The grinding of solid samples is essential to ensure precise analysis. It is important that the grinding leads to the homogeneity and desired fineness of the sample.
The type of mill to be used depends on the properties of the substance and the quantity of the sample. For example, brittle materials are ground with a beater, fibrous materials with a blade, and hard/brittle materials are ground with a special hard metal cutter.
Small sample quantities are generally ground with a batch mill. Here, the samples are ground very smoothly and a particle size spectrum of the ground material can be expected. Larger quantities can be ground with an inline mill. Here, the sample passes through a sieve, which leads to the ground material achieving a defined particle size.
Problems can arise when soft and tough materials such as rubber or plastics have to be ground. The problem can be solved through the embrittlement of the sample with dry ice or liquid nitrogen. The sample can then be ground without difficulty.