Milling White Paper

In order to achieve the desired properties for any material, the manufacturing process steps must be optimised to achieve the desired microstructure in a cost-effective way. For ceramics, particle size distribution of precursor powders can, for example, have a significant effect on powder flow (and thus the ability to fill a mould), reactivity (response to heat and other component chemicals) and final grain size (which has a myriad of effects on the material performance). Particle size distribution can be controlled through the judicious use of milling.

Milling can broadly be summarised as breaking down a material powder into progressively smaller particles within a closed vessel using repeated small-scale collisions with each other, the vessel walls and often additional milling media. Milling is not the same as ‘crushing’ and ‘grinding’, which are earlier stages in powder processing. ‘Crushing’ tends to imply coarse products, ‘grinding’ fine products and ‘milling’ the application of a particular process to produce a defined product.

It is more common for material suppliers/processors to carry out crushing/grinding stages, so downstream manufacturers are more focused on the final milling, which is the subject of this paper.

This white paper discusses some of the milling options that are available, their advantages and disadvantages, as well as focusing on how the milling process can help to control key characteristics to optimise the properties of end products in manufacturing processes.