the groves on the roll body “pull” the product between the rolls, where the product is cracked. The force of the rolls does the cracking of the grain. The larger diameter rolls rely less on the corrugation due to the progressive deep trough created by large diameter rolls ( 24” and higher ). Smaller diameter rolls, especially 9” rely heavily on the corrugation due to the shallow through. For a dry product a sharp corrugation is recommended. For a high moisture or steam injected product a land is recommended, this will minimize the high moisture product from getting stuck to the roll and being built up. A corrugation of 6 – 24 GPI ( grooves per inch ) can only be done on Chillcast rolls. Hollow rolls will be done at ½” – ⅜” spacing.