Responsible Use of Kinematic Models: Correspondence on "Navigating Ball Mill Specifications for Theory-to-Practice...

In their recent article, Jafter et al. present "refined" kinematic models for planetary and mixer mills. While the improvement of such models is a valuable pursuit, we find that aspects of the presentation and application of these models raise concerns. The authors modify an existing planetary mill model, yet the altered equations offer no clear advantage and obscure the underlying milling dynamics. The mixer mill model is similar to known models, but includes additional parameters, such as an empirical scaling factor, that lack theoretical justification. Furthermore, the models are applied using estimated or hypothetical values for important milling parameters, contributing to overestimations of the energy metrics. Rather than dismissing the use of kinematic models, we emphasize the importance of applying them with care by using accurate input parameters, being aware of their assumptions and limitations, and interpreting their outputs in the context of what the energy metrics represent (maximum energies released from impacts). When employed responsibly, kinematic models can provide valuable insight, and thus, we encourage a more rigorous and transparent application of these models to support the broader goal of reproducibility in mechanochemistry.