Progress Report Series No. 57 August, 1955
AGRICULTURAL EXPERIMENT STATION
of The Alabama Polytechnic institute, Auburn, Ala.
E. V. SMITI-, Director
RESULTS of PERFORMANCE TESTS of
A SMALL FARM MIXER GRINDER*
J. L. BUTT, Associate Agricultural Engineer**
Reductions in feed costs result in greater mar-
gins of profit for the 
poultry or livestock producer.
Lt is known also that with normal conditions
home-grown grains are the cheapest source of
livestock concentraLes. In cases where feed grains
are to be purchased ratl er than grown at home,
it is possible to save on grain costs by buying dur-
ing the harvest season when prices are lowest,
and by storing the grain on the farm. This is es-
pecially true in years of high production. In order
:o take advantage of low-cost grains, whether
home-grown or purchased, it is desirable to have
grinding and mixing facilities available on the
farm to process the grain into a usable feed mix-
tui e.
Home-mixed feeds have not been used by cer-
tain farmers, especially poultrymen, because of
Ehe rather tedious job of mixing the ingredients
in the right proportions to provide a balanced ra-
tion. To meet the requirements for these farmers,
a farm mixer should (1) proportion, (2) mix, and
k3) grind the feed with a minimum of supervi-
sion, labor, and power. A machine embodying
most of these characteristics has been placed re-
cently on the market. This paper reports results
obtained to date with one such machine that meets
these requirements.
This report describes feed grinding and mixing
tests conducted during the spring of 1955. The
mixer-grinder chosen for testing was character-
ized by the following features: (1) It requires only
a 2-hp. electric motor for power which makes its
'.se possible on most Alabama farms; (2) it will
automatically proportion, mix, and grind as many
* Funds for this experiment were made available by
the Alabama Power Company.
**The author acknowledges the assistance of C. D.
Squiers, associate animal husbandman, and G. R. In-
gram, associate poultry husbandman, in these tests.
as four ingredients simultaneously without super-
vision; (3) it is equipped with a time switch that
will automatically turn the machine off when
a predetermined quantity of feed is ground; (4) it
is a relatively inexpensive unit.
Description of Test Machine
The mixer-grinder (Figure 1) consists of a
small hammermill mounted on the shaft of a 3450
r.p.m., 2-hp. single-phase electric motor and a
proportioning unit. Grain and concentrate are
delivered from storage bins to four separate feed
hoppers at the top of the mill. These hoppers
iti~ ~
it
Figure 1
are equipped with feed augers for conveying the
grain or concentrate into a mixing hopper from
which it flows into the hamnmermill. The amount
of rotation of the feed augers can be controlled by
a series of dials, which in turn regulate the rate
and amount of each ingredient flowing into the
mixing hopper. By selecting the proper ratio on
the dials, the desired feed mixture may be ob-
tained.
Since the augers deliver ingredients on a vol-
ume basis, it is necessary to convert the weights
of the ingredients desired into equivalent volumes
by dividing by the weights per bushel. Tables
with information on weight per bushel for various
crops and formulas showing sample calculations
are supplied by the manufacturer. In these tests
the weight per bushel was determined for each
ingredient. A time switch on the machine permits
the operator to set the mill to operate without at-
tention for the lengh of time necessary to provide
an adequate supply of feed. Motor overload pro-
tertion and safety pins are built into the ma-
chine. An ammeter mounted on the machine in-
dicates when the motor is loaded, thus enabling
the operator to fully' utilize the power ,init.
/
/
~1 I
/
/
'U -
Figure 2
Procedure
The mixer-grinder was placed on a platform
underneath four holding bins and above a feed
cart (Figure 2). In order to determine how ac-
curately the machine proportions, the holding
bins were filled witti weighed amounts of each
ingredient, the dials were set, and the machine
run until one of the hoppers was empty. The
amounts of ingredients in the other hoppers
were weighed and recorded. Data taken for each
test run were (1) quantity of feed processed, (2)
time of operation, (3) electricity (in Kw.-hr.) re-
quired, (4) distribution of the electrical load, and
(5) weights of the remaining ingredients not
ground during the test run. The actual ingredients
comprising the mixture were determined by sub-
tracting the weights of ingredients remaining in
the hoppers from the amounts originally placed
in them. These data arc expressed on a percent-
age basis in Tables 1, 2, 3, 4, and 5.
Poultry Mixture Tests
A series of tests was conducted for grinding
poultry feeds of three different protein levels, 14,
16 and 18 per cent. The desired protein level was
calculated on the assumption that corn contained
9 per cent and concentrate 20 per cept pmitein. by
weight. The corn and concentrate were then
weighed to give the desired protein level and plac-
ed in the hoppers of the grinder. The dial set-
tings were calculated and the mixture ground
until one feed hopper ran empty. The amount
TABLE 1. SUMMARY, TESTS OF GRINDING SHELLED
CORN AND CONCENTRATE FOR AN 18 PER CENT
PROTEIN POULTR3Y RATION
Dial settings,
hopper
1 23 4
Percentage by weight
of ingredients in ration
Calculated Actual
Corn Cone. Corn Conc.
Rate
lb.
per
hr.
Kw.
hr.
per
100
23 24 24 11* 18.18 81.82 17.8 82.2 2,086
20 9*
20 10*
13
7* -
6*
6*
17
18-
17
18.18
18.18
18.18
18.18
18.18
18.18
18.18
18.18
18.18
18.18
81.82
81.82
81.82
81.82
81.82
81.82
81.82
81.82
81.82
81.82
1.826
1,636
763
1,248
1,200
1,224
1,268
94G
933
933
18.18 81.82 18.53 81.47 1,277.9 .180
Indicates hopper containing corn.
'WAR
TABLE 2. SUMMARY, TESTS OF GRINDING SHELLED
CORN AND CONCENTRATE FOR A 16 PER CENT
PROTEIN POULTRY RATION
Dial settings, Percentage by weight Kw.
hopper of ingredients in ration 
Rate hr.
Calculated Actual per 100
1 2 3 4 Corn Conc. Corn Conc. hr lb.
22* 19 19 19 36.36 63.64 39.1 60.9 1,714 .178
23 25 9* 10* 36.36 63.64 37.2 62.8 1,725 .176
18* 25 25 36.36 63.64 39.7 60.3 1,184 .203
17* 24 24 - 36.36 63.64 36.4 63.6 1,234 .222
17* 24 24 36.36 63.64 36.9 63.1 1,209 .233
19* 25 25 36.36 63.64 38.7 61.3 1,077 .236
18* 25 25 36.36 63.64 38.3 61.7 1,191 .232
17* 25 25 36.36 63.64 37.4 62.6 1,222 .228
36.36 63.64 37.96 62.04 1,319.5.214
* Indicates hopper containing corn.
TABLE 3. SUMMARY, TESTS OF GRINDING SHELLED
CORN AND CONCENTRATE FOR A 14 PER CENT
PROTEIN POULTRY RATION
Dial settings, Percentage by weight Kw.
hopper of ingredients in ration Rate hr.
lb. per
Calculated 
Actual per 
100
1 2 3 4 Corn 
Conc. Corn Conc. 
hr. lb.
19* 19* 24 24 54.55 45.45 56.3 43.7 1,654 .213
24 19* 24 19* 54.55 45.45 54.5 45.5 1,123 .246
24 19* 24 19* 54.55 45.45 54.4 45.6 1,090 .240
15 23* 15 - 54.55 45.45 53.9 46.1 936 .278
15 23* 15 - 54.55 45.45 53.3 46.7 969 .316
10* 25 10* - 54.55 45.45 57.5 42.5 730 .298
9* 25 9* - 54.55 45.45 55.5 44.5 858 .283
8* 25 8* - 54.55 45.45 53.7 46.3 997 .270
54.55 45.45 54.89 45.11 1,044.6.268
* Indicates hopper containing corn.
of corn and concentrate remaining in the other
hoppers was weighed and the percentage of corn
and concentrate actually in the mixture was cal-
culated to compare with the desired percentages.
These data are given in Tables 1, 2, and 3. It
should be noted that some dial combinations
caused greater variations from the desired per-
centages of each ingredient than others. Once a
dial setting is determined as satisfactory, in ac-
tual practice it would be used until a different
mixture or different ingredients were to be run.
Swine Ration Tests
Tests involving two swine rations were con-
ducted. Oats, corn, and concentrate were pro-
cessed for one feed, while corn and concentrate
were used in the other. Procedure was the same
as that described for poultry rations; the data are
presented in Tables 4 and 5.
TABLE 4. SUMMARY, TESTS OF GRINDING SHELLED
CORN AND CONCENTRATE FOR A SWINE RATION
Dial settings, Percentage by weight Kw.
hopper of ingredients 
in ration Rate hr.
lb. per
Calculated 
Actual 
per 
100
1 2 3 4 
Corn Conc. Corn Conc. 
hr. lb.
23 24 14* - 79 21 79.3 20.7 814 .419
23 24 14* 79 21 79.0 21.0 915 .390
23 24 14* - 79 21 78.7 21.3 927 .367
23 24 14* - 79 21 78.6 21.4 912 .382
23 24 15* - 79 21 77.6 22.4 734 .410
24 24 14* - 79 21 79.9 20.1 1,292 .288
23 14* 24 - 79 21 79.9 20.1 666 .410
23 14* 24 - 79 21 79.0 21.0 558 .428
24 14* 24 - 79 21 79.6 20.4 692 .504
24 14* 25 - 79 21 79.5 20.5 772 .375
24 15* 25 - 79 21 79.5 20.5 781 .354
24 15* 25 - 79 21 79.0 21.0 785 .366
18 12* 19 - 79 21 77.8 22.2 546 .410
19 12* 20 - 79 21 79.2 20.8 562 .428
79 21 79.04 20.96 782.6 .395
* Indicates hopper containing concentrate.
TABLE 5. SUMMARY, TESTS OF GRINDING OATS, SHELLED CORN AND CONCENTRATE FOR A SWINE RATION
Dial settings, Percentage by weight of Kw.
hopper ingredients in ration Rate hr.
lb. per
1 2 3 4 Desired 
Actual per 100
Corn Oats Con. Corn Oats Conc. hr. lb.
211 7' 13 13 57 30 13 57.6 28.9 13.5 627 .482
18 15' 5 - 57 30 13 58.7 27.7 13.6 546 .581
18 161 52 - 57 30 13 57.7 29.1 13.2 539 .570
18 161 5 - 57 30 13 57.3 28.9 13.8 546 .557
18' 62 22 57 30 13 57.9 28.5 13.6 468 .522
18' 62 22 57 30 13 57.6 30.2 12.2 445 .663
211 6
"  
25 57 30 13 57.0 30.0 13.0 428 .555
211 6' 25 57 30 13 57.6 29.8 12.6 419 .573
161 20 5' - 57 30 13 57.5 28.8 13.7 517 .546
171 21 5' - 57 30 13 57.0 30.0 13.0 533 .543
17' 21 5 - 57 30 13 57.1 30.3 12.6 503 .579
17' 21 5' - 57 30 13 57.1 29.7 13.2 474 .560
21 191 62 - 57 30 13 58.5 28.2 13.3 509 .531
22 20' 62 57 30 13 58.1 28.7 13.2 527 .554
22 211 62 - 57 30 13 57.6 28.7 13.7 - .566
23 22' 6 - 57 30 13 57.0 30.0 13.0 480 .543
Mean 57 30 13 57.58 29.22 13.20 504.1 .558
SIndicates hopper containing oats.
SIndicates hopper containing concentrate.
Discussion of Results
Shelled corn, grain sorghum, oats, wheat, feed
meals, and concentrates were handled by the ma-
chine. The mill does not grind ear corn or for-
age crops without preliminary processing. The
mill proportioned, mixed, and ground feeds with-
out further attention after it had been started by
the operator. Once a satisfactory series of dial
settings was determined, the amount of the dif-
ferent ingredients in a mixture usually varied
less than 1 percentage point (Table 4, lines 1, 2,
3, and 4.) The farmer will probably have to
make two or three test runs to adjust his mill to
the correct proportions if the accuracy just des-
cribed is required. This may be done by running
100-pound lots of the mixture through the ma-
chine and adjusting the dial settings until all
hoppers empty at the same time.
When the higher dial settings were used, the
capacity wgs higher. The amount of electricity
used varied with the amount of grinding required
by the mixture (compare Table 1 having 18.2 per
cent corn with Tables 2 and 3 containing 36.4 and
54.5 per cent corn to be ground, respectively).
Summary
The test mill was found to proportion mix and
grind feeds for poultry or swine rations in one
operation. Once a suitable series of dial settings
was obtained the mill consistently metered the
various ingredients into the feed mixture within
1 percentage point of desired quantities. The
hammermill produced a satisfactory grind. Elec-
trical consumption ranged between 0.151 and
0.663 kw.-hr. per 100 pounds of feed depending
upon the dial settings and amount of grinding re-
quired for the mixture. Machine capacity varied
from 419 to 2,086 pounds per hour, again depend-
ing upon the dial settings and mixture ingredients.
There was some separation of the feed mixture
upon falling into the feed cart, which was reduc-
ed by adding collecting hoppers beneath the ham-
mermill and reducing the distance the feed drop-
ped into the feed cart.