In the process of producing engineering plastic particles, there is a certain probability of encountering irregular particle shape and the presence of impurities, the following will give you a brief talk about the formation of these circumstances and solutions.

strip

The length of more than 2 times the normal grain is long

Causes: the main draw or broken bar, the direction of the material bar is not straight, the material bar is not soaked properly, and the cutting tool of the granulator is worn or there is a gap.

Solution:

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

2) The extrusion process needs to be adjusted when the strip is broken during production;

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

4) Suitable vibrating screen can be used for the long strip.

Binding grain

Two or more grains joined side by side are called connected grains

Causes: The main driving strip is not timely or broken, the length of water immersion is not enough, the head temperature is too high.

Solution:

1) When extruding the brace, use a nylon wheel with a suitable width to separate the material sticks together in time;

2) Adjust the appropriate length of cooling immersion to prevent overheating of the material strip, which can reduce the continuous grain;

3) Properly reduce the head temperature and adjust the temperature of the material strip;

4) For the continuous grain can be screened with a suitable vibrating screen.

Centipede strip

The sections of two or more grains that are not fully cut together are called centipede strips

Causes: the speed of the driving rod is fast and slow, the feeding port of the twin-screw extruder is not enough, the length of immersion is not enough, the cutting tool of the grain cutter is worn, or the gap between the fixed knife and the knife is too large.

Solution:

1) The operator should be uniform when pulling the bar to avoid the occurrence of too thick material;

2) Adjust the appropriate extrusion process to avoid charging at the feeding port;

3) Adjust the appropriate length of cooling immersion to avoid overheating of the material strip;

4) Adjust the gap between the fixed tool and the moving tool, and then replace the new tool.

Dark spot

There are black speckled particles on or inside the particles

Main reasons: the screw is not clean; There are black spots in raw materials; Screw carbonization; Environmental pollution; Artificially brought in.

Solution:

1) In the process of converting the product to pull the screw, if it is not cleaned up, pull the screw again; Cleaning point: "three mouth", screen board and large head behind the filter;

2) Strengthen incoming material inspection, especially in the filled mineral powder or flame retardant more likely to appear black spots, impurities; For example, Z30S or T30S pellets containing wood chips in the package, low grade filled mineral powder or flame retardant; These cannot be used to produce modified plastics with strict black spot requirements

3) Pay attention to control and adjust the temperature of the barrel and the residence time of the material in the barrel to prevent the processing temperature from being too high; That is, according to the formula of each product to design its corresponding extrusion process;

4) Pay attention to the surrounding environmental health and keep the ground wet, do a good job in the production of different color products between the machine isolation, protection is necessary;

5) To regularly clean the auxiliary equipment of the extrusion equipment such as: sink, granulator, etc.;

6) Each time the network is changed, it is necessary to clean up the residual material on the mobile network board and the template to prevent too long carbonization;

7) Pay attention to the floor bar is strictly prohibited from entering the granulator to prevent dust;

8) Prevent the generation of plastic static electricity, static electricity is easy to absorb dust.

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Change color

The performance is that the color of the product suddenly changes in the production process, and there is an obvious color difference

Cause: uneven mixing or incorrect mixing; Cleaning machine is not clean; The temperature is too high; Shear is too strong; The backadmixture has impurities.

Solution:

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

2) After the cleaning machine is completed, special personnel check to ensure that the cleaning machine is clean;

3) Control the extrusion temperature to prevent the decomposition of toner caused by high temperature;

4) Choose the right screw combination to avoid too strong cutting;

5) Make sure that there are no impurities in the back admixture.

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Vacuum bad grain

The section has two or more vacuum eyes or foaming

Causes: insufficient vacuum, vacuum return, vacuum system bad, bad seal and so on.

Solution:

1) Regularly check and maintain vacuum pump and vacuum pressure gauge;

2) Clean the vacuum tank, vacuum chamber and vacuum pipe in time;

3) Properly control the flow of circulating water of the vacuum pump;

4) Solve the vacuum return and ensure that the vacuum cover is sealed well.

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Iron filings or other metal particles

There are iron filings or other metal particles on or between the plastic particles

Causes: screw wear, knife is broken, raw materials have iron filings or other metal particles.

Solution:

1) Check whether the screw, moving tool, vibrating screen, etc., is damaged;

2) Check whether there are corresponding metal particles in the raw materials;

3) For bad products, strong magnetic or other metal separators can be used to screen out metal particles;

4) Add filter for non-enhanced cars.

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Poor plasticization

From the particle section, there is refractory material, or surface black phenomenon

Causes: the heating temperature is too low, the raw material has impurities, the feeding speed is too large, the screw shear is too weak, and the lubricant in the formula is too much.

Solution:

1) Control the temperature according to the process regulations, and appropriately increase the temperature when poor plasticization is found;

2) Check whether there are impurities in the raw materials or insoluble substances mixed in the process;

3) Properly control the feeding speed, so that the plastic in the screw heating and plasticizing time increase;

4) Select the screw combination with moderate shear capacity;

5) Adjust the formula appropriately.

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hypermoisture

Look at the glossy water from the surface of the strip, or feel the grain tide with your hands, or drip water under the grain cutter and other similar phenomena

Causes: the material strip is soaked in too much water, the time strip is not reached when driving, the speed of the grain cutter is too fast, the wind of the wind knife is too small, and the distance between the grain cutter and the wind knife is too close.

Solution:

1) Properly adjust the length of the material strip immersed in water;

2) When drawing, the material strip is divided immediately after entering the granulator;

3) Properly adjust the speed of the grain cutter and the height of the whole material bar support;

4) Ensure that the wind knife wind is large enough, if necessary, use two typhoon knives;

5) Properly adjust the distance between the grain cutter and the wind knife.

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Crushed material strip

After the grain cutting machine, many small pulverized particles are produced

Cause: Plastic static electricity, they adsorbed in the vibrating screen under the feed mouth of the main reasons for the fragmentation are too much water, the cutting tool wear, too much filler material is too hard and so on.

Solution:

1) Adjust the amount of water soaked in the strip;

2) Replace the new cutting tool;

3) Adjust the formula appropriately to reduce the distance between the grain cutter and the wind knife.

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carbonization

At the die head, the leakage coke turns into a black substance, and the plastic surface appears granular coke

Cause: the heating temperature is too high, resulting in scorch of melt; Long-term use of screw without cleaning, coke accumulation; The downtime is too long, and the machine head and screw are not cleaned.

Solution:

1) Often check whether the heating system is normal, if there is a problem with the heating system, solve it in time;

2) Regularly pull the screw or clean the head, clean it thoroughly;

3) The cleaning of the mesh board, filter screen and die head should be timely and clean to prevent carbonization, and the carbonization should be immediately cleaned up the head and screw. Clean, prevent carbonization, carbonization should be immediately cleaned up the head and screw.