Fault diagnosis and analysis of aquatic extruded feed processing

Common fault diagnosis and analysis:

1.Uneven and irregular particles of finished products

ØThe clearance between screw and bushing is too large and uneven.

Ø Screw structure and its arrangement are unreasonable.

ØThe output is too small.

Ø Improper amount and position of water and steam adding.

Ø Formula factor (high fiber content, the proportion of main components is not conducive to uniform conditioning).

ØDie hole clogging.

ØUnreasonable design of extruder die hole shape or difference of mold hole diameter.

     2.Low expansion coefficient

ØInsufficient mechanical energy input

   Influence factor  ① Screw structure

                                     ② Screw and bushing are worn;

                                     ③ Spindle speed.

    Ways to change mechanical energy:

                                     ① Change the screw structure and arrangement;

                                     ② Change the spindle speed;

                                     ③ The internal pressure of the extrusion chamber can be changed by changing the feeding amount and the opening area of the template.

ØInsufficient heat input;

    Influencing factors: ① steam of the conditioner;

                                   ② Extrusion chamber steam;

                                   ③ The expansion cavity is heated.

Ø. Crushing fineness;

Ø Insufficient moisture;

Ø The formwork opening area is too large and the formwork hole shape design is unreasonable;

Ø. Influence of formula;

      ① Starch content;

      ② Fat: the fat content has no effect within 5%, and 7% is slightly smaller than 5%. Every 1% increase between 7 and 12% will increase 16 grams per liter of weight;

      ③ Coarse fiber: generally, the degree of expansion decreases with the increase of fiber addition, and too much fiber is not conducive to particle formation.

      ④ Protein: an important nutritional component in feed, which is not conducive to the expansion of materials, but it is conducive to improving the coagulability, water stability and elasticity of materials

     3.Poor particle stability, easy to crack 

Ø The extrusion strength of the extruder is not enough;

Ø. Formula (high fiber content, low protein and starch content, main raw materials are not conducive to improving the stability of particles);

ØPoor quality of quenching and tempering, insufficient water and steam addition;

    4. The product quality is unstable during production, and the expansion coefficient and color change

Ø Equipment:

    ① The screw structure and its rotating speed do not match;

    ② The screw bushing is worn;

    ③ Poor controllability of operation.

Ø The addition of steam and water is unstable;

ØThe feeding rate is unstable (the feeding silo, conditioner and bypass discharge are not smooth);

ØDifference of human operation (thermal energy and mechanical energy);

Ø Wrong ingredients.

    5. Material backflow

Ø Screw structure and assembly are unreasonable;

ØScrew wear

ØExcessive feeding amount

ØScrew, feed port and bypass port in feed area

ØBlocked by sticky material.