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What causes bubbles in injection molding?

What causes bubbles in injection molding?

Gas bubbles may stem from flow-front issues, such as converging fronts, jetting, or mold/machine problems such as non-vented core pins, poor venting (try vacuum venting), too much decompression, or resin degradation due to overheating or long residence times.

What is the function of plasticizing unit of injection Moulding machine?

The unit used for this purpose is the plasticizing unit. Plasticizing is melting the material so that it is soft and can be deformed easily in the plastic state.

How can we prevent defect injection?


  1. Increase the injection pressure, speed, and material temperature.
  2. Add some more distance between the mold gates and the mold coolants.
  3. Increase nozzle diameter.
  4. Switch to a hot runner or reduce the size of the main channel.

What type of plastic is used in injection moulding?

The two most common types of this plastic are high-density polyethylene (HDPE) and low-density polyethylene (LDPE). The advantages of polyethylene are high levels of ductility, tensile strength, impact resistance, resistance to moisture absorption, and recyclability.

How do you prevent voids in injection molding?

Common ways to prevent voids include:

  1. Raise the injection pressure to force out trapped air pockets.
  2. Choose a grade of material with lower viscosity to limit the risk of air bubbles forming.
  3. Place gates close to the thickest parts of the mold to prevent premature cooling where the material is most vulnerable to voids.

Why is injection Moulding used?

Injection Moulding (or Molding to use the US spelling), along with extrusion ranks as one of the prime processes for producing plastics articles. It is a fast process and is used to produce large numbers of identical items from high precision engineering components to disposable consumer goods.

What does Plasticising mean?

Verb. 1. plasticize – become plastic, as by having a plasticizer added. plasticise. change – undergo a change; become different in essence; losing one’s or its original nature; “She changed completely as she grew older”; “The weather changed last night”

Who is responsible for defect prevention?

One defect prevention coordinator is responsible for propagating the preventive actins proposed in the project as of that date to the entire project team.

Can a Desma injection molding machine be repaired?

Being a well established organization, we bring forth an excellent assortment of Desma Rubber Molding Machines. The offered machinery perfectly gets repaired in case of any fault & comes with maintenance service.

What causes an injection molding machine to fail?

Causes Insufficient injection-molding machine performance (shot capacity, plasticizing capacity, etc.) Gate cross-section surface area is too small. Molded product thickness is too thin. Poor gas venting. Ⅲ. Countermeasures Increase the amount of material feed.

How to prevent injection molding defects and countermeasures?

Increase the mold gas release. Increase gate cross section surface area. Increase the molded product thickness. Add ribs to the molded product design to improve flowability. Choose a low-viscosity high flow material type. Apply surface lubricant. (Add 0.05-0.1% by weight.) Ⅰ. Description

What is a jetting defect in injection moulding?

Jetting is an moulding defect that can occur in the manufacturing process of injection moulding. Jetting is a snake-like stream which occurs when polymer melt is pushed at a high velocity through restrictive areas.