Avoiding "mixer” problems
Ribbon and auger mixers operate most efficiently if they are filled to 70 to 90% of capacity.
With paddle mixers, satisfactory mixing may be obtained at much lower levels of loading (25% of
capacity). However the application of fat and/or molasses to mixers that are not adequately
loaded may cause coating of the sides of the mixer and mixer bars, resulting in decreased mixer
efficiency and contamination. The mixer should not be overloaded. Overloading the mixer will
cause some of the feed to float above the mix and not blend properly. With paddle and ribbon
mixers the mixer bars should rise at least 12 cm above the level of the mix.
Improper mixing can also occur if the tolerances between the mixer bars and the sides of the
mixer are not set properly. Mixers are factory-set with an agitator clearance of .3 to .9 cm. If that
clearance increases to 1.3 cm, mixer efficiency will be impaired. Mixers should be visually
inspected periodically. Establish a set schedule for inspecting the mixer. Worn paddles and ribbons
should be replaced.
Do not deviate from proper mixing times. If possible have mixing time controlled by a timer.
Mixing time increases with the level of liquid feed added to the mix. This is because the mix
becomes more viscous, slowing down the flow of ingredients through the mix. This problem
accentuates when the level of molasses added to the mix exceeds the absorptive capacity of the
mix. Thus, the level of molasses employed in a diet formulation should be considered not only
with respect to relative cost of the molasses, but also with respect to practical mixing time and the
acceptable CV for the limiting micro ingredient in the mix.
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