Diamond abrasive knowledge collection
:yinglong :2017-09-15 09:18:44
Profile of Diamond
Diamond is the hardest material on the earth; much harder than corundum and silicon carbide. Diamond also has high strength, good wear resistance, and a low friction coefficient. So when used as an abrasive, it has many obvious advantages over many other common abrasives.
Advantages Of Diamond Grinding Tools
Diamond can be used to make grinding tools, which have following advantages:
- High grinding efficiency, Low grinding force: Less heat will be generated by the hole in the grinding process. This can decrease or avoid burns and cracks on the surface of the workpiece, and decrease the equipment's wear and energy consumption.
- High wear resistance: Diamond grinding tools' change in dimension is small. This can lead to good grinding quality and high grinding precision.
- Long lifespan, Long dressing period: This can greatly increase the work efficiency, and improve the workers' labor environment and decrease the product's labor intensity.
- Low comprehensive cost: The processing cost of each workpiece is lower.
Classification of diamond tools
There are thousands kinds of diamond tools. They can be categorized by their manufacturing methods and their uses. According to their manufacturing methods or bond types, diamond tools can be categorized to the following way:
- Metal-bonded diamond tools: The tools' bonding material is metal mixture powder. The functional parts of the tool are usually diamond segments. These tools include metal-bonded diamond saw blades, diamond grinding cup wheels, diamond core drill bits, etc. For metal-bonded diamond tools, the bond is one of the prime factors when selecting which tool to use for cutting or grinding a specific material, depending on how hard or abrasive the material is. The bond used dictates the rate at which the metallic powders wear down and expose new diamond crystals at the surface, thereby maintaining an abrasive cutting surface. Different bond strengths are achieved by the alloy mix of metallic powders chosen and how much heat and pressure are applied to the sintered segment.
- Resin-bonded diamond tools: The tools' bonding material is mainly resin powder. An example of this tool is the resin-bonded diamond polishing pads used in the construction industry.
- Plated diamond tools: This tool is made by fixing the diamonds onto the tool's base via electroplating method or via CVD (Chemical Vapor Deposition) method. This tool can usually be made to good processing precision.
- Ceramic-bonded diamond tools: The tools' bonding material is usually glass and ceramic powder. This tool usually has the features of good chemical stability, small elastic deformation, but high brittleness, etc.
- Polycrystalline Diamond (PCD): They are normally made by sintering many micro-size single diamond crystals at high temperature and high pressure. PCD has good fracture toughness and good thermal stability, and is used in making geological drill bits.
- Polycrystalline Diamond Composite or Compacts (PDC): They are made by combining some layers of polycrystalline diamonds (PCD) with a layer of cemented carbide liner at high temperature and high pressure. PDC has the advantages of diamond’s high wear resistance with carbide’s good toughness.
- High-temperature brazed diamond tools: This tool is made by brazing a single layer of diamonds onto the tool via a solder at a temperature of over 900 °C. This tool is a newly developed product. Its manufacture uses technologies include vacuum brazing and atmosphere-protected brazing. This tool has several advantages: the solder can hold the diamonds very firmly, the single layer of diamonds' exposed height can be 70%–80% of their sizes, and the diamonds can be regularly arranged on the tool.
What kind of workpiece is diamond tool suitable for?
Diamond tools are suitable to process the following materials:
- Carbide alloy
- Hard or abrasive non-metallic materials, for example, stone, concrete, asphalt, glass, ceramics, gem stone and semiconductor materials.
- Non-ferrous metals such as aluminum, copper and their alloys, and some soft but tough materials such as rubber and resin.
As diamonds can react with Fe, Co, Ni, Cr, V under the high temperatures generated in the grinding processes, normally diamond tools are not suitable to process steels, including common steels and various tough alloy steels, while the other superhard tool, cubic boron nitride (CBN) tool, is suitable to process steels. The tools made with common abrasives (e.g. corundum and silicon carbide) can also do the task.
