In close cooperation with the Kistler Group (a leader in dynamic measurement technology for measuring pressure, force, torque and acceleration), the German tooling company Paul Horn GmbH, which has a UK subsidiary in Ringwood, has further developed its solution for real-time monitoring of tools used in turning applications.

The Piezo Tool System (PTS) consists of a force sensor that is ‘precisely’ built into the turning tool and provides information on the condition of the tool during machining. It can measure forces from just a few Newtons upwards and has a standard sampling rate of 10,000Hz, making it possible to measure even the smallest cutting forces.

This capability allows a machine operator to identify defective workpiece materials or grades, or even a tool breakage immediately, resulting in minimum waste and ‘an outstanding level of quality’. Furthermore, the user can extend the service life of the tools used.

Horn offers the sensor-monitored tool-holder as a square-shank turning tool-holder, a gang tool unit for Citizen Swiss-type lathes, and a base holder for Index multi-spindle lathes and for the Supermini tool system. Additional interfaces for other machine manufacturers are in development.

The PTS is especially suitable for turning operations, for which alternative measurement methods — such as monitoring the drive power of the main spindle motor — are not practical as they cannot detect minute deviations. Furthermore, measuring ‘structure-borne’ sound cannot deliver consistently satisfactory results when machining small workpieces, and visual monitoring has to be ruled out due to the use of coolants and the high rotational speeds of the machining process.

The PTS solution, which is compatible with selected standard turning tool-holders from Horn, does not require any intervention in the CNC system, can be used on any machine and only requires a small amount of space. Converting standard holders to PTS holders is easy and does not require any further modifications to the machine.

The tool carriers offer ‘outstanding stability’ despite the measurement technology that is built in; and the PTS gang unit is used in exactly the same way as a standard gang unit, allowing all standard tools to be installed.

The processes of changing tools and making adjustments are no different from those performed on a standard gang unit. The standard base holder 968 for Index multi-spindle lathes can be replaced directly with the PTS base holder 968.

The holder system allows all Horn type 842 cartridges to be used. Tool change, cartridge exchange and adjustment of the centre height are identical to those of the standard tool.