What is the root cause of the white point of the light guide plate?

First, the bubble white spots

(1) The resin material is not sufficiently dried

solution:

1. Check if there is abnormal agglomeration in the resin of the dryer. If it is, then re-feed after cleaning the dryer and consider whether the baking temperature is too high, leading to agglomeration.

2. Adjust the temperature and time of the baking process according to different resin materials

3. Reduce the height of the suction cup of the molding machine cup, and avoid the re-adsorbed moisture of the dried resin material due to staying in the cup for a long time.

(2) Leakage at the cup of the molding machine

solution:

Check if the sealing ring of the molding machine cup inlet is damaged or leaked, if any, repair or replace it.

(3) The process parameters of back pressure and speed are unreasonable

solution:

Appropriately increase back pressure, reduce the speed, and extrude the gas

(4) Decompression distance process parameters are unreasonable

solution:

Properly reduce the decompression distance to avoid excessive air mixing into the molten resin

Second, cold glue white spots

(1) The nozzle and the center of the mouth are inconsistent

solution:

1. The mold platen is not pressed. During the production process, the mold is offset, which causes the nozzle to deviate from the center of the die. Adjust the center of the injection molding machine nozzle, and re-install the mold to press the pressure plate

2. Long-term high-speed high-speed operation, the center degree is offset. Adjust the center of the injection molding machine nozzle to prevent leakage of glue, and avoid the leakage of the cold glue formed after the gel is cooled. The injection of the cold glue into the cavity during the next molding process reduces the poor flowering.

(2) The nozzle/nozzle is damaged

solution:

The nozzle and the nozzle are in contact with each other for a long time, which may cause damage. Replace the nozzle/shot to prevent residual cold glue at the gap.

(3) rough inside surface of the mouth

solution:

The surface of the mold has a rough surface. After the last molding, there is residual powder in the nozzle. When the next molding is performed, the resistance of the rubber is large, which causes the peak pressure to rise. The powder causes the light guide plate to be flowered, and the nozzle is polished with fine sandpaper. Smooth the mouth

(4) thimble adhesive

solution:

1, polishing the thimble, making the thimble difficult to glue

2, increase the cooling time, the resin is fully cooled and does not stick to the thimble

3, change the thimble design, reduce the contact area between the thimble and the resin, not only enough tension, but also easy to release the non-adhesive

(5) The back pressure and speed process parameters are unreasonable

solution:

Appropriately increase the back pressure and increase the rotation speed to make the resin material fully melt and evenly

(6) Decompression distance process parameters are unreasonable

solution:

Appropriately increase the decompression distance to prevent cold glue formed after casting from being injected into the cavity during the next molding, thereby reducing the occurrence of poor flowering

(7) nozzle cooling temperature / low temperature of the first nozzle

solution:

The temperature at the nozzle end of the injection molding machine is low (the nozzle is in contact with the mold for a long time, the heat on the nozzle is dispersed on the mold, resulting in a low melting temperature of the resin material at the nozzle end), resulting in the formation of cold material at the nozzle end. Appropriately increase the nozzle cooling temperature / the first temperature of the nozzle

Third, carbonized white spots

(1) Leakage at the cup of the molding machine

Leakage causes oxygen to mix into the barrel, causing oxidation of the resin at high temperatures, resin carbonization

solution:

1. Check if the sealing ring of the material feeding cup of the molding machine is damaged or leaked, if any, repair or replace it.

2. Gluing the barrel and discharging the carbonized resin

(2) The back pressure and speed process parameters are unreasonable

solution:

Properly reduce back pressure and rotation speed, reduce shear heat generated by shearing, and avoid high temperature lead to resin carbonization

(3) The process parameters of the barrel temperature are unreasonable

solution:

Properly reduce the temperature of the material and avoid the carbonization of the resin caused by high temperature

(4) Screw carbonization (carbonized resin sticks to the screw)

solution:

Remove the barrel and screw set for cleaning (polished with copper brush)

Fourth, metal white spots

(1) Dry metal foreign body

Metallic foreign body is mainly metal aluminum

solution:

Cleaning and drying machine (usually new dryer, need to run-in)

(2) Conveying pipes, molding machines, mold metal foreign bodies

Metal foreign bodies are mainly metal iron/steel

solution:

Clean pipes, molding machines, molds (usually new machine/mold, run-fit)

Five, impurities, white spots

(1) Resin material impurities

(2) Packaging paper scraps, thread ends