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SHIJIAZHUANG HONGDEFA MACHINERY :
China and Australia Wheat Flour Mill Technology
China and South Africa Maize Mill Technology
Australia office;Brazil agent;South Africa office,Zambia office,Rd Congo office
Shijiazhuang Hongdefa Machinery Co.,LTd is a professional manufacture of wheat
flour mill and maize mill,we provide high quality machine from 500kg/h to 50ton/h with
different design according to our client needs,with European technology,South Africa maize
process,China wheat process, roll out unique and innovative wheat flour mill and maize mill
plant.
The head office of Shijiazhuang Hongdefa Machinery Co.,Ltd is located 4hours
driving From Beijing,where we have approximately 100employees, a manufacturing facility of
3000square meters and 500 square meters of office space
Shijiazhuang Hon
gdefa Machinery have more than 30years experience in milling market.
The core technologies of our group are in the filed of wheat flour mill and maize
mill process engineering, with European technology, South Africa maize process,
China wheat process, roll out unique and innovative wheat flour and maize meal
processing line . It has the following features:
1.Roller Mills
NO.1 IN CHINA FOR ROLLER MILL
1)The partitioned paneling and swing-out feed module guarantee ideal
access to the feeding and grinding rolls. This makes residue-free
cleaning possible.
2) a pulse generator automatically adjust the feed material at the entrance door
3) bearing SKF
4) temperature monitor (option)
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2.Plansifter
NO.1 IN CHINA FOR PLANSIFTER
1) Material: High-strength alloy steel
2)up and down sifter circles with steel plate overall by bending
3)Transmission system using spring force component institutions
4)Sieve frames of wood coated with synthetic resin,without backwire
5)All the inside walls as well as the doors are provided with high-grade
insulation
6)Vertical and horizontal clamping system
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3.Dampener:Stainless steel.
4.Bucket elevator and conveyor with reducer
5.PIPE:stainless steel in milling section
6.Plant Control System :
PLC control system with CCTV surveillance system realize Seamless
integration
7.Electronic parts: Siemens/Schneider
8.Bearing:SKF/TWB
9.Reducer:flender/sumitomo /sew
10.Proportioning & Mixing,automatic computer control (wheat)
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Introduction of each function of cleaning machine
Bucket elevator: Bucket elevator is the vertical machine for lifting the raw material, and
the worm conveyor is the horizontal machine for carrying the material. As have too much
machines, we designed use vertical technical flow and horizontal flow in the factory to save
area and hight of the building.
High-performance belt:
Reinforcing material
made of synthetic
gumming canvas,warp is
low shrinkage polyester
filament , nylon filament
weft ; between the belt and the head wheel
add one layer durable base fabric; very good
for grain and good processing
The body bend with
one plate,no welding ,
long life
High-speed vibratory sieve: Vibrating sieve is a sifting machine with high speed.
The principle is when the sieve body are droved by two sides vibrating motors, maize flow into
the first sieve surface through feeding entrance, large impurity on the upper sieve is discharged
to the hopper. Another material come into the second sieve surface for continual sift. On this
surface, the maize and small impurity are separated each
other. Finally lighter impurity is discharged by the
suction pipes. This machine has much speciality such as
high capacity, without jaming and so on. The function is
the sieve remove all impurities from maize to reduce dust
and impurity to pollute workshop as much as it can. And
ensure rear working line with good running. Meanwhile
to avoid jaming into the slip of screw conveyor and exit
of damper bin.
Main Area No welding Quality sheet
Vibration smooth uniform feeding
Special Drawer design,easily to maintain Galvanized Bolt Tight
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Magnetic separator: Avoiding the metal material running a high speed into the machine to
make a spark under beating and friction situation.
Gravity classifier destoner: According to different gravity between maize and same size
stones, and air dynamics, adopt destone and sieve performance and movement parameter, and
air current speed, the destoner to classificate the raw material. The maize and stones moving on
the sieve with different direction, made the stones are separated from wheat.
■ Higher efficiency destoner,shutter sieve structure
■ Easy operation, compact structure.
■ For different materials,destoner sieve can adjust between 10-14 degree
■ External fan, whole machine sealing , no dust outside, to achieve the desired environmental
requirements. Reciprocating swing,splices using rubber bearings, vibration low, low noise.
■ Adopt self-aligning bearing with locking device, so that the mechanical character more
stable
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Damper: Specially for maize
Computer control moisture
Bi-Direction screw,prevent free water
Intensive intermixing
Stainless steel screw leaf and outside
No Leaking
Degerminator:Degerminator is designed to scrub the maize skin from the maize
kernel,and to dislodge the maize germ from its cavity,with the minimum reduction in size
of the broke fragments.
American Technology minimum reduction in the size of the broke fragments
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Roller Mill: The mill the most important one machine of whole processing line, is mainly for
grinding. To break maize and bran’s structure, and spearate the maize husk and the embryo
from endosperm by grinding.
The partitioned paneling and swing-out
feed module guarantee ideal access to
the feeding and grinding rolls. This makes
residue-free
A pulse generator automatically adjust
the feed material at the entrance door
Bearing SKF
Sensor Omron
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Plansifter can classify the material that from break, reduction and scratch systems and sifting
the flour.
Material: High-strength alloy steel
Up and down sifter circles with steel plate overall by bending
Transmission system using spring force component institutions
Sieve frames of wood coated with synthetic resin,shape no change
All the inside walls as well as the doors are provided with high-grade insulation
Vertical and horizontal clamping system
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Gravity Table: which use the gravity is select the granual which is same size with the
grits,to improve final products extraction
This machine is the use of germ and corn granules
specific gravity and different suspension velocity air
stream by means of physical action up through the corn
grits and corn germ gap prompted particle sizing, as
directed in the inclination to mention the role of the
embryo reciprocating sieve, corn granules to the
discharge end of the movement. Floating on top of the
germ under its own weight, to the embryo population
movements, thereby germ separated from corn residue
Turbo sifter is a perfect sifting equipment,combined vibrating shifting and centrifugal
sifting,the screen hole not block,and more suitable for sticky material,widely using sifting
the bran and flour
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Scale:Online scale and packing scale
1.Online auto cumulative weight;
2.High-precision on-line flow control;
3.Frequency (batch) weight control;
4.With MODBUS communication interface with computer networking, computer centralized
management control;
5.According to customer needs, can have the print function.
6.Feeding and support is stainless ste
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PIPE:in milling section is stainless steel
AIR SYSTEM
Screw air compressor
Belt tensioning convenient, simple replacement of the belt structure,
completely eliminate mechanical resonance
According to acoustic principles, enclosures closed, eliminating noise
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MAIZE MILLING DESIGN INSTRUCTION
COMPOSITION OF MAIZE PRODUCTS
CLASS OF
MAIZE
PRODUCT
FAT CONTENT
BY MASS %
FIBRE
CONTENT BY
MASS %
FINENESS BY MASS
MIN MAX MIN MAX
1. Samp - 1.5 - 0.8
Not more than 5% shall be whole grain and not
more than 5% shall pass through a 2.36mm sieve.
2. Maize Rice - 1.5 - 0.8
At least 90% shall pass through a 4.0mm and not
more than 5% shall pass through a 1.18mm sieve.
3. Maize Grit - 1.5 - 0.8
At least 90% shall pass through a 1.4mm sieve and
less than 90% shall pass through a 300 micrometer
sieve.
4. Maize Flour -
Less
than 2.0
- 0.8
At least 90% shall pass through a 300 micrometer
sieve.
5. Super Maize
Meal
-
Less
than 2.0
- 0.8
At least 90% shall pass through a 1.4mm sieve and
less than 90% shall pass through a 300 micrometer
sieve.
6. Special
Maize Meal
2.0
Less
than 4.0
- 1.2 At least 90% shall pass through a 1.14mm sieve.
7. Sifted Maize
Meal
3.0
Less
than 4.0
- 1.2 At least 90% shall pass through a 1.14mm sieve.
8. Unsifted
Maize Meal
3.5
Less
than 4.5
More
than
1.2
2.5 At least 90% shall pass through a 1.14mm sieve.
9. No.1 Straight
Run Maize
Meal
3.7 - 1.8 2.5 At least 90% shall pass through a 2.36mm sieve.
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10.No.2
Straight Run
Maize Meal
3.7 -
More
than
2.5
6.5 At least 90% shall pass through a 2.36 mm sieve.
11. Unsifted
Crushed Maize
3.2 1 1 2.5
Not more than 5% shall be whole grain,and not
more than 40% shall pass through a 2.36mm sieve
12. Sifted
Crushed Maize
1.5 - - 2.0
Not more than 5% shall be whole grain,and not
more than 5% shall pass through a 1.18mm sieve
13. Fine
Crushed Maize
1.5 - - 2.0
At least 90% shall pass through a 2.36mm sieve
and not more than 10% shall pass through a 1.0
micrometer sieve.
14. Maize
Germ Meal
10.0 - - - -
15.Fine Maize
Bran
-
Less
than
10.0
More
than
6.5
17.0
At least 90% shall pass through a 2.0mm sieve and
at least 50% shall pass through a 1.4 micrometer
sieve.
16. Coarse
Maize Bran
-
Less
than
10.0
More
than
6.5
17.0 -
17. Industrial
Grade Maize
Product
- - - - -
Though not strictly applicabe to products many of the above fat and fibre contents are still
recommend in most company based quality matrix.
OUTLINE OF THE MAIZE MILLING PROCESS
1. PREPARATION OF THE MAIZE FOR THE MILLING PROCESS
Before the milling process proper can commence the maize must be suitably prepared. During this
operation all impurities and foreign matter are removed, and finally the maize is conditioned by allowing a
controlled quantity of water to penetrate the bran before the grain is ready for milling.
2. THE MILLING PROCESS
The process of manufacturing the products involves three fundamental sub-processes. The first
of these, physically detaches the three components of the maize kernel from each other. with as little dilution
or mixing as possible.second, sorts and classifies the detached particles into specific groups and the last, sizes
and reduces the particles to the required granularity. The three components are then recombined as
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necessary depending on the type of finished product
Required The aim of the process then, is to detach the bran and germ from the maize
kernels with a minimum disintegration of either the endosperm or the bran/germ casing. The pure endosperm
is then gradually reduced in size to form products of different granularity, ranging from the relatively large
pieces of camp to the very Fine maize flour. Some of the bran and germ are also ground down in the
process and a certain amount combined with the ground endosperm to meet the
specifications of the coarser meals such as sifted and unsifted maize meal.
2.1 Detaching the bran and germ from the endosperm
This part of the process is carried out 6y treating the conditioned maize on either a degerminator or a roller
mill.
2.1.1 The degerming process
The action of the degerminator is designed to 'scrub' the bran skin from the maize kernel and to dislodge
the germ from its cavity, with the minimum reduction in size of the broken fragments.in the machine the
maize is subjected to a rubbing, tumbling action by a revolving cone with a very coarse surface which
peels the bran from the endosperm and frees the germ. At the same time the machine effects a rough
Separation of the broken endospem pieces from the fragments of bran and Germ by means of a perforated
screen. Because of varying maize characteristics,And imperfections in machine design, a certain amount of
breakage and Imperfect separation is unavoidable and much be rectified later in the process.
2.1.2The roller mill process
For the purpose of detaching the bran from the endosperm, very coarsely fluted rolls are used, The shearing
action provided by the flute spiral and roller speed Differential breaks open the whole maize kernels and
detaches much of the endosperm from the bran and germ.
However, this does not provide as much clean endosperm as the degerminator and a good deal of work
remains to he done later in the process, but the roller mill does have an advantage in that the action does not
pulverise the germ and bran to the same extent as the degerminator.
2.2 Sorting and classifying the broken particles
This is the second part of the milling process and involves the use of several different types of sieving
machines as well as aspirators.
2.2.1The drum type sifter or Le Coq sifter
Because of its sturdy construction and high capacity, this type of sieving machine is often used to separate the
germ meal fraction from the broken endosperm particles produced by the degerminators. The separation
effected is only a rough one but it greatly facilitates the later sieving operations on the plansifters.
2.2.2 Plansifter
The modern plansifter has been developed into a highly efficient machine capable of sorting a single feed
into six or seen different ranges of particle size. This is done by using several different mesh aperture sizes
which effect the separations mainly as a result of difference in particle size as wail as variance in density and
shape. The action of the plansifter causes endosperm particles, with
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their inherently higher density and comparatively spherical shape, to work their way down to the lower layers,
while the germ and bran particles remain in the upper layers. The size of the particle In relation to that of
the aperture of the sieve, then ultimately determines whether the particle will pass through the aperture or not.
Using these principles the plansifter classifies the broken particles of maize so that they may he processed
more efficiently on the Machinery which follows.
2.2.3 The Concentrator or gravity table
This machine continues the classification of the particles by utilising a combination of air currents and an
oscillating deck to sort out particles according to differences in density. Since endosperm is appreciably
denser than germ, which in turn is denser than bran, a single stream, consisting of a mixture of these particles,
can be classified into as many as four groups of varying purity Prom pure endosperm at the one extreme to
pure bran at the other, with varying combinations of Composite particles in between.
2.2.4 The Aspirator
Throughout the milling process one of the Chief aims is to Isolate bran and germ Particles from clean
endosperm in order to prevent contamination of the finished products.
The aspirator is particularly useful in this regard as it sorts out the particles by Using their
disparity in air resistance. The shape of a particle plays a significant Part in determining its
behaviour in an air current and since bran (and, to a lesser extent, germ) in addition to having a
lower density, tends to be flake-shape,it is ideal for separation by aspiration.
2.3 Reducing the particle size and sifting out the products
Final reduction in size of the cleaned and graded maize particles is always carried out by roller
mills. Finely fluted rolls are used and the accuracy with which the Severity of the grind can be
set makes the roller mill ideal for this purpose. The plansifter is also ideally suited for the
purpose of sizing the ground particles according to the required granulation. Particle sizes in the
finished products range from 4000 microns in the case of maize rice down to 300 microns for
maize flour and all of these can be accommodated by the range of sieves available in the
modern plansifter.
2.4 Summary of the process
The entire milling process in constituted by combining the sub-processes referred to above into
groups of series and parallel operations. A simple example is shown in Diagram 1. Each
group performs basically the same operation, the only difference being that the particle size
gradually diminishes as the process proceeds step by step from raw material to finished product.
In general terms the machinery flow sequence is: degerminators and roller mills- plansifters
一 aspirators 一 concentrators 一 rollermills. The reason for this sequence can be readily
appreciated by considering the nature of the particles before and after each treatment.
To begin with, a wide range of different sized particles is created during treatment by the
degerminators and roller mills. To facilitate separation and subsequent processing, the particles
must first be classified into groups, each having a narrow range of particle size. This is why the
plansifters always follow the roller mills.
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Once the particles have been classified into size groups, advantage can be taken in differences
in nature of the particles which make up the kernel components. The bran,being significantly
different from either germ or endosperm in air resistance, is readily separated first by means
of aspirators. With the bran removed, germ can be separated from the endosperm on the
concentrators or gravity tables, according to density differences.
Endosperm particles,now comparatively free from Both bran and germ and the unavoidable
fragments cut up during the roller mill process,can then be suitably sized on another roller mill
In order to meet granularity specifications.
3.THE DEGERMING PROCESS
3.1 The degerming process originated in America where it was developed as the quickest and
easiest way to remove the germ and outer bran covering from the maize kernel. In the USA,
maize is seen as a valuable source of vegetable oil and the farmers are encouraged to cultivate
varieties of yellow maize with large germ components and high oil content. In this milling
process, the main objective is to recover as much of this valuable portion of the maize kernel as
possible, and so, in effect, the germ fraction is considered to be the prime product, while
the endosperm and bran are treated as the by-product and disposed of mainly as cattle feed.
Some of the endosperm is recovered in the form of samp or grits and used in the production of
breakfast cereals or snack foods。But of prime importance is the germ oil from which then, so
many types of food are obtained. In the American process,the emphasis is on the production of
as much good quality germ as possible and the incidental breaking up of the endosperm is
considered to be of minor importance.
Perhaps because of this, the design of the degerminator is robust,with few refinements and its
action in separating the bran from the endosperm and dislodging the germ is extremely rough.
In our country on the other hand, the aim of the degerming process is to remove the bran from
the maize kernel and dislodge the germ from its cavity with the minimum damage to the
endosperm, bran and germ. This facilitates the sorting process which follows degerming and
is designed to separate the endosperm, bran and germ from each other and to minimise
possible contamination of the clean endosperm fraction with the oil from the germ. Further
processing on the mill converts the endosperm into various finished products such as samp,
grits or meal which, in this case, are the prime products, while the combined germ and
bran fraction, which remains a valuable source of oil, constitute the by-product.
The type of degerming used in the South African milling process varies to some extent and
may take the form of
1. a full degerming of the maize to produce clean samp (damp degerming);
2. a type of skinning procedure where only a partial removal of the germ and
bran takes place;
3 or 'partial damp' degerming which differs considerably from the other two.
3.2. DAMP DEGERMING PROCESS FOR SAMP WITH HORIZITAL TYPE DEGERMERS
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This is a 'damp' degerming process which involves the use of steam or water to rise the moisture content of
the outer bran layers of the maize kernels before they enter the degerminator. A 'HORIZITAL type'
degerminator is used, based on concept, and the purpose is to produce a high proportion of large
endosperm pieces or samp, from which all the bran and germ has been removed, with a minimum amount of
damage to any of the three components.
3.2.1 Condition of the maize
In order to achieve the best results, it is vitally important that the maize feeding the samp degerminator
should be in optimum condition. The type of maize will affect results and it is best to use a hard, dent type
if a good yield of samp is to be obtained. Soft local varieties are unsuitable as they break up too
easily and produce large quantities of fine endosperm particles which mix irretrievably withthe bran and germ
fragments. This problem was experienced in recent years by mills throughout the country when drought
conditions forced the millers to rely on soft, yellow maize imported from America and Argentina.
Most of the white dent varieties of maize produced under normal conditions in South Africa are
suitable for use in the samping process but, in addition to cultivar,
the following points should also be noted in selecting the maize:
1. The endosperm must be free of cracks or stress lines which are usually
caused by negligent drying techniques on the part of the producer;
2. the kernels must be whole and preferably as evenly sized as possible;
3. The maize must be clean and free from loose impurities; and
4. The natural moisture content should be low enough so that it is possible to
Add the required amount of water in the conditioning process.
If the maize selected conforms as nearly as possible to the above requirements, it should be possible to
deliver the maize to the degerminators in the best possible condition for samping.
In order to produce the best results, the final condition of the maize should be such that:
1. The endosperm remains as hard as possible and has the maximum resistance to attrition;
2. the bran is as tough as possible. This includes the black tip cap which must be removed intact, with
the bran;
3. the germ is firm and pliable; and
4. the adhesion between the bran and endosperm is at its lowest.
The methods used to achieve correct conditioning have been covered in Module 2but, in general, they involve
controlled moisture addition in the form of water or steam and carefully set lying times, in order to allow
limited penetration of the maize kernel. There is a divergence of opinion on moisture addition limits as well
as optimum penetration times but these will vary depending on local conditions and the type of maize used.
A moisture addition of 6% to 8% and lying time of 20 minutes should result in clean separation
of the maize components by the degerminator under normal condition.
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3.2.2 Other factors affecting degerming
3. 2.2.1 The feed
The capability of a degerminator to deliver good samp is directly affected by the
consistency of the feed rate. The maize should enter the machine at the rate recommended by the
manufacturer, which is generally between two and four tons per hour, and should not be allowed to vary.
The rate is normally controlled by volumetric feeders but these must be checked regularly as foreign material
very often accumulates inside the compartments and so volume flow is reduced over a period even though the
setting has not altered.
When a degerminator is underfed, not only is the power being wasted but also the breakage will
increase because the particles remain inside the degerminator for longer than necessary. Conversely,
if the machine is over-fed, the maize will not be properly degermed and the quality of the samp will be
poor. Electronically controlled variable speed measurers are now being used in the modern maize mill,
their function is to reduce feed automatically in the event of an overload condition on the main motor
caused by a build-up of feed in the degerminator. The feed rate does not vary under normal conditions.
The regular flow of maize to the machine may also be disrupted by a build-up of metal fragments on the
magnet which is usually installed in the feed spout. Besides obstructing the feed, this also reduces the
effectiveness of the magnetic protection and could result in damage to the rotor or casing.
3.2.2.2 The rotor cone adjustment
The pertormance of the degerminator may be controlled to a certain extent by altering the severity
of the treatment while the machine is in operation.'The main adjustment is effected by a leer, which moves
the position of the rotor cone in relation to the stationary casing. The correct setting is determined in
association with the tension on the discharge gate and is a matter of establishing the correct
balance between the side and end clearances in order to avid under- or over degerming. Once the
optimum position has been determined, farther adjustments should not be necessary exce the rotor or
casing.
3.2.2.3 The discharge gate adjustment
Any adjustment to the tension on the discharge gate (or tailsgate) has an immediate effect on
performance as this virtually controls the duration, and hence, the severity of the treatment. The tension
must provide just sufficient resistance to the maize flowing through the degerminator to enable degerming
to take place without undue damage to the particles.
3.2.2.4 Condition of the degerminator parts
Worn working surfaces inside the degerminator are bound to result in sub-standard results
and efficient operation depends on a regular maintenanceprogramme.
a. Worn scroll sections at the feed end will retard the maize at this point and
upset the flow of product through the machine.
b. Worn nodules will not be able to detach the germ and bran and will
produce a high proportion of finely ground germ meal.
c. Worn perforations will upset the balance between throughs and overtails
while holed screens will allow undegermed particles to fall through.
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3.2.2.5 Germ meal
The germ meal referred to here and elsewhere in the chapter consists of a mixture of finely
ground germ, bran and endosperm fragments created by the abrasive action of the degerminator. This
fraction passes through the holes in the perforated plates and constitutes the degerminatar 'throughs'. It
contains most of the germ and bran and nearly all of the water added in the conditioningprocess. The
moisture content must he reduced as quickly as possible by means of artificial drying to prevent deterioration
of the meal.
When a degerminator is operating efficiently, the fragmented endosperm content of the germ
meal is reduced to a minimum. this is indicated by a low percentage germ meal figure showing that most
of the endosperm is overtailing the degerminator in the of large pieces of samp.Too much tine endosperm in
the germ meal is a sing of inefficiency and may be the result of soft maize, poor conditioning, incorrect
machine setting or worn working surfaces.
3.2.3 Advantang of the damp degerming process
the principal advantage of the process is that it yields a high percentage of large. fully degermed samp from
which a variety of other grade prodcts such as maize rice and brewers grits can be produced. Supe maize
meal and other meals produced from the samp are also of excellent colour and quality.
4.Break and reduction roll systems
This chapter deals with the further treatment of the relatively pure endosperm pieces which
were produced by the degerming system as described in the previous item.This is the last part
of the actual milling process where most of the finished products are finally produced.
The function is to reduce the endosperm to intermediate size particles which are divided into
several different grades which facilitates more accurate grinding on te reduction rolls.In setting
these rolls it should be borne in mind that the aim is to size the particles for further processing
and while a small amount of meal will inevitably be produced, this is not the main objective.the
severity of the grind at this stage should never be sufficient to produce maize flour
5.Sifting system
6.Balance system
7.Packing Machine