade itself. Always match the blade with the speed range of the saw. Operating the blade at a lower speed than recommended can diminish its cutting life and performance. Exceeding the blade's maximum rpm rating can damage the blade and risk injury to the saw operator.

Other factors to consider:

• Blades designed for wet use only must be operated by saws that can deliver a continuous supply of water to cool the blade.
• Most blades for cutting green concrete are designed for use with special early-entry saws that minimize joint raveling and spalling.
• Don't use a blade that exceeds the maximum blade diameter and cutting depth capacity of the saw.

Choose Optimum Performance vs. Maximum Economy

Manufacturers typically offer diamond blades at various quality and cost levels, ranging from basic economy to top-of-the-line premium or professional versions. Generally the key difference among these options is the diamond content, which is the greatest raw material cost in manufacturing the blade. Moving up from a standard to a premium blade may boost the cost 20% or more, but you'll get a higher concentration of diamonds and significantly longer blade life. Basically, you need to decide what's more important: the initial cost of the blade or total sawing cost. For small cutting jobs where you won't be giving the blade much of a workout, you may save money by going with the economy blade. For large jobs or frequent use, a top-quality blade may actually be less expensive in the long run based on a cost-per-cut breakdown. A premium-quality diamond blade isn't cheap. Expect to pay several hundred dollars or more, depending on the blade diameter. If that's more than you're willing to invest for an occasional cutting job, consider hiring a professional sawing contractor to do the work. To locate a contractor in your area, visit the member directory of the Concrete Sawing & Drilling Association (CSDA).

Determine if a Decorative Cut Is Important

Want to achieve the look of a decorative hand-tooled joint without all the labor? It's possible by using beveled saw blades with a special cutting edge that produces chamfered or radiused cuts in green concrete. Learn more about the applications of these blades for decorative concrete projects.

Look for the CSDA Code

If you follow all of the steps, you will be armed with the information necessary to find exactly the type of diamond blade you'll need for your next sawing project. Now it will be easier than ever to identify whether a certain blade meets your requirements thanks to a new blade application code (PDF) developed by CSDA and endorsed by the Masonry and Concrete Saw Manufacturers Institute (SMI). The code, which is in a three-letter format separated by dashes, will be permanently imprinted on the blade. And it will tell you at a glance whether the blade is for wet or dry use, what type of material it can cut, and the saw type it's designed to work with.