PDC（Polycrystalline Diamond Compact ) cutter bit inserts are sintered with selected diamond powder and tungsten carbide under high temperature and ultra-high pressure. PDC’s have high hardness, wear resistance and impact resistance, are widely used for oil/gas well drill bit, rock drill and coal mining bitalso could be used for diamond tools for cutting, grinding, polishing.
The invention of the PDC cutter propelled the fixed cutter to the forefront of the drilling industry and the idea instantly took off. Because the shearing action of PDC cutters are more efficient than the crushing action of a button or tooth bit, fixed cutters are in high demand.
In 1982, PDC drill bits accounted for only 2% of total footage drilled. In 2010, 65% of total footage drilled was by PDCs.
The diamond drill bit is used in nearly all applications including geothermal energy drilling, mining, water well and natural gas drilling and oil well drilling. Total depths range from 100' to 20,000'. PDC drill bits are used extensively in natural gas drilling.
PDC also has some limitations like impact damage, heat damage and abrasive wear all inhibit a drill bit's performance and can occur in even the softest geological formations. However, the most difficult formation for a PDC bit to drill are extremely abrasive ones. With PDC popularity on the rise, bit manufacturing companies are seeking new materials and design aspects to make a tougher bit without compromising ROP.
Cutters are made using a combination of high heat and high pressure. Man made diamonds can be grown in 5-10 minutes. Because of this diamond content, a fixed cutter bit may also be known as a diamond drill bit. High heat plus pressure creates a PDC (polycrystalline diamond compact) cutter. Cutters are made from a carbide substrate and diamond grit. High heat of around 2800 degrees and high pressure of approximately 1,000,000 psi forms the compact. A cobalt alloy is also present and acts as a catalyst to the sintering process. The cobalt helps bond the carbide and diamond.
A diamond grinding cup wheel is a metal-bonded diamond tool with diamond segments welded or cold-pressed on a steel (or other metal, such as aluminum) wheel body, which usually looks like a cup. Diamond grinding cup wheels are usually mounted on concrete grinders to grind abrasive building materials like concrete, granite and marble.
There are various styles and specifications of diamond grinding cup wheels to fit various application requirements. The ones with many big diamond segments can undertake heavy workloads, for example, grinding concrete and stone, while those with small or sparse diamond segments are normally used for fast removal of paints, wallpapers, glues, epoxy and other surface coatings.
Just like other metal-bonded diamond tools, the diamond segments on diamond grinding cup wheels can have different bonds, different diamond grits, different diamond quality and different diamond concentrations to fit different uses. For example, if the material to be ground is hard, the bond should be softer, and if the material is relatively soft, the bond should be harder.
Diamond grinding cup wheels are used in different-roughness grindings. For coarse grinding, the bond should be softer and the diamonds' quality should be higher, because in this case the diamonds become blunt more easily. The diamond grit should be bigger, normally from 35 grit to 50 grit. For this is coarse grinding and big grit can improve working efficiency. The diamond concentration can be lower.
For fine grinding (sometimes called "polishing"), the bond should be harder and the diamonds' quality can be lower, as in this case the diamonds can last longer and a hard bond can also help the precision of the process. The diamond grit is normally between 80 grit and 120 grit, depending on the grinding requirements. The diamond concentration should be higher.
After being ground, the material can be further polished with resin-bonded diamond polishing pads of different diamond grits.
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