Tooling expert Walter GB has developed a new and innovative titanium aluminium oxide (TiAIN) coating process that revolutionises carbide insert performance by offering life increases of up to a staggering 200 per cent.

Compared to inserts that are coated using the conventional chemical vapour deposition (CVD) process, Walter's new Tiger.tec Gold inserts additionally boast higher wear resistance on flank faces, reduced hairline cracking, a greater resistance to plastic deformation, and improved process reliability.

The inserts will initially be available in the WKP35G grade for milling steel and cast iron; other grades will follow.

Recognising that CVD-coated aluminium oxide (Al2O3) inserts had reached a performance plateau, Walter AG set about developing a new TiAlN coating process. And, by using TiAlN with a significantly high aluminium content of 85 per cent - considerably higher than usual – in combination with a new 'ultra-low pressure' CVD process, the company has been able to 'separate' TiAlN for use as the main gold-coloured coating, which is ideal for tool wear indication.

Titanium nitride (TiN) is used as both a key between the carbide base substrate and the TiAlN coating, and as the top, textured layer (above the main coating).

In numerous tests at cutting speeds between 120 m/min and 320 m/min on various grades of steel and cast iron, the Tiger.tec Gold WKP35G inserts not only demonstrated extended tool life but also higher wear resistance on flank faces and improved resistance to plastic deformation.

This, says Walter, is attributable to applying the TiAlN coating by the 'low pressure' CVD procedure subjects the inserts/coatings to compressive residual stress rather than tensile residual stress.