​How Does a Grain Cleaning Machine Work

What is a Grain Cleaning Machine?

Grain Machine is a machine used for cleaning and sorting Grain. The Grain is sorted for thickness on screens with elongated holes. The screens which are usually flat and have less frequently cylindrical revolving round holes are used to sort for width. Brushes, beaters, and other devices are used to remove particles stuck in the screens. Length separators are used to separate seeds by length and fans to separate them by aerodynamic properties. Gravity and electromagnetic seed cleaners are used for separating by surface condition and shape. The pneumatic picking table separators are also used to separate by specific weight. A distinction is made between simple and complex grain cleaning machines. A simple machine has one, two or more working elements, and a complex machine has several, usually including fans, screens and cylinder sorters.

The operation of the grain cleaning machine is based on differences in the width, thickness, and length of the grain, and in the aerodynamic properties, surface condition, shape, and specific weight.

Grain-cleaning machines can be mobile or stationary. Mobile machines are used on the threshing floor; stationary machines are used at cleaning and drying stations and at plants with flow technology.

In the agriculture of the (Union of Soviet Socialist Republics) USSR, grain is cleaned and sorted at grain-cleaning station and sorting station using OS-4.5A and OVP-0 mobile units and OVS-10B and SVU-5 stationary machines.

The cleaning and drying stations also use winnowers, length separators, electromagnetic machines, sorting machines, and dryers.

These grain machines consist of ultra-low speed, no broken elevators, vertical air screen, cyclone dedusting system, large proportion platform, vibrating and grading screen. it can remove dust, chaff, shell and other light impurities. It can also remove the blighted seed, budding seed, damaged seed (by insect), rotter seed, deteriorated seed, moldy seed, non-viable seed, seed with black powder sick. After the large and small impurities have been removed the finished product can be divided into big, medium and small particles.

Traditional methods

The simplest cleaning method, known as winnowing, consists of tossing the grain into the air and letting the wind carry off the lightest impurities.

Although widespread in farming circles, this cleaning method does not eliminate the heavier impurities (gravel, foreign grains, earth, etc.).

Cleaning devices

If the desired product is to be completely free of impurities and suitable for long-term storage, appropriate cleaning devices must be used such as, winnowers, pre-cleaners and cleaner-separators.


These machines, some models of which may reach an output of one ton per hour, can significantly contributeto improving product quality and marketing, especially in production areas.

Sometimes operated by hand but more often motorized, winnowers are relatively simple machines that consist mainly of a hopper to receive the grain, a fan and a set of sieves.

The grain unloaded into the hoppers first has its lightest impurities removed by running it through a current of air produced by a fan.

Then, the set of sieves completes the cleaning of the grain at the same time it is sorted according to size.


These motor-driven devices are generally used to pre-clean grain that has been harvested when moist, before it goes to the artificial dryer.

There are several models of pre-cleaner:

  • the circular pre-cleaner, in which impurities are eliminated principally by suction (output of about 150 quintals an hour);
  • the drum pre-cleaner, in which the heaviest impurities are eliminated by passing the grain through the meshes of a drum, and the lightest are eliminated by suction (output of about 10 to 50 tonnes an hour);
  • the clodder, in which the bulkiest impurities are eliminated by means of a coarse, vibrating sieve.


These machines, whose large outputs can be as much as 20 tonnes an hour, are certainly the most effective instruments for cleaning grain, and all storage centres should be equipped with them.

Cleaner-separators are motor-driven and consist mainly of a reception hopper, a fan and set of vibrating sieves; they clean grain by repeated suction of the lightest impurities, followed by siftings of the grain.

The set of sieves, composed of a coarse sieve (clodder) for the bulkiest impurities and a fine sieve (sifter) for the finest impurities, must be chosen with care, taking account of the shape and size of the grains to be cleaned.

The usual recommendation is a set of sieves with oblong perforations for long grains and for round grains, a clodder with round perforations and a sifter with oblong perforations.

For optimal use of the machine, it is also important to take care in making thevarious adjustments (to the flow of grain, the suction, and possibly to the speed of vibration of the sieves).

Application and function

This machine can replace gravity separators, reduce the load of gravity tables and increase production further. It is widely used in corn, wheat, rice, sorghum, job’s tears, vegetable seeds, beans and other commercial grain and economic crops, remove light skin, lint and dust from materials, remove large and small impurities in materials, remove the impurities such as empty shells, moldy, dried grains and immature grains in the materials.

It can also be used for processing wheat, rice, corn, soybean, sorghum and other commodity grains, productivity can reach 20t/h, and can remove more than 90% kinds of light impurities from grain. Most of these machines complete wind selection, gravity selection, screening and grading, which can save energy and reduce consumption and labor.

Environmental cyclone duster system and without a lot of dust leakage. It can be equipped with an elevator, screw conveyor and belt conveyor.

The front sieve can remove small impurities, which can reduce the load of the gravity table and blockage of small particles. The machine can also remove kinds of light and small impurities, which improves the selection of proportion greatly.

Principle and Applicability

The Air Screen Cleaner with Gravity Table mainly includes elevator, bulk grain box, air screen, screen box, gravity table, dust removal system and other structures.

Processing: After feeding, the material is lifted to the bulk grain tank by the elevator and enters the air screen evenly through the bulk grain function. The dust and light impurities with small proportions in the material are separated by the dust removal system. The material enters the screen box and the big and small impurities are removed through the hole screen. After screening, the material enters the gravity table, and the heavy light impurities such as mildew and empty shell are removed through the interaction of wind force and vibration. The material enters the back half screen for secondary classification screening to improve the filtering accuracy.

This equipment is mainly used for the pre-cleaning, removing dust, whisker, empty shell, orange stem, mildew particles and other impurities. It is characterized by large output, energy conservation and environmental protection, and high cost performance.

Air cleaning section, loading and unloading conveyors, a self-propulsion mechanism, and three 10.8 kW electric motors to drive the working elements and the propulsion mechanism. With the machine moving along the bale at a speed of 0.1 - 0.3m/min the loading conveyor feeds grain into the receiving chamber from which it enters the aspiration ducts and is acted upon by the air current. Light extraneous matter is separated from the grain and blown off the machine through a pipe. The grain enters the sieve boot for cleaning coarse and fine impurities. The cleaned grain is removed from the machine by an auger and a conveyor. The impurities are removed by a pneumatic conveyor. The machine's output is 10 - 20 tons per hour. The OVV- 220 machine, in which impurities are removed by an air current is also used on farms. Complex foreign made grain cleaning machines have simple design and are equipped with fan, screens and learnt separators.

Technical Precedence

The first step is to remove impurity by the gravity table, which can effectively improve the purity of the materials on the gravity separator, reduce the screening pressure on the gravity table, and improve the output and purity.

It has mature air separation devices that collect dust and light impurities effectively and also clean with environmental protection.

It has multi-functions, such as air selection, screening and specific gravity, reducing labor, site saving, energy saving and consumption reduction.

Most grain cleaners come with a double vibration motor, high frequency, low amplitude, self vibration balance, etc., more stable.

It also has gravity table vibration and eccentric drive vibration, independent vibration source, high stability and Ultra-low speed non broken elevator to minimize broken loss.

Effective cleaning of all types of crop seeds

In cleaning effectively Seed-calibrating by the specific weight, and getting healthy high-class sowing material must be considered;

Picking out the most viable and productive grains from the general pile should not be toiled with.

Ensure you take puny, crushed, pest-damaged and sick seed away to the waste.

Ensure cleaning and calibrating of all types of cereals and products of their production, and also any types of bulks (granite crumbs, crushed stones, sawdust, etc.).

Getting ecologically pure production by minimization of using plant protectors, selecting grain with high protein content, and rising classiness of cash grain.

Getting inexpensive and high-quality sowing material, and also preparing excellent cash and bread grain. Crop capacity rose up to 40%.

Convenience in work with any initial material without essential restrictions in impurity and humidity of the initial material (in 95% cases).

Simplicity in operating and maintenance, after-sales service, warranty, longevity, broad model row from 4 to 150 TPH.

Some of the controls described above are aimed mainly at establishing the condition of the grain at the time of its reception at a storage centre. These controls permit not only a better definition of the market value of the product but also an identification of the type and urgency of treatments which the grain should undergo before storage, marketing or further processing.

That is why at Gz industrial supplieswe give out the best grain cleaning machine for all our esteemed clients so as to ensure maximum and productive service in functionality of the product.

For more info on how grain cleaning machines work or selecting the best grain cleaning machine kindly Contact Us at Gz industrial supplies.

Nov 09, 2020 Joseph Umoh

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