World Grain - September 2021 - 70

MILLING OPERATIONS
Considerations for
future mill designs
Behavioral science-type approach could be used to optimize
equipment utilization, process flexibility and flour quality
by Jeff Gwirtz
The June 2021 issue of World Grain included an article, " The
Past, Present, and Future of Milling, " written by World Grain
Editor Arvin Donley. Milling industry leaders provided their
insights covering the history and future of the milling industry.
The purpose of this article is to offer some additional
thoughts relative to the future of mill design development in
the hope that a seed might be planted for future inquiry and
development of milling process design and management.
A wheat flour mill, whether it's in a laboratory mill, pilot
mill or commercial mill setting, is basically a fixed processing
entity at any one moment in time. Little can be altered with
respect to the flow to affect an immediate response in operating
efficiency or flour quality. Basically, we can alter the aggressiveness
of roll grinding, alter purifier settings to change
mill balance as well as material quantity and quality, and alter
flour stream selection to achieve specific grade requirements.
The available roll surface, sifter surface and purifier width
are fixed and cannot be changed without considerable effort
and expense. Transport equipment designs between processing
points are also generally fixed and designed to carry a
narrowly defined flow rate of product with equally narrow
material properties.
Long after the startup miller has left the site and detailed
operating instructions and guidance are long forgotten, replaced
by newly developed habits good or bad (not based on
sound facts or scientific method), mill efficiency, flour quality
or both begin to drift. The cumulative result generally has a
negative impact on mill economics resulting in a call to upper-level
technical support within the company or an outside
technical adviser.
Depending on familiarity with the original design flow and
modification history, the technical adviser leverages experience
and background to re-establish the intended mill flow
design and makes changes to realign with the available fixed
assets. Generally, the quicker issues are identified and corrections
made, the better.
Automation, remote process monitoring, and additional responsibilities
have distanced the mill operator from the pro70
cess.
Changes with wheat or mill stocks that impact processing
are not recognized as a potential cause but are obfuscated
by machine and/or processing system status changes. The focus
then is not understanding the cause for the system failure
but rather getting the system up and running.
Often this approach leads to solving the symptom (system
down), not the problem or what caused the system to go down.
The lack of data and proper analysis may result in, for example,
flow rate reduction to keep the system operating rather
than adjustment of roll gap to produce a product that would
work within system design parameters.
Wheat 'personalities'
Wheat is the material processed to produce the finished product
flour, yet wheat reduction, separation and intermediate
mill stocks are the least monitored and managed components
of the milling process. Current mill design and operation appears
to assume that wheat blends are inherently uniform and
that machine settings establish efficient capital utilization, efficiency,
and quality product. Experience suggests individual
varieties of wheat have their own " personality " or properties
that recalls the nature versus nurture debate surrounding personal
development.
The genetics may determine a significant proportion of inherent
traits. However, the environment, in the broadest sense
of the term, influences the expression of those traits. A given
wheat variety, therefore, is not the same when produced at various
locations under various conditions of rainfall, sunlight, soil
conditions, etc. In essence, wheat varieties and therefore blends
exhibit different personalities, properties and behaviors when
subjected to similar forces or milling processes. It is the behavior
of the wheat and monitoring of the wheat and mill stock
properties that may in the future have a greater impact on the
gradual reduction process design and management.
Milling wheat on a fixed laboratory milling system reveals
hard red winter wheat composite wheat sample personality
differences. At the very beginning of the milling process, the
feed rate is established by raising and lowering a feeder gate
September 2021 / World Grain / World-Grain.com
http://www.World-Grain.com
World Grain - September 2021

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