How the Roller
Mills Changed the Milling Industry
Milling was founded on sound information and tradition passed on from
one generation to another. This is the way it was both in England and when
it came to this country. The millstone was the miller's symbol of his art
and his industry, and they were reluctant to accept roller mills in place
of the millstone. One of the practices that was involved in milling was
that metal should never come into contact with ground meal. Grinding grain
with something other than stone, was un-heard-of. The millstones were a
familiar and trusted device. When roller mills first appeared, the traditional
millers never believed that the roller mills could ever replace the millstone
as the prime flour milling device.
A natural conflict resulted between the millstone and the roller mill, there
was also a conflict between the water wheel and the turbine. Many millers
held a belief that the water wheel was superior to the turbine. There were
arguments as to which system would work better together, the millstone or
When millstone grinding began to be threatened by the roller mills, the
miller tried to improve the dressing of the millstone. They tried to increase
the number of quarters on the millstone. This they discovered could not
make a noticeable improvement over the old style of dressing. They tried
to increase the number of furrows but it did not improve the product output.
Even with improvements, the millstone still was slower grinding than roller
The roller mill became a good alternative to the progressive millers who
wanted a better milling process. They wanted to improve the quality and
quantity of their flour product. This led to the primary attraction of the
use of roller mills. In replacing the millstone with roller mills, the miller
gave up the time consuming process of dressing millstones.
The early roller mills could not do as well of a job in flouring middlings
as millstones. It was not until roller mills were improved that their use
grew. The first use of roller mills was to break up the grain. Then a pair
of millstones would be used to regrind the particles into flour. Eventually
this practice became obsolete with the addition of other rollers replacing
the millstones. The miller had to learn new skills. He learned that by increasing
the number of breaks he could extract almost all the bran and produce superfine
In the larger milling operations they started to bleach the white flour.
It was soon determined that any remaining particles of bran and germ were
made more noticeable.
A large-scale milling operation was built as an automatic mill. In these
automatic mills there were improvements in the mill's bolters. At this time
came the introduction of the purifier and wheat cleaning was greatly improved.
Almost every impurity was removed from the grain before it was ground. The
germ which effects the shelf life of flour could be scraped off after the
first break. The roller mill would break the grain to produce floury middlings.
The floury middlings could be bolted and purified to remove some of the
bran. Then the middlings would be reground using a slower grinding speed
and there would be a more extensive bolting to extract as much flour as
The roller mills increased the amount of flour as well as speed up the milling
process. Roller mills could produce more marketable flour than millstone
Roller mills used more belt pulley drives with metal shafting and less
large gears. The newer roller mills had better roller mountings, using belt
drive. These rollers could run faster than the earlier gear operated roller
mills. The first noticeable difference was that the belt drive roller mills
made considerably less noise. The roller mills had corrugated cast-iron
rollers with better bearings and feed control. The differentials, on each
roller pair, control the rotation. The non-touching rollers, each ran at
a different speed. If both rollers ran at the same speed the grain would
travel though with little or no treatment done to it. The slower roller
tends to hold the grain while the faster roller shears open the kernel of
the grain. This process produces break flour mixed with bran. Increasing
the number of breaks and bolts, the total extraction of flour would remain
the same as from millstones., The use of gradual reduction with rollers,
the percentage of best-grade flours could be increased, while the poor-grade
flour would remain the same or be reduced.
The main argument against rollers was the expense of the roller mills themselves.
The roller mills became more useful with other gradual reduction equipment
being added to the expense such as increasing the number of bolting reels,
purifiers and aspirators. Roller milling became more adapted to the larger
milling enterprises, the roller mills caused a great demand of capital,
which the larger mills could provide to purchase new equipment.
The roller mills are used primarily in the large merchant mill. They were
never really identified with the term roller mill. Many of the more successful
milling operations converted from millstones to rollers. As the millers
installed roller mills, their mills were no longer referred to as grist
mills, but they were to be known as roller mills for generations to come.
The Leeper Roller Mill, Germania Roller Mills, Juniata Roller Mills are
Roller mills became identified with the less nutritious whiter flour, while
other mills still continued to use millstones to make their stone-ground
flour. The nutritional value of the white flour was evident in that so much
of the nutritional value was removed from the flour that insects, that infested
stone ground flour, could not sustain themselves in the new varieties of
the white flour. The insect infestation, which plagued the milling operations
was reduced, but it produced a less nutritional flour.
It was not until the 1940's that the American milling operations started
to enrich flour. Flour became enriched with thiamine, niacin, riboflavin
and iron. Whole wheat flour does not need to be enriched. Enrichment may
have been a great step forward but why was it needed in the first place?
Note: A version of this article by T. R. Hazen appeared in OLD MILL
NEWS, January 1980, Vol. VIII, No. 1, Whole Number 30, page 6.
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