
398 Process Techniques for Engineering High-Performance Materials
the formulation and then starts the blending cycle. The formulation expert
assumes that the blending operators will carefully meter out the exact mea-
sure of each component to the limit of the accuracy of their measurement
tools. Toward that end, the blending station is equipped with precision
scales, which are frequently calibrated.
In the real world, human factors intervene. One operator is concerned
about keeping the work area clean and orderly. Before adding the rubber, the
operator brushes any dust in the hopper down into the mixer. When measur-
ing the additive, a small a