A diamond grinding wheel, also known as the diamond wheel, is fairly new compared to other types of abrasive cutting tools. It is a metal bonded grinding tool with diamond segments either cold-pressed or welded on the wheel body (typically made of steel, aluminum, etc.). Diamond grinding wheels are generally mounted a concrete grinder to grind extremely hard, abrasive building materials, such as granite, marble or concrete.
Diamond grinding wheels can take various shapes, such as cups, flat discs, cylinders, cones, wheels with profiles cut into their periphery, and so on. Diamond grinding wheels are generally categorized by shape, concentration, grit size and bond. The grit size of the abrasive is chosen for the diamond grinding wheels typically depending on the hardness of the cutting material.
There are two common ways of manufacturing diamond grinding wheels: cold press and hot pressing.
● Hot Pressing:
This method requires the use of a dedicated sintering press machine to directly sinter the diamond segments in molds with a given pressure. Then, the diamond segments are fixed onto the grinding wheel using laser welding, high-frequency welding or other welding methods.
● Cold Pressing:
This type of manufacturing method involves pressing both layers (i.e., the working and transitive layers) of the diamond segments directly on to the body of the grinding wheel so that the segment can conform to the grinding wheel’s body via slots and teeth. Lastly, the grinding wheels are placed into the sintering furnaces to undertake the sintering process without pressing.
Diamond grinding wheels come in different specifications and styles which are meant for various applications. For instance, diamond grinding wheels with exceptionally big diamond segments are used for heavy, hard tasks, such as grinding stone and concrete. Whereas grinding wheels with smaller diamond segments are better at removing paints, wallpapers, epoxy, glue and other surface coatings.
Diamond grinding wheels can have different bond, grit size, material, concentration, etc., all of which define the wheel with respect to its application. As a matter of fact, the application of diamond grind wheels has very much to do with the bond. For instance, softer bonds should be used to grind harder materials; harder bonds should be used to grind softer materials.
Moreover, the roughness of the object also determined the type of diamond grinding wheel you should use. For coarse grinding, softer bond should be used with higher quality diamonds. If not, the diamond can become blunt very quickly. Bigger diamond grit should be used (typically from 35 grit to 50 grit) to improve the efficiency of coarse grinding. Furthermore, the concentration of diamond should be lower in this case.
Lastly, the bond of the grinding wheel should be harder for fine grinding to help enhance the precision of the process. The quality of diamond can be lower and the concentration of diamond should be higher. As a result, the diamonds will be able to last longer. For fine grinding, the diamond grit generally ranges from 80 to 120 grit based on the grinding requirements.
Dressing in grinding is the act of removing grains and chips on a dulled grinding wheel due to glazing or loading. Dressing is performed using proper dressing tools to sharpen the dulled cutting edges by proper extruding to grain cutting edges. Here are the simple steps of dressing a diamond grinding wheel:
1. To dress a diamond grinding wheel, obtain a dresser finer (typically by one or two grit sizes) than the abrasive in the diamond.
2. Turn off the coolant pump.
3. Turn on the grinding machine for the grinding wheels to reach maximum RPM, and then shut down the spindle motor once it does.
4. Apply the dresser from step 1 against the abrasive section of the grinding wheel with light to medium pressure until the wheel stops spinning.
5. You should begin to feel that the dressing stick is being drawn into the grinding wheel at this point. When you do, repeat all of the steps above. You have to repeat this process three to five times over depending on the condition of the grinding wheel.
With reference to step 1, some of the common multi-point dressers (or dressing sticks) that you can choose from include multi-point diamond dresser, blade type multi-point diamond dresser, impregnated diamond dresser, and bond diamond dresser. Also, some of the common single-type diamond dressers include, the standard dresser, cone type dresser, wedge type dresser, and Reischauer dresser. As a friendly note, do not use a single-point type dresser for wheel truing processes.
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