2. Grinding — Generally, very little labor is needed for the grind- 

 ing of ingredients, except to set the proper conveyors and gates, adjust 

 the feeder control, change a screen, and clean the magnets occasionally. 



Corn and alfalfa pellets, the two ingredients that require grinding 

 before mixing, are in bulk form in all the model mills except A where 

 alfalfa pellets are in bags. In this mill the operator must move, open, 

 and dump the bagged pellets into a sink located above the hammermill. 



A vi?ual check of the grinding equipment when operating is requir- 

 ed only in Mills A, A' and B. The other mills have remote indicating 

 devices to eliminate the periodic checks at the machines so no labor 

 requirements are shown in Table 3 for them. Responsibility for per- 

 forming this operation is generally given to the receiving or mixing stage 

 personnel. 



3. Mixing — The labor requirements for mixing depend upon the 

 kind of mixer, materials-handling equipment, and the degree of auto- 

 mation used to control the process. Three equipment combinations are 

 considered: (1) the vertical mixer with weigh buggies for weighing and 

 moving bulk ingredients, (2) the horizontal mixer with feeder screws, 

 weigh hopper, surge bin, and semi-automatic controls, and (3) the same 

 equipment combination as (2) but with automatic controls. 



The first equipment combination requires a substantial amount of 

 labor since the ingredients are handled manually. Buggies are loaded 

 with the required amount of each bulk ingredient, moved, and dumped 

 into the empty vertical mixer. Bagged ingredients are moved from the 

 warehouse, opened, weighed out, and dumped into the mixer sink. As 

 the batch is mixed, the buggies are reloaded. The mixer operator adds 

 any pre-mixes and controls the mix time. This equipment combination 

 is used in model Mills A, A' and B and the man-equivalents vary from 

 1.0 to 2.6. 



The second equipment combination requires a two-man crew. The 

 mixer operator controls the conveyors moving ingredients to the weigh 

 hopper, the weighing, mix time, and the gates in the weigh hopper and 

 mixer from a control panel. An assistant weighs out and adds bagged in- 

 gredients to each batch and performs other minor tasks such as cleaning 

 up around the mixer sink. This equipment combination is utilized in 

 model Mills B' and C. 



The third equipment combination is almost completely automated. 

 The material handling, weighing, mix time, operation of gates, and num- 

 ber of batches are automatically controlled. The mixer operator sets the 

 proper controls for each formulation run, adds premixes, and oversees 

 the operation. With a motor control panel for operating equipment in 

 other manufacturing stages, the mixer operator coordinates the manufac- 

 turing stages in the mill. This type of system is used in Mills D, E, and F. 



The automatic system has two characteristics not found in the other 

 systems : (1) only one operator is required over a relatively wide range 

 of mixer capacities, and (2) all batches of a given formulation are prac- 

 tically identical because possibilities of human error are largely elimin- 

 ated. 



4. Pelleting and Crumbling — The labor requirements for the 

 pelleting stage are essentially those needed for overseeing the operation. 



13 



