Cutting force measurement

With the measuring equipment available at the Institute of Welding Technology and Cutting Fabrication Processes, the individual components of the cutting force F can be precisely determined.

Knowledge of the magnitude and direction of the cutting force F and its components, the cutting force Fc, the feed force Fv and the passive force Fp, form a basis:

• for the construction of machine tools, i.e. for the design of frames, drives, tool systems, guides, etc. to meet the requirements;
• for defining cutting conditions in the work preparation,
• for estimating the workpiece accuracy achievable under certain conditions (deformation of workpiece and machine),
• to determine the processes taking place at the chip formation point and
• to explain wear mechanisms.

In addition, the magnitude of the cutting force is a measure of the machinability of a workpiece material, since higher forces generally occur when machining difficult-to-machine workpiece materials.

In order to determine the exact cutting force components, the measuring instruments must meet the following requirements:

• High stiffness, in order to exclude the influence of the measuring system on the machining process;
• High sensitivity, which enables accurate force measurement;
• High natural frequency, so that dynamic cutting force components can also be determined.

These requirements are best met by systems that work on a piezoelectric basis or with strain gauges. The Institute of Welding and Cutting Fabrication Technology has a Type 9263 three-component dynamometer from Kistler, see Figures 3 and 4. This measuring instrument is used exclusively to determine cutting forces during turning. Figure 1 shows a schematic diagram of the measuring chain for determining the cutting forces. For evaluation, the amplified measurement signals are recorded by a digital data acquisition system and recorded and graphically evaluated by a corresponding data acquisition software here DasyLab 5.0. The result of the cutting force determination is a measurement report in which the three determined components of the cutting force F, the cutting force Fc, the feed force Fv and the passive force Fp, are displayed as a function of time, see Figure 2.