Designing Injection Molded Parts

Injection molding is a cost-effective, efficient and reliable process for producing high quality plastic components. It can produce large volumes of components with high accuracy and precision. This is why it’s a preferred manufacturing technique for many industry sectors. However, despite its popularity and versatility the injection molding process is not without its challenges. The design of injection molded parts requires careful consideration to ensure the final product has good surface finishes, strong tensile strength and is dimensionally correct.

The first step in the injection molding process is to fabricate a mold. This is a metal block of steel or aluminum that will be used to manufacture the final plastic part. The mold is like the negative of the part, it will capture all the geometry and surface texture to be incorporated into the finished injection molded component. The tooling must be made from a material that can withstand the clamping and injection pressures applied by the machine – which can range from 20 tons for a small, high precision injection molded component to thousands of tons for an entire residential garbage can or recycling bin.

Once the mold has been fabricated it must be approved for production by the plastic manufacturer. This is done by reviewing the design for any potential problems and testing the tooling to ensure it can withstand the injection molding process. The design should also be reviewed for any areas where additional support or reinforcement is required, this is often found in areas that will have a high stress load, such as corners and ribs.

Injection molded parts can be manufactured using a wide variety of thermoplastic materials. The most common are polyethylene (PE) and polypropylene (PP). These two materials offer a variety of benefits including excellent mechanical properties, chemical resistance and a customizable shore hardness. These material properties make them well suited for a number of different applications, including:

When designing injection molded parts the wall thickness of a component should be considered carefully. Thicker sections of the part are more prone to warping or sinking than thinner sections. This can impact the appearance of the final component and reduce its tensile strength. It is best to aim for a uniform wall thickness throughout the component.

Another factor to consider when designing an injection molded part is the addition of fasteners. There are three ways to incorporate threads into an injection molded part: by modelling the thread directly onto the component, by modelling a boss where the screw can be attached or by including a threaded insert. Modelling a thread directly onto the part is not recommended, as it creates undercuts that are expensive and time-consuming to manufacture. By designing a boss where the screw can be attached you eliminate these undercuts and reduce your design’s manufacturing costs and lead times.

It’s important to note that when designing injection molded parts the movement of any side-action cores must be taken into account. These elements can add significantly to the complexity and cost of a mould, especially when they need to move around an undercut in the final part. Ideally, these elements should be located away from stiffening features such as corners and ribs, and have an angle of departure greater than 30o. plastic injection molding

Leave a Reply

Your email address will not be published. Required fields are marked *