1. modification process

 

modificationPFA GranulesThe main production equipment is twin-screw extruder,

 

The common production process is: ingredients, mixing, extrusion, k-pull, cooling, all grains and packaging.

 

The quality problems of modified PFA particles can be divided into appearance defects and unqualified performance, and the appearance defects are discussed here. Appearance defects are mostly related to the production process, raw material quality, production equipment, production environment and other factors. Common defects include long strips, even grains, black spots, discoloration, poor vacuum, iron filings, poor plasticization, carbonization, etc. Starting from the production process, this paper analyzes the common quality problems of modified PFA particles and puts forward countermeasures.

 

2. common defects

 

1. Long strip

 

A length greater than 2 times that of a normal particle is regarded as a long strip.

 

The main causes are the start-up pull strip or broken strip, the direction of the material strip is not straight, the cutter of the pelletizer is worn or has a gap, etc.

 

Main solutions:

 

1) Adjust the direction of the material strip entering the pelletizer and adjust the length of the water during normal production;

 

2) During production, the broken strip and the strict cover need to be treated by the adjustment process;

 

3) Pay attention to the inspection of the moving knife of the pelletizer, and replace the damaged moving knife in time;

 

4) for the emergence of long bar machi with appropriate vibrating screen, sieve processing.

 

2. even grain

 

Two or more particles side by side are called even particles.

 

The main causes of cattle production are broken when pulling strips, insufficient length of water passing, etc.

 

Main solutions:

 

1) When extruding the pull bar, select the guide bar wheel with appropriate width to separate the material bars connected together;

 

2) Adjust the appropriate length of cooling water, that is, to reduce the grain;

 

3) For the continuous particles, the vibrating screen with appropriate mesh can be used for screening.

 

3. Black spots

 

The presence of black speckled particles on or within the surface of the particles.

 

The main causes of black spots are: cleaning machine is not clean; black spots in raw materials; screw carbonization: environmental pollution.

 

Main solutions:

 

1) In the process of changing production and cleaning, if there is no cleaning, the machine can be cleaned again;

 

2) Strengthen incoming inspection, especially black spots and impurities are more likely to appear in filling mineral powder or flame retardant;

 

3) Pay attention to control and adjust the temperature of the screw barrel and the residence time of the material in the screw barrel to prevent the processing temperature from being too high;

 

4) pay attention to the surrounding environmental health, do a good job in the production of different colors of PFA machine isolation, protection is necessary.

 

4. Discoloration

 

It shows that the color of PFA suddenly changes during the production process, and there is obvious color difference.

 

The main reason for the discoloration is uneven mixing; the cleaning machine is not clean; the temperature is too high; the shear is too strong.

 

Main solutions:

 

1) Strictly follow the mixing process to ensure the uniformity of the mixture;

 

2) After the cleaning of the machine is completed, the annual inspection will be carried out to ensure that the cleaning of the machine F is clean;

 

3) Control the extrusion temperature to prevent the toner from decomposing due to excessive temperature;

 

4) Choose the appropriate screw combination to avoid too strong shear.

This article comes from:www.tflpfa.com