Analysis on the causes of 12 kinds of extruded material quality defects
May 11, 2021
1. Uneven particle size, uneven length
The feed pellets are of different sizes and lengths, which not only affect the appearance of the feed, but also affect its palatability and the inconsistency of water resistance time, resulting in unnecessary waste. In addition, it will become an excuse for farmers to complain.
2. Many particles have pores
There are many pores in the particles, and the rough appearance 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 the floating time is long.
3. Deformation of particles is not round
The deformation of the particles may be due to the deformation of the die hole, or because the moisture is too high, it is squeezed and deformed during the conveying process when the mold is ejected. Therefore, it is best to use pneumatic conveying for the high-temperature extruded feed just out of the mold, which can not only quickly form a layer of gelatinous wrap on the surface of the pellets, reduce the crushing of the pellets, but also round the shape of the pellets. However, the particles are very heavy in moisture during pneumatic transportation and need to be dried as soon as possible. The particles are not far deformed, resulting in uneven particle size and affecting their palatability.
4. The particle hardness is not enough
Feed hardness is the resistance of feed to deformation caused by external pressure. Insufficient hardness of the feed will cause the feed to be deformed during transportation, thereby affecting the appearance of the feed. As a result, the feed will dissolve in the water before being eaten. It may also have a large amount of water, which makes it difficult to store the feed and is prone to mildew.
5. The particles have poor water resistance and poor viscoelasticity
The water resistance of feed refers to the anti-corrosion ability of feed in water, which is usually expressed by the rate of feed loss in water under specified conditions. Poor water resistance of feed will cause feed to dissolve in the water before it is eaten, causing unnecessary waste and polluting water quality. Poor viscoelasticity results in poor palatability of the feed.
6. The particle incision is not neat and oblique
The feed produced should be cut into neat-looking pellets, and irregular and deformed pellets will affect the appearance of the feed. It is generally caused by unreasonable adjustment of the incision and cutter, and it may also be caused by the large amount of feed.
7. The pellet expansion rate is not high
The feed is too hard and the water dissolution time is too long, which affects its palatability and digestibility. High content of lipid compounds will reduce swelling. When the fat content is 17-22%, the product will not expand too much or will not expand. A low pellet expansion rate will cause the feed to float in the water for a short time, easily sink to the bottom, and cause unnecessary waste.
8. The particles are submerged
The particles have sinking phenomenon, which may be caused by the low expansion coefficient and the excessive weight of the material. If some floating water particles sink into the water, it will cause unnecessary waste, and it will be difficult to observe fish eating.
9. The particles are big and small at the other end
The feed pellets are big at the end and small at the other end, which affects the appearance of the feed, easily causes feed breakage, increases the powdering rate, and reduces palatability.
10. The particles form a double-section concave shape
The double-section of the pellets is concave in shape, the feed is not uniformly expanded, and the ratio of water and steam is unreasonable, which usually occurs. Irregular particles not only affect the appearance and quality of the feed, but also cause more feed powder and affect its palatability.
11. Particles with tails
particles have tails, there are many reasons, mainly the problem of the cutter. Feed pellets have tails, which not only affects the appearance and quality of feed, but also causes more feed powder.
12. Peeling on the surface of the particles
Feed surface peeling is very easy to produce dust during transportation. Surface peeling may be related to the lack of moisture in the puffing, and may also be affected by the mold and cutter in the processing technology. It not only affects the appearance and quality of feed, but also causes more feed powder. Excessive addition of water will result in the material being too soft and easily deformed. Generally, 25-30% of the water should be added. Surface peeling will also affect the water resistance of the feed. Make farmers doubt the quality of the product.
