Most seeds have a tough oil bearing cellular structure which has to be ruptured or weakened prior to cooking and extraction. Milling rolls and flaking rolls are used for this duty. The former can be arranged in vertically mounted stands with the material guided down through the contra-rotating rolls, the material comes under increasing pressure as it presses down the stand.

Care should always be taken to give a roll stand an even feed over the full face otherwise uneven wear will occur and give poor results.

The same is true for flakers which are essentially a pair of horizontal smooth surface rolls of large diameter rotating towards each other with a slight speed differential to produce flakes of around 0.3 to 0.5mm. Modern machines use hydraulic cylinders to control the thickness and can handle capacities up to 400 tons per day.