World Grain - June 2006 - 66

FEATURE

OF MILLING TECHNOLOGY

Part III
Editor's note: This is the third article in a three-part series on
the history of milling technology. The first two installments
were published in the April and May issues of World Grain.

What began as a laborious hand
operation in ancient times evolved
into a highly-mechanized process
by Bryan McGee

he history of milling technology has been one of continuous innovation in pursuit of technical and commercial
improvement. Significant changes have occurred from
time to time, but even between technological advances, seldom
has there been stagnation. Cereal milling and cereal science remain full of promise.
Our generation has witnessed the impact of electronics,
which permeate every aspect of this and other industries. We
are now seeing the effect of the Internet, which has accelerated
the diffusion of ideas and stimulates the worldwide acceptance
of new ideas.
This article focuses primarily on the evolution of wheat milling technology during the last half of the 20th century and beyond, which has been marked by the phenomenal advances in
electronic control and instrumentation, raising productivity to
unprecedented levels. Better control devices and systems, advances in cereal breeding as well as methods and materials of
construction have raised quality standards and throughputs of
machinery as never before. The use of computer-aided design
(CAD) and computer numerical control (CNC) machine tools
have accelerated these trends.
However, there have also been some processing innovations
that have been of at least equal importance.
PNEUMATIC CONVEYING
During the 1940s, Daverio, a Switzerland-based company,
was credited with building the first full pneumatic conveying
68

system using negative pressure to suck the intermediate stocks
from the lower levels of the process - mainly from roller mills
- to the top of the building. The materials would then fall by
gravity to the next machine in the system.
This concept, which dispensed with the traditional cumbersome bucket elevators and horizontal screw conveyors, offered
huge advantages that were gradually realized over succeeding
years by all of the major milling engineering firms.
The use of pneumatic systems provided much greater flexibility in plant layout and improvements in hygiene and sanitation through the removal of these intrinsically difficult-to-clean
conveyors and elevators.
The conveying air also was used to cool the stocks in transit.
Removing heat from the process gave an important benefit in
allowing much higher roll loadings without the necessity for
complex water cooling. It also maintained a negative pressure
within the equipment, thus preventing the emission of dust
within the plant. A shortage of high-grade timber after World
War II accelerated the adoption of metal tubing for mill spouting, which also helped to remove potential areas for insect infestation.
ENTOLETER
Connecticut, U.S.-based Safety Car Heating and Lighting
Company, after carrying out some mixing trials in the 1950s,
discovered by chance that the passing of insect infested mill
stocks through a twin disc rotor with pins, which they were usJune 2006 / World Grain / www.World-Grain.com

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World Grain - June 2006

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