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What are the reasons and solutions for the low extrusion volume of high-speed injection molding machines?

Update:18-02-2021
Summary:

Customers often report that the extrusion volume gradua […]

Customers often report that the extrusion volume gradually decreases after the PET Bottle Blow Molding Machines is turned on for a period of time, which is mainly caused by the following reasons:

The first reason is that the cold air has been on for a long time, causing the mold surface to be too cold.

At this time, we have to check whether the rubber at the exit of the die surface has been plasticized and melted.

The second reason is that the boot temperature is too low.

At this time, it is necessary to check whether the temperature of each part of the extrusion barrel and the die meets the standard requirements? Although the outside temperature of each part meets the standard, if the heating time is not sufficient, the inside and outside temperatures will be inconsistent; check if there is any heater or thermocouple damaged? If any electrical device is damaged, repair or replace it immediately.

The third reason is that the temperature of the extrusion barrel or die is too high, the screw and barrel of the melting section are worn, the screw is carbonized, and the material is not smooth.

Check the sensitivity of the temperature controller and deal with it appropriately. The die head temperature controller should be of higher sensitivity.

The fourth reason is that the transmission belt is loose or falling off.

The old transmission belt should be replaced immediately, and an idler pulley should be installed if it can be used to adjust the belt tension to prevent the belt from loosening and falling off again.

The fifth reason is the glue sticking in the screw feed part.

Before each shutdown, lower the temperature slightly; wait until the screw feed part is completely out of rubber, and then shut down; when the screw is found to be stuck by the rubber after the start, the screw must be cleaned first. If it is not convenient to clean, Use a plastic rod or a wooden rod to squeeze the material under the feed port forcefully to make the glue sticking to the feed part of the screw move forward. At this time, pay attention to the plastic rod or wooden rod being bitten by the screw, or wood chips falling off , Never use metal rods.


The sixth reason is that the throat of the feeding cylinder has agglomerates.

The water temperature of the cooling water jacket at the throat of the feeding cylinder should be controlled below 40C°. If the filter is clogged, replace it with a new one in time.

The seventh reason is that the back pressure is too low.

The phenomenon caused by too low back pressure is unstable discharge, which can be corrected by increasing the back pressure.

The eighth reason is that the DC motor voltage fluctuates too much. A voltage stabilizer should be installed to ensure the stability of the voltage.

The ninth reason is that the rotation speed of the clamping roller is uneven, or the pressure between the rollers is too large.

At this time, check whether the clamp stick is eccentric? Is the transmission belt worn or loose? When the pressure between the rollers is too low, slippery will occur. Adjust the air pressure or spring to increase the pressure.

The tenth reason is that too much recycled material is mixed into crushing.

It is necessary to reduce the proportion of mixed powder and try not to add recycled materials; if you need to add crushed materials, it is best to make pellets first to stabilize the discharge.

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