A sensory tool holder is an inline tooling adapter that is capable of measuring three different dynamic responses within the tool – these being the bending moment, the tension and the torsion. With applications to both milling and turning operations, a sensory tool holder can continually collect data during a given operation and wirelessly transmits this data to a nearby laptop. This data can be visualised in real-time and can also be subsequently, exported allowing for post-processing analysis.
Figure 1 - Sensory Tool Holder Set Up for Turning
Plots of the measurements vs time can be obtained and can be directly correlated to the wear experienced on a tool. For example, a large jump in the bending moment can relate to the failure in a cutting edge. Similarly, developing polar plots of bending moments can show the distribution of the wear in an X-Y reference frame. In a milling operation, this can be directly related to the wear on individual teeth, demonstrating that a tool may wear unevenly. Based on this data, the machining strategy can be updated in order to extend the tool life by balancing the wear evenly, which ultimately can increase the productivity of the cycle.
Figure 2 - Example of Collected Data Showing a Sharp Increase in Measurements at a Failure Point
In addition to developing an understanding of a single machining operation, when combined with an appropriate Design of Experiment, it is possible to construct a Tool Life Model based on the results obtained from each independent run. This allows for a standard process of evaluating and comparing the performance at various cutting conditions. In addition to this, it also acts as a base point for comparing tools between different manufacturers. This tool life model can ultimately be applied to any future operation allowing for the life of the tool to be predicted before any work is carried out, which can potentially prevent tool failures from damaging the workpiece.
Sensory tool holders also allow for in-process analysis and optimisation, whereby the process is analysed and compared with existing machining strategies. This allows for key areas of the process to be identified, including unfavourable cutting conditions, productivity and the influence due to different materials.
State of the Art/Maturity
The sensory tool holder is in its early stages of adoption with its primary use currently in a research and development environment. It is evident that there are significant benefits to be achieved through the use of the tool in improving productivity alongside reducing the waste caused by broken tools.
Practical applications for Machining
• Real-time data analysis allowing for operators to be aware if a tool may break.
• Ability to predict the tool life in order to allow operators to make a tool change before causing damage to the part.
• Ability to improve productivity by minimising the wear experienced by a tool.
• Ability to develop an understanding of how different tools can perform and then be able to predict the performance given a change in cutting parameters.