Why is material selection important for injection molding?
Contents
1. Available injection molding materials and their characteristics
2. Material selection of injection molding
Injection molding under vision: Step 1, design your part. In step 2, prototype and iterate to optimize your design. The third step is to enter the production stage. Wouldn't it be great if product development was so easy? By now, you may already know that this is not the case. There are still several steps and considerations for the plastic injection molding process to consider, which may be why you are here. Among them, the material selection of injection molding is the primary consideration. Although the process of material selection of injection molding is certainly worth taking a separate step, in many respects it is affected by, and may have an impact on, most other steps, and it will definitely affect other steps. The last step of development: production. The details of how you perform the resin selection process for injection molding are best defined by the way you and your development team work. But in general, the sooner you start thinking about it, the better. Of course, an in-depth understanding of the available injection molding materials and their characteristics is never a bad thing.
Available injection molding materials and their characteristics
Resins for injection molding have many qualities that affect their behavior, performance, and ideal application, both in the production process and in their final use form. Since we will introduce the possible role of each of these qualities in the requirements and aspects of product design and function, let us quickly review their meanings. The hardness meter is called the hardness of the resin used for injection molding. When referring to the hardness of a durometer or injection molding material, you are referring to its ability to resist wear or indentation when subjected to external forces. For aesthetic reasons, a hardness tester can be considered. For example, in the case where the material should not be worn or scratched. However, it also measures at the molecular level, which may be a factor in higher precision applications. Flexibility, flexibility is the ability of resins for injection molding to restore its original shape after bending, without breaking or breaking. Remember, according to the durometer, hard materials can also be very flexible, while soft materials may be more brittle and therefore more prone to breakage. The quality of the first two injection molding materials is not interchangeable. Temperature resistance, which refers to the behavior of a material under extreme temperature conditions (hot or cold). Certain materials may start to weaken or even melt at higher temperatures (or, for thermoset materials, burn), or they may become more brittle when extremely cold. UV resistance. For outdoor applications, UV resistance is as important as temperature resistance. UV resistance measures the ability of a material to maintain its characteristics (strength, shape, appearance) when exposed to direct sunlight. The above factors affect all the reference material properties of the resin in its final form. Nevertheless, different materials also have different characteristics in the production process, which can play a role in the material selection of injection molding. These include: melt temperature, the temperature required to transform solid resin particles into molten liquid for injection. Viscosity, this property is related to the way the material flows through the mold-the more viscous the material, the thicker the liquid form. Melting curve, different types of resins for injection molding melt in different ways. Molecularly speaking, resins are divided into two categories: amorphous and semi-crystalline. The important conclusion drawn from this distinction is that as the temperature rises above a certain melting point, amorphous resins will gradually melt, while semi-crystalline resins will melt completely after reaching a certain melting point. This difference can play an important role in production, and we will see this soon. Although the above list provides an understanding of the types of material properties that resins for injection molding may have, let's look at some of the questions they can provide answers to.
Material selection of injection molding
Material selection of injection molding is a key consideration for all these and more. For example, for consumer parts, if aesthetics are important, materials that are easy to dye, paint, or surface finishing may be more needed. For aerospace components, heat resistance may be a priority. How complicated will the production be? Similarly, production complexity may involve multiple factors: is your part itself complicated, and is the mold complicated? Will your part be overmolded? Will more than one material be used? When considering these issues, please look for the corresponding choice in accordance with the available injection molding materials and their characteristics as described above: For complex parts, lower viscosity may be preferred, so that the material can more easily flow through the mold and fill the entire mold. Cavity. For more complex parts, a lower melt temperature may also be useful to ensure that resins for injection molding stays liquid for a longer time as it flows into the mold cavity. If multiple materials are mixed in production, melt distribution is a key issue and should be considered together with the production and end-use characteristics of the material. If amorphous and semi-crystalline resins are mixed, they will not melt uniformly, so it is unlikely to fill the mold correctly. For overmolded parts, please ensure that your injection molding resin does not cause any adverse chemical reactions to the surrounding resin molding materials.
More considerations
What is the intended use of the part? Will your parts be used in high-impact applications? Be sure to consider both the hardness and flexibility of the resin used for injection molding to confirm the appropriate strength without the risk of breakage or breakage. Harsh environments, such as use in aerospace, underwater and even aerospace industries, also have a significant impact on materials, such as temperature adaptability, UV resistance, chemical interaction and resistance, and so on. Of course, more traditional uses such as children's toys may also be considered bad environments. Therefore, the materials selected for these applications should be more resistant to breakage and damage. If you are ready for the material selection of injection molding for your project, or just want to learn more about the available injection molding materials and their characteristics in the early stages of product development, please contact Pubo immediately.
Tags: Material selection of injection molding, available injection molding materials and their characteristics, resins for injection molding
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