Cryo machining

A revolutionary and promising technique for working metals
Manufacturing & Process
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26 July 2017

Traditional cooling fluids for turning and milling are necessary but have some major disadvantages. Thanks to Cryo Machining, there is now a technology that offers a cost-effective and environmentally friendly solution.

Traditional cooling fluids for turning and milling are necessary but have some major disadvantages. A great deal of research has been done to eliminate these disadvantages as much as possible, but it has only succeeded to a certain extent.

Until recently, these disadvantages had to be taken into account. Thanks to Cryo Machining, there is now a technology that offers a cost-effective and environmentally friendly solution. This technique means that liquid nitrogen (LN2) is used as a coolant during machining.

Due to its extremely low temperature, liquid nitrogen is very suitable for this. For some metals that react badly to this cold, liquid CO2 can be used. Cryo Machining solves problems that traditional coolants have to a greater or lesser extent, such as insufficient cooling capacity, the workpiece is partially soiled by the coolant, they cause harmful vapours and toxic waste, etc.

Cryo Machining: faster, better quality and more environmentally friendly

Air Liquide is one of the pioneers of this technique and has invested a great deal in research into its advantages and practical applicability. The advantages that are already apparent are interesting and represent a significant improvement in the cutting process.

Pia Biermann, project manager for Cryo Machining at Air Liquide, confirms that the tests currently under way in trial companies are very positive: “the processing speed of metals increases by 20% thanks to this technique and is still being refined and improved. So you can cut faster, cool optimally, it’s more environmentally friendly and the machining tools wear less quickly.”

One of the major advantages of Cryo Machining is indeed that it increases the life of the machining tools. Scientific research shows that these tools need to be replaced less frequently, which reduces the need for downtime.

The metal processing speed also increases by an average of 20% thanks to Cryo Machining. This process efficiency is an important asset for companies that often cut metals. The improved surface roughness is striking and very interesting for metalworking companies. This roughness is significantly less when Cryo Machining is used. Various studies have shown that surface roughness is nearly halved compared with traditional machining fluids and is many times less than when no additional fluids are used. Certainly after ten minutes of machine time, the difference in surface roughness increases dramatically.

Cutting temperatures remain much lower than those of other cutting techniques, with all the associated advantages. For example, there is less burr formation during machining. Various tests (e.g. by expert Cordes) indicate that 55% less burr formation occurs on the cutting edges when working with Cryo Machining. The rest of the workpiece and machining tool are also better freed from wear due to heat.

Ce graphique présente les différentes températures des composants du processus d’usinage. Dans le premier cas, le CO2 est utilisé, dans le deuxième cas, le travail a été réalisé avec de l’azote liquide. (Source: «Next generation high performance cutting by use of carbon dioxide as cryogenics » Cordesa, Hübner, Schaarschmidt).

The improved surface roughness is striking and very interesting for metalworking companies. This roughness is significantly less when Cryo Machining is used. Various studies have shown that surface roughness is nearly halved compared with traditional machining fluids and is many times less than when no additional fluids are used. Certainly after ten minutes of machine time, the difference in surface roughness increases dramatically.

This graph shows the different temperatures of components in the machining process. In the first case CO2 is used, in the second case liquid nitrogen was used. (Source: “Next generation high performance cutting by use of carbon dioxide as cryogenics”, Cordesa, Hübner, Schaarschmidt)

This technique also represents a particular improvement for the environment and air quality in the workshop. When this coolant comes into contact with the air, no harmful vapours are formed. The liquid nitrogen is then converted into nitrogen, a natural component of the air.

Air Liquide offers Cryo Machining and continues to invest heavily in research into this promising technology. Extensive pilot projects are currently under way in various types of companies to map out the benefits more precisely. In addition, Air Liquide is working on a research project with Sirris to develop a head which delivers even better cooling performance than the current systems.

Cryo Machining works with liquid nitrogen (LN2) or with CO2. Liquid nitrogen has better cooling performance (see graph above) but cannot be used for all metals. Sometimes it is necessary to use CO2 instead of LN2 when cutting metals that do not tolerate cold well.

Companies that never work with LN2 also have to pay more attention to safety. Working with liquid nitrogen involves risks. In order to limit these dangers, however, many safety systems exist. This allows companies to work perfectly safely with LN2.

6 advantages of Cryo Machining

Pia Biermann believes strongly in the unique properties of Cryo Machining and summarises the most important benefits:

  • the machining tools wear out less quickly
  • there is a better quality of the cut edge and surface roughness
  • the technique is less polluting
  • the processing speed is increased
  • the machined part is not contaminated by working fluids
  • much less air pollution occurs during processing
  • The technology thus offers major economic and environmental benefits.
  • Moreover, the cost price of the installation differs little from the traditional cooling systems, but it increases the quality and processing speed.

The environmental benefits are another important asset of Cryo Machining. A great deal can therefore be expected from this technique.

Source: in cooperation with Air Liquide

Article written by METAAL INFO

www.vlamef.be
 

Learn more about cryogenic processing

Contact our specialist in cryo machining, Wim Velghewim.velghe@airliquide.com

 

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