Precision separation on a kilogram scale is very important in many industries, particularly the pharmaceutical industry where 10–20kg of a product can cost thousands of dollars. 450mm diameter sieves are a very effective way of size separation on such a scale because they give very sharp cuts at the specified sieve size. Unless the sieves are accurately calibrated, however, a repeatable cut point cannot be guaranteed. Even though the sieves used may be nominally the same size, some large differences in absolute mesh size have been observed in the past.