Mark Stanford, a lecturer at the University of Wolverhampton, is currently evaluating the benefits of metalcutting in the presence of an inert gas using a Enshu EV450 4-axis machining centre

The benefits of metalcutting in the presence of an inert gas such as nitrogen are becoming better known, but practical applications are few. Mark Stanford, a lecturer in the Division of Engineering at the University of Wolverhampton, is currently evaluating the benefits of the technique using a Japanese-built Enshu EV450 vertical-spindle, 4-axis machining centre. It has been fitted with a nitrogen pack which is believed to be a world first in that it extracts nitrogen in real time from the ambient air, eliminating the need for expensive gas bottles.

The equipment was supplied to the university earlier this year by UK sales agent, Yuasa Warwick Machinery.

The first such facility to be installed in the UK or indeed in Europe, it will be used not only for research into alternatives to environmentally unfriendly flood coolant systems, but also to introduce the technology to manufacturing companies in the West Midlands and throughout the UK.

The latter is the remit of the Innovative Product Development Centre, the first major initiative of the Competitiveness Centre at the University of Wolverhampton.

Headed by Dr Alan Collins, both operations have been set up with the help of European regional development funds to help UK companies become more competitive by taking commercial advantage of advanced product development and manufacturing technologies.

Suitable for use on any fully guarded Enshu machining centre with through-tool coolant facility and coolant jets, the nitrogen extraction system is mounted directly to the side of the machine and requires only an electrical supply for operation.

The continuous stream of nitrogen which is separated from the air is directed at the point of cutting in the same way that air or coolant is in conventional systems.

One important use of nitrogen machining is for high speed milling of magnesium, a combustible metal used more and more in the automotive industry owing to its lightness and strength.

Tests have shown that dry cutting speed can be increased dramatically from 30 to 150 m/min when machining magnesium without fear of igniting the swarf.

There are benefits too when cutting harder materials like cast iron and steels up to Rc 60.

One advantage is the elimination of coolant, which is costly to buy and to dispose of.

The environmental aspects of machining are also particularly relevant today in view of the increasing importance of ISO 14001.

Another advantage is that tool life is increased due to the minimal oxidation and lower localised temperature at the cutting tip, evidenced by the absence of blue chips when machining steel at elevated speeds.

Moreover the higher the rpm, the greater the longevity of the tool compared with conventional cooling.

In some high speed machining applications, a sixfold increase in tool life have been obtained.

Further benefits of reduced tool wear are improved dimensional accuracy of the machined component and better surface finish.

Mark Stanford's areas of research will include the operational effectiveness of nitrogen machining, workpiece and tool materials, cutting forces and seizure, tool life, and the tool / chip interface with particular emphasis on cooling properties.

As oxygen acts as a lubricant in conventional dry cutting, its absence may require the combination of nitrogen with minimal volumetric delivery of cutting fluid.

Mark will look into this also.

There are already a number of Japanese manufacturers using nitrogen machining in a controlled production environment, but none yet outside the Far East.

Both the Innovative Product Development Centre and Yuasa Warwick Machinery, for their separate reasons, are determined that the UK will lead the way in Europe.