Coolant can achieve 20% increase in cutting speed

The demand for faster, cheaper, and greener aerospace solutions comes with challenges. CO2 emissions have been the main focus, but the impact of manufacturing operations is equally crucial. Fortunately, a solution is correctly applying coolant to maximise output, enhance process security and improve tool performance. Here, Henri Sevonen, Senior Industry Segment Manager – Sandvik Coromant, explains the benefits of high-precision coolant and tooling concepts.

The role of coolants has undergone somewhat of an evolution. Machine shops have used coolants by directing tubes that flood the machining zone, particularly on the materials that need coolant to be machined. But now, by applying coolant with high precision accurately into the machining zone, new advantages are available.

If coolant is to be applied effectively and make a difference, it needs to be applied as jets at high precision, in sufficient volume and directed correctly. Qualified applications can make a distinct difference in chip formation, heat distribution, surface integrity and tool wear. When applied correctly, precision coolant maximises output, increases process security and improves tool performance and component quality. The positive effects start at low coolant pressure, but the higher the pressure is, the more demanding material can successfully be machined.

Precision coolant application can make a difference to machining in general, but when machining more demanding materials, such as heat-resistant super alloys (HRSAs) and titanium alloys, the practice makes a dramatic difference.

Many modern CNC machines have coolant supplies at pressures of 70 to 100 bar. This is sufficient to incorporate high-precision coolant, which makes a noticeable performance difference.
An essential basis for high-precision coolant use is modular tools to ensure quick tool changes for minimising machine stoppages. The modular Coromant Capto® tooling system is the basis for new standard high-precision coolant tooling. This modular platform designed with an internal coolant supply is also suited as the means with which to supply coolant at high precision. It is an established ISO standard and an option on many CNC machines with stationary and rotating tools.

Turning tools with precision coolant are equipped to give accurate coolant jets with laminar parallel flow. The jets give rise to a hydraulic wedge between the insert and chip, affecting the chip form and flow and reducing the temperature in the machining zone. Employing nozzles, mounted close to the cutting edge, accurately projecting the high-velocity jets, forces the chip off the insert face and cools and breaks the chips into smaller lengths, helping to evacuate them.

Benefits in finishing operations have been established even at lower pressures, down to ten bars in material including steel, stainless steel, aluminium and heat-resistant superalloys. Apart from higher security brought about by better chip control, precision coolant can bring about considerable tool life improvement and a potential for higher cutting speed. By applying precision coolant, 50% tool life increases can be the result.

Precision coolant can play a vital role in ISO S machining. The effect of precision coolant can therefore provide the potential to raise performance by way of higher cutting speeds without the usual rise in temperature and loss in tool life. There is a clear cooling effect and not the higher cutting forces through higher feeds. For ISO S-classified materials, a 20% increase in cutting speed can be achieved while maintaining the same cutting length.

Internal turning is also an area where precision coolant can play an important role in helping ensure good chip formation, as well as improving shearing properties in demanding materials such as titanium. In this way, the concept adds higher security and longer tool life to boring operations. When machining relatively large, deep holes with boring bars, such as in landing gear components, modular tooling at the back as well as the front end of the tool can be advantageous.

Being able to change the small cutting head on the clamped bar provides quick, easy and accurate changing, adding considerable flexibility for various cuts in one set-up. The CoroTurn® SL combines damped boring bars with serrated locking heads for boring larger holes with depths of ten times the diameter and this is also equipped with precision coolant facilities.