In recent years, China's aquatic feed production has grown rapidly, and shrimp and precious special aquatic feeds have developed rapidly. Among these special aquafeeds, extruded pelletized pellets have become the main product form. Since the production lines of extruded Expanded Fish feed machine are mostly new in recent years, especially the control technology of the operating conditions of the extrusion extruder is not perfect, many domestic feed manufacturers are still groping for the processing technology and production characteristics of the expanded aquatic feed.
And the development stage, so the processing quality of the feed products produced by various manufacturers will have a big difference. Even the quality of the same variety of products produced by the same manufacturer in different batches may fluctuate significantly. There is no guarantee that the physical characteristics will be stable. After years of experience in production practice. It is believed that the bulking materials generally have the following defects during processing:
1) Uneven particle size and uneven length;
2) There are many pores in the particle;
3) particle deformation;
4) insufficient particle hardness;
5) The particle has poor water resistance and poor viscoelasticity;
6) The grain incision is not neat and oblique;
7) The granulation is not high;
8) The particles have submerged water;
9) The granules are big and small;
10) the particles form a double-cut concave shape;
11) The granules have a tail;
12) Peeling the surface of the particles.
After years of experience in production practice, the author summarizes some problems that often occur in the processing of expanded materials, and proposes corresponding solutions.
1. Uneven particle size and uneven length
Feed pellets vary in size and length, which not only affects the aesthetics of the feed, but also affects the inconsistency of palatability and water resistance time, resulting in unnecessary waste. In addition, it will also become an excuse for farmers to complain.
Cause of improvement Expanded Fish feed machine
The template opening is not reasonable.
The feeding is uneven, and the feeding mechanism is cleaned and adjusted for a long time. The arching device is added to make it evenly fed.
Uneven steam addition Adjust the steam addition point, multi-point, make it even
Uneven water addition Adjust the water addition point, multi-point, make it even
Uneven mixing Adjusting mixing uniformity
Blocking phenomenon
Mold hole guide opening difference is too large
2, more particles and pores
There are many stomata in the granules, and the rough surface not only affects the appearance of the feed, but also the feed is easily broken into powder during transportation, causing unnecessary waste. It is not easy to sink during the feeding process and has a long floating time.
Cause of improvement
The particle expansion coefficient is too large. Adjust the moisture and temperature as well as the pressure to reduce the expansion coefficient.
Low starch content in the formula, increased starch content
Ultra-fine thickness is coarser
Excessive moisture in the mold, reducing the moisture content of the mold
The surface of the mold is not smooth. Replace the mold.
3, the particle deformation is not round
The deformation of the particles may be due to deformation of the die holes or due to excessive moisture, which is squeezed and deformed during the conveying process. Therefore, it is better to use pneumatic conveying for the high-temperature puffed feed just emerging from the mold, so that not only the surface of the granule can be quickly formed into a layer of colloidal coating, the granules can be broken, and the shape of the granule can be rounded. However, during the pneumatic transportation, the moisture of the particles is very heavy and needs to be dried as soon as possible. The particle deformation is not far, resulting in uneven particle size, which affects its palatability.
Cause of improvement
Mould moisture is too high, reducing moisture during mold release
The outer diameter of the mold cover is too small.
The host is squeezed too much to reduce the host working pressure
The cutter speed is too high. Increase the number of blades and reduce the cutting speed.
Soft particles and hard objects are touched and squeezed multiple times, reducing the number of contact between soft particles and hard objects and the pressure.
Before the particles are not set, the scraper drying is used.
Excessive expansion rate, reduced expansion coefficient
Mold hole deformation Replace reasonable mold
4, the particle hardness is not enough
Feed hardness is the resistance of the feed to deformation caused by external pressure. Insufficient feed hardness can cause deformation of the feed during handling and thus affect the appearance of the feed. It causes the feed to dissolve in the water before it is eaten. It may also be a large amount of water. The feed is not easy to store and is prone to mildew.
Cause of improvement
The difference in moisture between the inside and outside of the pellet is large.
Rapid high temperature drying causes extended drying time
High granule moisture reduces particle moisture
Insufficient granular starch content, increased starch content in the formula
5, the particle water resistance is not good, poor viscoelasticity
The water resistance of the feed refers to the ability of the feed to resist corrosion in water, and is usually expressed as the loss rate of the feed in water under specified conditions. Poor water resistance of the feed can cause the feed to dissolve in the water before it is eaten, causing unnecessary waste and contaminating the water. Poor viscoelasticity results in poor palatability of the feed.
Cause of improvement
Excessive expansion rate reduces expansion coefficient
Low gluten content in flour, increased flour gluten content
Insufficient starch content Increases starch content in the formula
The drying temperature is too high, the surface is deformed, the cooked coke is lowered, the drying temperature is lowered, and the drying time is prolonged.
6, the grain incision is not neat, oblique mouth
The produced feed should be cut into neatly sized particles, irregular and deformed granules, affecting the appearance of the feed. Generally, the adjustment of the incision and the cutter is unreasonable, and it may be due to the large amount of material being fed.
Cause of improvement
The slit speed is too slow. Reduce the number of cutter blades and increase the cutter speed.
Feeding amount is too large, reducing feed amount
Unreasonable adjustment of the cutter, deformation of the cutter Adjust the cutter so that it fits close to the mold surface
7, the particle expansion rate is not high
The feed is too hard and the water is dissolved for too long, which affects its palatability and digestibility. High levels of lipid compounds reduce swelling, and when the fat content is between 17 and 22%, the product does not puff or expand. The low puffing rate of the particles will cause the feed to float in the water for a short period of time and easily sink into the bottom of the water, causing unnecessary waste.
Cause of improvement
The mold opening rate is too high. Replace the reasonable mold.
Low starch content in the material. Adjust the formula to increase the starch content.
The moisture in the mold is too low or too high. Adjust the injection amount of steam and water to make it reasonable.
Low feed rate, low productivity, increased feed speed
Low mold pressure, increased working pressure when the mold is released
Low mold temperature, high mold temperature
The material contains too much fat to reduce the fat content of the material.
8, the particles have submerged water
The particles have submerged water, which may be due to too low expansion coefficient and excessive material ratio. If some granular floating materials appear to be submerged, one is to cause unnecessary waste, and the other is that it is difficult to observe the situation of fish eating.
Cause of improvement
Low expansion coefficient, increased expansion coefficient
The material weight is too large. Adjust the formula, reduce the specific gravity of the material, and increase the expansion coefficient.
Low gluten content in the material Adjust the formula to increase gluten and starch content
When the material is out of the mold, the moisture is too low or too high. Adjust the moisture of the material during the mold release to make it reasonable.
Excessive die hole rate Replace the mold and use a mold with a reasonable opening ratio
The starch content is too low. Adjust the formula and increase the starch content.
The temperature is too low when the mold is released. Adjust the temperature at the time of the mold to make it reasonable.
9, the granules are big and big
The feed pellets are large and small, affecting the appearance of the feed, easily causing feed breakage, increasing the chalking rate and reducing the palatability.
Cause of improvement
The cutter speed is too slow, reducing the number of cutting blades and increasing the cutter speed.
Unreasonable adjustment of the cutter Adjust the cutter, not too tight, make it reasonable
The effective length of the mold is too long. Replace the mold.
10, the particles form a double-section concave
This is usually the case with a concave double-faceted granule, uneven feed puffing, and an unreasonable ratio of water to steam. Irregular granules not only affect the appearance and quality of the feed, but also cause more feed powder and affect its palatability.
Cause of improvement
Mould moisture is too low to improve the moisture content of the material when the mold is released
Unreasonable adjustment of water and steam Adjust the ratio of water to steam to make it reasonable
Unreasonable mold design
Low expansion rate, increased expansion coefficient
11, particles with tail
The granules have tails for a variety of reasons, mainly the problem of cutters. Feed pellets with tails not only affect the appearance and quality of the feed, but also lead to more feed powder.
Cause of improvement
The cutter is not well adjusted, and the cutting surface is not tightly attached to the mold surface to make it close to the mold surface.
The mold has a gap to create a trim or replace the mold
Excessive coarse fiber material, continuous cutting to increase the sifting effect, reduce the coarse fiber content or add a filter before the mold
There is debris on the cutting edge, causing the knife to leave the die surface and generate a shutdown to clean up the debris on the cutter.
The die surface is not flat, and the cutter jumps on the die surface during work to produce a trim or die change.
12, the surface of the particles peeling
The surface of the feed is very easy to produce dust during transportation. The surface peeling may be related to the lack of moisture in the expansion, and may also be affected by the mold and the cutter in the processing process. It not only affects the appearance and quality of the feed, but also leads to more feed powder. Excessive water addition, the formed material is too soft, easy to deform, generally should be added in 25 to 30% of moisture. Surface peeling also affects the water resistance of the feed. The farmers are skeptical about the quality of the products.
Cause of improvement
Unreasonable adjustment of the cutter
The cutter blade is not sharp. Replace the sharp cutter.
When the particles are out of the mold, the moisture is too low, and the moisture content of the material when the mold is discharged is increased.
The mold is not smooth, replace the mold
Iron filings at the die exit, trimming or replacing the mold
The temperature of the particles is too high when the mold is released