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Composition of PCD and CBN


Composition of PCD 
(Polycrystalline Diamond)
Composition of CBN 
(Cubic Boron Nitride)
Materials recommended for 
cutting with PCD
Materials recommended for
cutting with CBN
Recommended Speeds and Feeds
of PCD
Recommended Speeds and Feeds
of CBN
Use and Care of Diamond Tools



 
Composition of PCD (Polycrystalline Diamond)
Polycrystalline Diamond (PCD) is a synthetic diamond product that is produced by sintering together selected diamond particles with a metal matrix using sophisticated technology. The diamond and matrix, when sintered together under high temperatures and pressures, creates a PCD tool blank that is high in uniform hardness and is abrasive resistant in all directions. This PCD diamond layer is then bonded to a tungsten carbide substrate, which provides strength and a brazable base to permit bonding to other metals.
Polycrystalline tipped tools are exceptionally resistant to wear compared to tungsten carbide or ceramic tools. In certain applications, PCD tool life can exceed carbide cutting tool life 50 to 100 times.
In certain applications, polycrystalline tipped tools have several advantages over natural diamond.
 
Shock Resistance
PCD is more shock resistant over natural diamond because of its random orientation structure of the diamond particles, and is backed by a carbide substrate.
 
Consistency
PCD is more constant in wear. Again because of the random orientation of diamond particles. Natural diamond is a single crystal in nature and has soft and hard grains. Depending on the shape of the natural diamonds and the tool being manufactured, it is sometimes not practical to have the hardest grain on the cutting edge.
 
Availability
PCD is readily available in a large variety of shapes and sizes. Discs as large as 60 mm in diameter are now available. Natural diamond is limited to what is formed in nature. Diamond, even with only an 8 mm long cutting edge is extremely difficult to find and is very costly.
 
Flexibility
PCD is a conductor. This allows us to routinely produce complex form tools and grooving tools with our wire EDM machines. Such tools are impossible to produce in natural diamond.
 
Cost
PCD blank costs are considerably lower than the cost of natural diamond stones, and the availability of different shape PCD blanks reduce manufacturing cost significantly. The longer of a cutting edge required, the larger the savings of PCD over natural diamond due to the rarity of larger stones.
Natural diamond and PCD diamond compliment each other. Natural diamond is denser than its PCD counterpart and consequently can be polished to a keener cutting edge.
Natural diamond is best suited to produce very fine finishes and precise tolerances as required in the manufacturing of jewelry, plastic contact lens, computer memory discs, and aluminum camera parts. See natural diamond tools.
Polycrystalline diamond tooling can be used in a wide range of machining operations such as milling, grooving, turning, facing and boring. They are recommended for machining nonferrous metals and abrasive non metallics.
Recommended Speeds and Feeds of PCD
Materials recommended for cutting 
with PCD
  • Aluminum and aluminum alloys 
  • Copper, brass and bronze alloys 
  • Zinc and magnesium alloys 
  • Gold and silver Tungsten carbide, pre sintered and sintered 
  • Carbon and graphite Ceramics, unfired 
  • Epoxy resins 
  • Plastics and rubber 
  • Fiberglass composites 
  • Graphite composites 
  • Phenolics Chipboard and fiberboard 

PCD cutting tools are available in various grades, 
depending on the application.
PCD 
Material 
Speed 
(SFM) 
Feed Rate (IPR)  Depth of Cut (INCH) 
Aluminum 
3000-5000 
005-.008 
.005- .020 
Aluminum 
(5-8% SI) 
4000-6000 
.010-.020 
.005-020 
Aluminum 
(8-12% SI) 
3000-5000 
.005.015 
.005-020 
Aluminum 
(14-18% SI) 
1000-3000 
.002010 
.003.015 
Copper 
750-1500 
.003-008 
.005-.020 
Bronze 
1000-1250 
.003-.008 
.005-.020 
Brass 
2000-4000 
003-.010 
.005-020 
Babbit 
800-1200 
.003-010 
.005-020 
Carbon 
500-1000 
.005- .015 
.005- .030 
Glass Fiber 
750-1000 
.001 -.010 
.001-002 
Carbon Composites 
500-2000 
.005- .015 
.0 10-.100 
Sintered Carbide 
30-50 
.004- .006 
0005-.005 
High Aluminum 
Ceramics 
1200-2400 
.001-.004 
.0005-005 
Wood and 
Composites 
8000-13000 
.010-100 
010-.100 
 


Top
Composition of CBN (Cubic Boron Nitride)
Cubic boron nitride (CBN) is an artificially synthesized material exceeded in hardness only by diamond. Unlike diamond, however, CBN is stable under conditions of high temperature (up to 1000°C) normally seen when machining hardened ferrous or super alloy materials.
Like polycrystalline diamond, CBN is available in a large variety of shapes and sizes. Discs are available up to 602 mm diameter. CBN is also available in several different grades, depending on the application.
CBN tools permit metal cutting at feeds and speeds much higher than conventional cutting tools materials. CBN tools are also being used to turn, bore and face hard materials, which previously could be formed only by grinding. Because CBN tools maintain a sharp cutting edge, part surface finishes are excellent, close tolerances are easy to maintain, and dramatic productivity increases can be expected.

 Recommended Speeds and Feeds of CBN
Materials recommended for cutting
with CBN:
  • Alloy steels (45-68 RC) 
  • Carbon tool steels (45-68 RC) 
  • Die steel (45-68 RC) 
  • High speed steel (45-68 RC) 
  • Chilled cast iron 
  • Ni Hard 
  • Forged steel 
  • Meehanite iron 
  • Moly chrome steel rolls 
  • Inconel 600 
  • Rene 
  • Incoloy 
  • Monel 
  • Stellite 
  • Colmonoy 
  • Waspoloy
C B N 
Material 
Speed 
(SFM) 
Feed Rate (IPR)  Depth of Cut (INCH) 
Carbon Steel 
200-500 
.008 MAX 
.020 MAX. 
Bearing Steel 
200-500 
.008 MAX. 
.020 MAX. 
Alloy Steel 
200-500 
.008 MAX 
020 MAX. 
Die Steel 
160-350 
.008 MAX. 
.020 MAX. 
Tool Steel 
160-350 
.008 MAX. 
.020 MAX. 
High Tensile Cast Iron 
200-500 
.060 MAX. 
.100 MAX. 
Chilled Cast Iron 
130-260 
.032 MAX. 
.100 MAX. 
Grey Cast Iron 
1000-2600 
.020 MAX. 
.040 MAX. 
Powdered Metal 
500-650 
.016 MAX. 
.120 MAX. 
lnconel 
500-650 
.006 MAX. 
.125 MAX. 
Rene 41 
500-650 
.006 MAX. 
.125 MAX. 
Rene77 
450-550 
.006 MAX. 
.015 MAX. 
Incoloy 
750~900 
.006 MAX. 
.125 MAX. 
Monel 
550-650 
.006 MAX. 
.125 MAX. 
Stellite 
550 -650 
.006 MAX. 
.125 MAX. 
Colmonoy 
550-650 
.003 MAX. 
.125 MAX. 
Waspoloy 
550-650 
.003 MAX. 
.060 MAX. 
 

Use and Care of Cutting Tools
Diamond cutting tools are easily damaged, so the cutting edges should be covered with rubber or plastic caps when they are not in use. Store them in separate containers when they are not in your machine.
When inspecting and setting up, use optical instruments if possible. Use copper shimstock or plastic between the cutting tool and micrometers or height gauges, if these are used, to avoid breaking the cutting edge. Don't bring the diamond into contact with the work in a stationary position or stop the machine during the cut.
High speed reduces cutting edge pressure; low speed increases it, causing diamonds to break down more rapidly.
Vibration also shortens tool life, so machine tools should be in good condition.

J & M DIAMOND TOOL, INC.
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             Updated 06/04/2001