smartTOOL: Process monitoring directly at the point of action

Do you use modern machine tools in production processes, but cannot fully exploit their performance potential? The reason often lies in a lack of information on the cutting process and the tool condition. Specific process monitoring provides a solution!

Developments often focus on digitalization as an enabler when it comes to increasing productivity, economic efficiency and flexibility of modern manufacturing processes. The smartTOOL, an intelligent tool holder developed jointly by Fraunhofer IWU and Fraunhofer IIS as part of the Fraunhofer Cluster of Excellence Cognitive Internet Technologies, creates the required transparency by process monitoring close to the contact point. The highly sensitive data obtained forms the basis for comprehensive optimization and adaptive control of the machining process. In particular, further advantages of this monitoring solution lie in a new type of self-sufficient energy supply technology and in wireless data transmission.

Extensive measurement directly in the process

The smart tool holder is equipped with sensors for measuring vibrations, process forces and temperatures. This data is transferred via a wireless link to an evaluation unit with a graphical user interface. Here, specific evaluation algorithms are used to draw conclusions on the states of the process and the tool, and the machining result. In particular, the highest demands on the measurement sensitivity are placed on the detection of small changes in these aspects, e.g. caused by progressive tool wear or allowance and material fluctuations of the workpiece.  The digital monitoring system meets these requirements due to its direct proximity to the process. Critical process disturbances such as collisions, chatter or even tool breakage can be detected just as reliably.

Wide range of application scenarios

The high-performance data transmission enables the system to perform both real-time process monitoring and offline diagnostics. The recorded data initially form the basis for manual optimization of the machining process. In addition, the system can be coupled with a machine control system to implement adaptive process control, thus paving the way for cognitive production. For this purpose, significant characteristics are extracted from the sensor signals and transferred into decisions for actions via corresponding evaluation algorithms. The effects of these actions are also identified, enabling independent adjustment of the process parameters. Potential application scenarios may include, for example, NC path correction to compensate for elastic tool displacement, automated tool change at the end of tool life, or iterative feed rate reduction to eliminate dynamic instabilities.

No restrictions on automated production operation

The electrical energy required for permanent operation of the smartTOOL is generated primarily by an innovative energy harvesting solution. This is the first time this technology has been used in the production of machine tools. For this purpose, a simple component equipped with permanent magnets is assembled onto the spindle nose of the machine. The tool rotation generates electrical energy to supply the sensors, signal processing electronics and the radio transmitter. Neither the automatic tool change nor the available working space is restricted due to the small size of the magnetic holder. The 3D printed, easily adaptable assembly geometry additionally reduces the retrofitting effort to a minimum.

Flexible use on any machine

Almost all electronic components of the tool holder are located on a compact, universal segment between the fixture and the spindle interface. As a result, the latter two geometries are also largely freely selectable, allowing a wide range of application-specific combinations. Since the hardware is completely integrated within the designated standard segment, smartTOOL has no interfering contours. High static and dynamic stiffness is provided due to the optimized geometry. As a result, nothing stands in the way of using smartTOOL in a way comparable to conventional tool holders.