A machine that cuts wooden logs to chips as a prelude to the pulping process in papermaking. Following debarking, logs must first be converted into uniformly-sized chips (or other suitable form) as an aid to chemical digestion of the wood. A multiple-knife disk-type chipper consists of knives that rotate rapidly on a steel disk. Logs are fed end-first into the knives, which cut them into chips. A screening of the chips ensures that they are all of a uniform size, and foreign, non-wood material and contaminants are removed. The chips are then ready to be sent to the digester. (See also Pulping.)
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