ADVANCED CUTTING MATERIALS

Advanced cutting materials are advanced metal-cutting tool materials, they differ a lot from the common ones. They are much harder than common ones, such as carbides, and they have a range of properties and applications. Advanced materials include cermet, ceramic, cubic boron nitride (CBN), Polycrystalline Diamond (PCD) and Polycrystalline cubic boron nitride (PCBN).

Why do we use advanced cutting materials and not common carbides?

Even though Carbon tool steel is one of the inexpensive metals cutting tools used for low-speed machining operation, some materials need expensive cutting tool materials to make the machining process flawless. Advanced cutting materials’ main benefits are their ability to cut hard, abrasive, and ductile materials, perform precise cuts, and cut at higher speeds.

Many workpiece materials, such as superalloys and cast iron, respond best to being cut with advanced tool materials. Advanced materials can also improve the efficiency and accuracy of machining operations. An operator who understands advanced tool materials will be able to cut more kinds of materials effectively, increasing flexibility and reducing scrap and waste.

Advanced cutting materials comparison table

PROPERTY CARBIDE CERAMIC CBN PCD

Hardness [HV]

1,300-1,800

2,100-2,400

4,500-5,000

5,000-6,000

Machining Hard Steel

10 - 45 HRC

50 - 100 mm/min

160 - 320 SFM

40 - 60 HRC

100 - 300 mm/min

330 - 660 SFM

50 - 70 HRC

150 - 350 mm/min

500 - 1150 SFM

N/A

Machining Cast Iron

200 - 300 mm/min

650 - 1000 SFM

400 - 800 mm/min

1300 - 2600 SFM

500 - 2000 mm/min

1500 - 6500 SFM

N/A

Machining Super Alloys

20 - 60 mm/min

65 - 200 SFM

150 - 400 mm/min

500 - 1300 SFM

100 - 400 mm/min

330 - 1300 SFN

N/A

Machining Aluminum

300 - 800 mm/min

1150 - 2600 SFM

N/A

N/A

600 - 2500 mm/min

2000 - 8000 SFM

PCD

As mentioned above, PCD stands for “Poly Crystalline Diamond”, the hardest available cutting material. PCD is a synthetic diamond produced by sintering together selected diamond particles with a metal matrix at high temperature and high pressure. Based on how they are made, it makes them resistant to abrasion, and wear and tear. PCD is for any speed, period, in nonferrous materials. It will leave a good finish at low surface speeds, and it won't break down at ridiculous speeds (10k+ SFM). It also lasts much longer than any other type of insert, usually orders of magnitude longer.

Main Uses
  • PCD tools are limited to non-ferrous materials, such as high-silicon aluminum, metal matrix composites (MMC), carbon fiber reinforced plastics (CFRP), titanium, platinum, copper, brass and bronze alloys, and polycarbonate
  • PCD with flood coolant can also be used in titanium super-finishing applications.
  • You can use PCD tools for machining aluminum and alloys, tungsten carbide, copper alloys, laminate floors, ceramics, glass fiber, graphite, and carbon fiber. This makes polycrystalline diamond extremely useful in manufacturing.
  • PCD tools also provide greater dimensional accuracy for precise metal finishing.
  • PCD tools have faster feed rates, as well as a long cutting lifetime.

    • PCBN

    Polycrystalline cubic boron nitride, PCBN, is a cutting tool material that contains iron because when making the CBN diamond, carbon is replaced with Boron and Nitrogen. This causes CBN diamond to be very resistant to high cutting heat of 1300°C. Therefore, it is an optimum choice for using CBN cutting tools for cutting workpieces that contain iron.

    However, when compared to PCD or a natural diamond, CBN diamond has a hardness value of 4700 Knoop Hardness, while a natural diamond has a hardness value of 8,000 to 9,000 Knoop Hardness, which is more than CBN diamond.

    Main Uses
  • CBN is more suitable for high temperature with dry cutting condition when machining hardened ferrous metals.
  • CBN inserts are used only for finishing operations that require higher surface finish and accuracy that cannot be obtained with Ceramic Inserts
  • CBN inserts solved so many difficult problems that met in past times. Common Field that CBN Tools used for as follows: 1. Alloy steels, Carbon tool steels, Die steel, High speed steel, Forged Steel (45-68 RC) 2. Cast Iron, Hi Cr Cast Iron, Chilled Cast Iron, Grey Cast Iron, etc.
  • Considering that CBN is ten times more costly than ceramic for the same size and geometry insert, CBN economically can be justified only for machining heat treated steel in those situations where ceramic fails completely or breaks down before finishing the workpiece.
  • To make best use of CBN, cutting parameters must be maintained within a tight band. Speeds around 160 SFM and feeds of just 0.004 to 0.006 inch per tooth appear slow, but they are highly productive when machining sintered materials. Exact machining parameters are best determined by 30- to 60-second test cuts. Start at low speeds and build up until cutting edges show excessive wear.

    • Ceramics

    Ceramic cutting tools are constructed mainly from alumina (Al2O3) and silicon nitride (SiN). Recent advances have also introduced the use of silicon carbide (SiC) and ceramic matrix composites (CMCs) to enhance the performance of the cutting tool.

    Each of these ceramic materials has its own characteristics, but, in general, they all exhibit excellent hardness, toughness and thermal conductivity. In fact, the advantages of using ceramic materials in manufacturing revolve around ceramic’s greater ability to withstand much higher temperatures than tools made from carbide or high-speed steel. Ceramic tools’ heat resistance exceeds 4000°F vs. about 1600°F for tools made from carbide powder.


    Main Uses
  • Ceramics are used at high temperature machining because it can withhold as much as 3000°F, unlike carbide and cement tools that contain metallic binders and begin to soften at temperatures greater than 1,000°F. It does not soften or crack.
  • Whiskered ceramics work best on hard ferrous materials and difficult-to-machine nickel-base alloys. They do not work well on ferrous alloys below RC 42 hardness because of the chemical reaction that occurs between iron and the carbon that is part of the silicon carbide reinforcing material.

    • Cermet

    Like the name implies, cermet combines ceramic elements (such as TiC, TiCN and molybdenum carbide) with metallic binders (such as nickel, as well as molybdenum and cobalt to a lesser degree), it is however more brittle than tungsten carbide


    Main Uses
  • They are mainly used for cutting carbon and alloy steels to tight tolerances.
  • Cermet can also be used to cut stainless steels and even high-temperature alloys. It should not be used to cut cast iron and aluminum; ceramics can do that.