What causes double alloy screw lock phenomenon

Published on:

2023-03-14

Double alloy screw of injection molding machine is an important part of injection molding machine. Its function is to transport, compact, melt, stir and press plastics. When the screw rotates, the plastic will be in the inner wall of the barrel, the bottom surface of the spiral groove, the advance surface of the spiral rib and the plastic

What causes double alloy screw lock phenomenon

The double alloy screw of the injection molding machine is an important component of the injection molding machine. Its function is to convey, compact, melt, mix and press plastics. When the screw rotates, the plastic will cause friction and mutual movement between the inner wall of the barrel, the bottom surface of the spiral groove, the advancing surface of the spiral ribs, and between plastics. The manufacturer of double alloy screws analyzes the causes and preventive measures of the locking phenomenon of double alloy screws.

There are generally five factors leading to this situation:

1. The screw or barrel is deformed.

2. The barrel temperature is too low or the filter plate is clogged, causing the barrel pressure to rise sharply and causing screw deformation.

3. The design of the screw barrel of the injection molding machine is unreasonable, and it is easy for the screw design compression ratio to be too large, and the screw will deform during use.

4. The thermal expansion coefficients of the materials used for the screw and barrel of the injection molding machine are too different. When heated, the feed seat of the injection molding machine barrel is cooled, but if the screw is not cooled, it may lock.

5. Foreign matter enters the barrel and blocks the screw. If it is a ferrous metal foreign object, it will cause great damage to the screw and barrel.

How to prevent the double alloy screw of the injection molding machine from locking:

1. Cool the screw in the feed section;

2. Increase the temperature of the feed throat;

3. Reduce the temperature of the conveying section;

4. Reduce overflow in the metering section;

5. Increase the gap in the feed throat part.

In most cases, the best way to avoid locking problems is to reduce the rod diameter of the feed section by at least 0.002mm per millimeter. Because most plastics are fed in pellet form, increasing the screw gap at the beginning of the feed section is unlikely to affect the performance of the extruder, but will greatly reduce the possibility of the screw locking in the extruder barrel or throat .

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Dongguan Xingyou Machinery Equipment Co., Ltd

Phone：‭‬86-769-81661345

Address: No. 63, Shuan Road, Humen Town, Dongguan City, Guangdong Province