Common Reasons Why the Screw for Injection Molding Machine Does Not Feed

Injection molding machine operators may encounter various challenges related to the feeding of the screw. Identifying and addressing these issues is crucial for ensuring a smooth and efficient molding process. Here are some common reasons:

Material Issues:

Too Much Added Material in Plastic: The inclusion of excessive additives, such as fillers or reinforcing agents, can disrupt the flow characteristics of the plastic material, leading to feeding difficulties. This may result in poor dispersion and uneven melting within the barrel.

Inaccurate Temperature Control: Temperature plays a critical role in the injection molding process. If the temperature at the rear end of the barrel is too high, it can affect material flow. Operators should adjust temperature settings and inspect the cooling water circuit for potential blockages.

Glue-Plastic Wrap on Screw: In some cases, the screw can become covered with glue or plastic, causing it to rotate along with the plastic material. This issue can impede proper feeding and requires cleaning and maintenance.

Worn Screw and Barrel: Wear and tear on the screw and barrel, or abrasion of the rubber ring, can lead to leakage of plastic material and hinder its transportation to the front end of the barrel. Regular inspection and timely replacement of worn components are essential.

Excessive Oil in Plastic: Adding too much oil to the plastic material can cause the screw to slip, reducing its effectiveness in feeding. Maintaining the correct oil-to-plastic ratio is crucial for optimal performance.

If the plastic resin being used has high moisture content, it can lead to poor feeding, too. Drying the material before processing may be necessary.

Improper Screw and Barrel Design: If a newly replaced screw is not feeding properly, it may indicate design issues. The screw groove in the feeding section may be too shallow, impeding plastic movement. Similarly, the barrel's feed opening design should be checked for compatibility.

Large Plastic Pellets: The use of excessively large plastic pellets can lead to bridging, causing damage to the screw. Properly sized pellets should be used to avoid this issue.

Blocked Feeding Port: A blocked feeding port in the barrel can result in feeding problems. Operators should check for molten plastic sticking to the port and clear any obstructions to facilitate smooth material flow.

Machine Calibration:

Incorrect Machine Calibration: If the injection molding machine is not calibrated correctly, it may not provide the necessary force or movement to the screw for effective feeding.

Hopper Issues:

Hopper Design or Contamination: Problems with the hopper, such as poor design or contamination, can impede the smooth flow of material into the screw.

Back Pressure:

Inadequate Back Pressure: Back pressure is used to build up pressure in the barrel and promote proper mixing. If the back pressure is too low, it can result in poor feeding.

Check Valve Issues:

Malfunctioning Check Valve: The check valve ensures that molten plastic only flows in one direction. If the check valve is not functioning properly, it can cause feeding problems.

Make sure you choose the injection molding machien screw properly direct from manufacturer or original.