WOOD PULP AND PAPER 39 



process, that is, wood is cut to 2-ft. lengths and is either peeled in the 

 woods or rossed or barked at the mill. Wood, however, is more carefully 

 selected for this process than for ground wood pulp. 



Chipping. 



As the blocks of 2-ft. bolts come from the wood room they are passed 

 on a conveyor to the chippers. The chipperman makes a final inspection 

 of each bolt before it goes into the machine, and the large blocks which 

 escaped the splitter and the undesirable species are sent back. Any 

 blocks having any bark attached are sent to the helper who removes the 

 bark with a hatchet. 



Pnotograph by Pusey-Jones Co. 



FIG. 5. Wood chipper used to reduce the bolts of wood to chips for use in the manufacture 



of chemical pulp. 



The chipper is very similar to the rossing machine except that it is 

 much heavier in construction. It consists of a solid steel wheel with 

 knives inserted, the only openings being at these points to allow the chips 

 to pass through. This is covered with a heavy metal case to keep the 

 chips from flying. The blocks are fed into the machine and against this 

 wheel so that they strike the knives nearly perpendicular to the grain. 

 The revolution of the wheel causes the knife to make a sliding cut and a 

 slice is taken off the end of the block. As the wheel revolves at about 

 2000 R.P.M. this cutting is done so fast that the piece cut off is broken 

 into small chips. These chips fall down into a pit below the machine 

 and are carried to the screen by a cable and belt conveyor. Chips are 

 generally about j in. in length and TF to 3^ of an in. or more in thickness. 



