Although a large part of the heat generated by turning is dissipated in the chip, the temperatures prevailing in the cutting zone are enormous and this causes problems for the cutting tool. The heat can reach temperatures in excess of 1000degC, depending on the material, feed and rpm. This activates thermal processes that cause the cutting tool to wear more quickly. In extreme cases, the tool can even burn out after a short time. A more positive geometry and cutting speed adapted to the process may provide a superficial remedy, but this either causes long-term costs or lowers productivity.

Feeding coolant directly to the cut point

Of course, cooling is necessary. However, the commonly used external cooling method is not precise in application and its true effect is limited. In fact, the relatively imprecise and uncontrolled flooding of coolant or oil into the cutting process cools the chips instead of the cutting edge. In many cases, the high temperature differences at the cut point cause a thermal shock that fatally damages the cutting edge.

On the other hand, through tool cooling acts in a controlled and precise application. There are tool manufacturers who have succeeded in feeding coolant directly to the cut point, the actual problem zone, via bespoke and dedicated tooling systems. Tool manufacturer ARNO Werkzeuge was awarded the highest honours by the patent office for the ARNO Cooling System^® (ACS): it succeeds in feeding coolant directly to the cut point via two channels from the top and from the bottom.

Part Off tooling and the patented ACS2 double coolant supply method

ARNO Werkzeuge has developed the field-proven ACS system in two variants. With the ACS1 variant, the coolant jet is guided along the insert seat in a coolant channel and emerges directly at the cutting zone. The coolant then effectively goes under the chip and optimally flushes it out of the cutting zone. This drastically lowers wear and significantly prolongs the service life of grooving and parting tools. With the ACS2 variant, the coolant channel at the insert seat is coupled with a second flow-optimised coolant jet from the bottom onto the tool flank. The latest developments offer this coolant channel with a triangular outlet which supplies coolant across the full width of the insert right through to the edge.

Tool set up and application is optimised also. Whereas the optimum coolant supply of an external cooling system is manually positioned and, often, inaccurate in application the internally guided coolant jet always goes precisely where it has the greatest effect – to the cutting zone and the tool flank It also minimises the risk of material build-up on the cutting edge and the associated crumbling of the cutting edge.

Additive manufacturing opens up previously unforeseen possibilities.

ARNO have also utilised the innovation of additive 3D printing methods to produce advanced technology part off modules. For the first time, this method also permits the production of a triangular shaped coolant outlet so that the coolant jet is precisely controlled to off the maximum cooling effect with minimum consumption and to ‘flood’ the furthest edge of the tool flank. These optimised cooling conditions also permit further potential optimisations, such as a reduction in insert width. Specific applications have shown that a part off tool of one millimetre less in terms of insert width with 20 machines and on 220 machine days means a reduction in annual costs in excess of £400,000.

Longer tool life due to less stress on the tool

With the ACS2 from ARNO, users feed coolant to places which were previously impossible. As this supply’s coolant under the chip, the chip breaks optimally and is flushed more easily out of the cutting zone. Chips are shorter and the tendency for built up edge insert conditions are greatly reduced. Measurements confirm that this coolant method reduces temperature by about half. As a result, the tool is exposed to much less stress and flank wear is considerably reduced. Instead of having to lower cutting and feed rates to protect the tool, rates can even be increased. Productivity rises since tool life is significantly longer. Users report that their tools last up to three times longer or at least twice as long. Fewer tool changes ultimately relieves the work burden on operating personnel. Not to mention significantly reduced machine down time

Maintaining inner cooling without tubes and interfering edges even during tool changes

Users need not do without direct cooling, even in turning operations. With the right tool holder, the integrated channels feed coolant close to the cutting zone. No complex adjustments are needed since the plug-and-play system always fits. Optionally, the manufacturer offers a VDI holding tool to match the tool holders and it feeds coolant to the holder without any pipe or hose connections.

Integrated cooling is even possible on sliding head lathes where tools must be frequently changed. Here, ARNO Werkzeuge recommends its AWL sliding heads tooling solution and the AFC quick-change tooling system. The AWL tool holder system (patent pending) offers bespoke solutions for a wide range of sliding head lathe manufacturers machine tools. The AFC quick change tool holders are mounted on a fixed stop and the required insert can be fitted or removed via two quick release clamping screws. Two separate cooling channels in the tool holder system can be opened or closed to permit tools with and without through tool cooling to be used in parallel. Here too, users report increases in tool life of over 25%.

Tools with through tool cooling raise productivity potential

It is almost always beneficial to use tools with through tool cooling wherever possible. And when you also find a tool manufacturer that understands the user’s manufacturing scenarios and has also given a lot of thought to the process, productivity receives a real boost. Precision without the hassle