Plastic Injection Molding

What is plastic injection molding?

Thermoplastic injection molding is a method for manufacturing high-volume parts with plastic materials. Due to its reliability and flexibility in design options, injection molding is used in many industries, including: packaging, consumer & electronics, automotive, medical, and many more.

What are the most common types of injection molding processes?

The traditional thermoplastic injection molding process can be modified to include processes that help to enhance part quality and part design flexibility. Below are some examples:

  • Thermoset injection molding

    Molding with thermoset materials requires heat or chemical means to cross-link polymer chains.

  • Overmolding

    Overmolding is an injection molding process where one material is molded on top of another.

  • Gas-assisted injection molding

    Inert gas is introduced, at high pressure, into the polymer melt at the end of the injection phase of molding.

  • Co-injection & Bi-injection molding

    Injection of two different materials using either the same or different injection locations.

  • Microcellular injection molding

    Use of physical blowing agent, chemical blowing agent (CBA), or mold core-back process to trigger foaming of polymer inside the mold.

  • Powder injection molding (PIM)

    Forming technique for producing small components using powders, typically ceramics (CIM) or metals (MIM), and binding agents

What are some advantages of injection molding?

Injection molding manufactures high quantities of parts, faster than other manufacturing methods (machining or 3D-printing). High accuracy and automated processes encourage identical part creation, promoting low labor costs. Customization allows flexibility in part design (ex. molded-in inserts) and material properties (ex. color, clarity, strength, & flexibility).

What challenges can appear with injection molding?

Part designers, mold engineers, and other manufacturing stakeholders can all run into their own challenges, which ultimately affect part quality, and they often need to work together to resolve if not caught in the early design stages.

Some examples of these challenges include material variations, weld lines, sink marks, warpage, long cycle times, and incomplete cavity filling.

How does injection molding simulation software help?

Molding simulation can help designers and engineers to understand risks early in the design process, allowing the ability to address these before becoming fully invested. Simulation software gives engineers, mold makers, and other molding professionals accurate digital prototyping solutions, and help bring better products to market faster.

Moldflow simulation can be paired with other simulation tools, including mechanical stress, vibration, motion, computational fluid dynamics (CFD), and Multiphysics, providing a fast, accurate, and innovative approach to solving the most challenging design problems.

How can Moldflow injection molding simulation software help?

  • Image of a plastic part simulation temperature variations

    Predict surface finish defects

    Analyze fill patterns and effects of geometry & process setting changes, such as sink marks.

  • Image showing Moldflow simulation of a warped box part

    Predict & prevent warpage

    Investigate the causes of warpage, then examine options to minimize or correct part deflection.

  • Image of Moldflow’s material database

    Optimize designs for lightweighting

    Analyze and compare advanced materials for lightweighting efforts, such as with automotive components.

  • Image of simulation Moldflow comparing traditional and conformal cooling

    Reduce part cycle time

    Predict part cooling efficiency. Experiment with advanced conformal cooling or induction heating before investing in costly molds.

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Student and educators may be eligible to receive a free subscription to injection molding simulation software, Moldflow Adviser Ultimate.

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