Tools made from polycrystalline diamond and tungsten carbide: when and why to choose them

Tools made from polycrystalline diamond and tungsten carbide

When we talk about tools for machining panels within the furniture industry, the choice tends to be between two categories: those made from polycrystalline diamond, and those made from tungsten carbide.

In the following paragraphs, we will attempt to analyse some of the key characteristics of these two tool types, before providing some useful guidance for deciding when polycrystalline diamond tools are a better choice, and when tungsten carbide tools are a more suitable option. However, it is important to remember that the choice of tools is influenced by a number of variables, linked to the specific machining operations to be performed and the requirements of each individual user.

When and why to choose tools made from polycrystalline diamond (PCD)

Polycrystalline diamond is a composite material which consists of diamond particles sintered together with a metallic binder.

Diamond is naturally an extremely hard material, a quality owed to its cubic crystalline structure. This structure is very compact, as it is solely composed of tiny carbon atoms arranged in a tetrahedral shape, which creates very strong bonds with all the surrounding atoms.

For more than a century, we have been attempting to reproduce these extreme conditions in order to create synthetic diamond, but it was General Electric that finally succeeded in obtaining the first industrial diamonds, by subjecting graphite (the other crystalline form of carbon with a hexagonal structure) to temperatures of 2-3000 °C and pressures of 50-100,000 bar, using nickel, iron and cobalt as catalysts. In the seventies, GE created CBN (Cubic Boron Nitride), followed by polycrystalline diamond (PCD) and Polycrystalline Cubic Boron Nitride (PCBN).

The natural hardness of polycrystalline diamond makes it an excellent material for cutting operations, ideal for use in tools for milling, panel sizing and boring, and the prevalence of this material in applications within the wood machining industry has been growing exponentially for a number of years.

characteristics of tools made from polycrystalline diamond

Of the primary characteristics of tools made from polycrystalline diamond, the following are of particular note:

  • extreme hardness
  • low friction
  • high resistance to wear
  • greater cut duration
  • optimal finish quality

These characteristics make tools of this type particularly suitable for machining materials such as:

  • chipboard
  • laminated materials
  • MDF/HDF
  • fibreglass
  • carbon fibre
  • PVC
  • CORIAN
  • HPL
  • etc.

Their use should be avoided on ferrous materials.

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When and why to choose tools made from tungsten carbide (HW)

Tungsten carbide (also known as Widia) is a material composed of hard particles, usually of tungsten carbide, incorporated into a metal matrix (often cobalt), and for this reason, it is categorised as a cermet (a composite composed of ceramic and metal materials). This combines hardness (resistance to wear) with resistance to cracking.

It was German colleagues Karl Schroeter and Henrich Bauhmhauer who first succeeded in sintering tungsten carbide in 1923, at the Osram Lamp Company, whilst attempting to produce a material that could cut tungsten into very thin filaments for use in light bulbs. Friedrich Krupp patented this process, and in 1926, his company began production of a material that they called Widia (from the German “Wie Diamant”).

In 1928, the American company General Electric bought the rights for the production of this material in the USA, where it was marketed as Carboloy.

The primary characteristics of tools made from tungsten carbide are:

  • high resistance to wear
  • high toughness

These tools are primarily used in chip removal when machining hard materials.

characteristics of tools made from tungsten carbide

They are most commonly used in machining operations where the type of material processed in a given day often varies, and where a high quality finish is not required: the cutting edge of tungsten carbide tools begins to deteriorate from the very first phases of cutting.

Analysis of the characteristics and costs of tools in polycrystalline diamond and tungsten carbide

In addition to the technical considerations, the choice between tools in polycrystalline diamond and tungsten carbide is also influenced by cost. Those made from tungsten carbide are significantly cheaper to buy than their polycrystalline counterparts, but does this translate into a real saving when the overall costs of production are taking into consideration?

Let's take a look at a few key facts. First and foremost, before purchasing a tool, it is essential to ask ourselves a few questions:

How many times can I sharpen this tool?

How much will it cost me to sharpen it?

How much time will it take me to fit/remove and reset the machine during sharpening?

The answers to these questions can be found by analysing the main differences between diamond and tungsten carbide tools.

Cut duration

On average, diamond tools have a cut duration that is 50 times greater than that of tungsten carbide tools (the figures can vary in accordance with the material machined, the machining speed etc.)

Cut quality

Both diamond and tungsten carbide tools initially offer excellent cut quality, but right from the very first phases of cutting, tungsten carbide begins to deteriorate, while the quality of diamond tools remains unchanged from the first sharpening.

Resharpening

Tungsten carbide tools must be resharpened more often than those made from polycrystalline diamond. This means:

  • more machine downtime
  • longer machine reset times
  • greater number of spare tools required.

The experience of Wirutex hi-tech tools

As we have just seen, when choosing the right tool material for your needs, it is important to consider the type of wood you will be machining and the machining finish that you require, as well as performing a careful analysis of the costs involved.

Making a mistake during the evaluation process could have a very negative effect on the production process, both in terms of machining quality and operating costs.

Precisely for this reason, it is beneficial for customers to find a tool manufacturer they can rely on, with the ability to direct them towards the products most suited to their requirements.

Wirutex hi-tech tools is the ideal company for operators who want to be able to place their trust in a technological partner with a wealth of experience in the field. The extensive range of high-quality polycrystalline diamond and tungsten carbide tools available is a direct result of the company's ongoing investment in innovative technologies, which enable the application of cutting-edge design, development and production processes.

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By Redazione |
21 November, 2018
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Utensili hi-tech