Targeted high pressure coolant system from Horn benefits multi-spindle small component machining

The Graf system comprises a series of high pressure three-stage pumping units and tool bodies that provide coolant distribution to the point of use, through galleries within the toolholder, to maximise coolant benefit. Up to five tool stations can be attached via a switchable manifold, with easy on-tool connection via high pressure hoses using a 'clip-on' union. Paul Horn in Germany has participated in the joint development of holders to suit a range of Horn cutting inserts. In the case of the Horn Supermini, which has widespread application in machining small-scale internal features, for example, the outlet is aligned with the coolant hole passing through the insert, while blade-type tools (eg, grooving and part-off) have coolant emerging from multiple jets just behind the insert. Other external tools benefit from a nozzle that directs coolant onto the cutting edge. In so doing, the interface between the edge and the workpiece material is cooled and lubricated, while assisting chip formation, hindering the build-up of material on the edge and assisting the ejection of chippings from the work area. Graf's self-contained pumping units incorporate coolant tanks and filtration systems, and are capable of being retrofitted to the majority of existing CNC machines and respond to simple M-code commands to switch on/off. The effectiveness of the Graf system is highlighted in volume production of components where reduced need for tool changes can have major benefits. On a project requiring production of 8 million components for the electronics industry, it is reported that Graf through-tool coolant technology saved nearly €265,000, or just under 7% of overall production costs. This was due to a combination of the cycle time being reduced from 58 to 55 sec, an increase in insert life from 1,000 components to 6,500 components and associated insert cost and tool set-up time savings. In Germany, around 60% of Graf's sales are now derived from the system, says Mike Green, general manager of Horn Cutting Tools. He adds: "Applications such as parting-off and deep, narrow width grooving – as well as internal working – are obvious areas for this technology. Its basic flexibility means it need not be restricted to high volume production."