INTRODUCTION Injection molding is a versatile method of manufacturing that provides a repeatable, high-quality

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  • INTRODUCTION Injection molding is a versatile method of manufacturing that provides a repeatable, high-quality and consistent way to produce parts. Although some components of injection molding have evolved with new advances in science and technology, the overall process remains the same. Molten material, commonly of plastic, ceramic, or metal, is first forced into a mold. After hardening into the desired shape, ejector pins remove the material from the mold. Once the initial molding process is complete, there are multiple ways to modify the product further, although this is not required.

    Improving the injection molding process has advantaged its efficiency and set this technique apart from other manufacturing processes. The following eight chapters describe the different advantages of the injection molding process when making parts. These benefits include complete control of the parts' physical form, reduced time and resource consumption, higher structural integrity, and the ability to prototype parts before a production run. Many of the advantages listed here are made possible by the use of scientific injection molding (SIM), a new development in the injection molding field. Before the introduction of SIM, injection molding was considered more a mechanical and physical process than an analytical and logical one. SIM allows part making to become a data-driven, scientifically rigorous procedure, focused on repeatability, efficiency, and consistency.

  • DETAILED FEATURES Whether working with plastic, metal, or ceramic, injection molding can detail materials when crafting parts. Because the liquid material can flow into every part of a mold, this process ensures that no features are missed. While it solidifies, the liquid is held at high pressure inside the cavity. The ability to detail the final part depends on the material type and its viscosity in a molten state. Materials with high viscosity do not flow as smoothly as their less viscous counterparts and are therefore less suitable for fine detailing.

    Molding features this way not only create precise details but ensures that parts fit together correctly and perform their specific functions, such as anchoring a larger assembly or interacting with another machine. While intricate detailing might not directly influence the overall body of a part, incorrect molding could contribute to multiple problems, such as increased wear and even dysfunction. Therefore, detailing features is critical step to ensure the resulting products moves and functions properly.

    The detailing capabilities of injection molding are arguably more precise and efficient than other manufacturing methods. The simple physics of fluid flow in an automated environment creates an accuracy and precision which might be impossible to achieve if manufactured manually. For example, features can be molded on the scale of a few millimeters or less through injection molding.

  • INTRICATE SHAPES Injection molding can create intricate part structures in the same fashion it finely details, by using fluid flow. Because many structures are composed of both individual intricacies and larger, substantial features, most manufacturing processes will create complex structures piece by piece which leads to increased assembly cost and design time. Injection molding allows a complex structure to be made holistically, eliminating the need for additional design or assembly time and significantly reduces the likelihood of errors that could affect the final part.

    Manufacturing separate, intricate shapes is not as cost-effective as injection molding. The time needed to design, assemble, and test multiple pieces can cost a significant amount of money. Molding collective pieces as a single whole can eliminate such inefficiency. While injection molding is a material specific process, it ultimately saves time, labor, and money.

  • PRODUCTION EFFICIENCY Production efficiency in the injection molding process is immensely high for multiple reasons. Molds can be used for long periods of time before becoming vulnerable to significant wear or deformation, and by merely reworking the mold, alterations can be made to the structure of parts.

    Very little waste is generated during the injection molding process. Since the material is molten when injected it is possible to reuse scrap. As long as the material has not been modified or significantly changed from its initial molded state, it has the potential to be recycled. Defective parts can also be melted and used as new molding material. Almost any possible error in the molding process can be rerouted to form new parts and prevent waste.

    Compared to other manufacturing methods injection molding is one of the fastest. It is limited only by the amount of time it takes for a part to solidify in the mold. Since parts can be made quickly production as a whole is cheaper than many other manufacturing methods. The cycle times of injection molded parts are significantly lower than other manufacturing methods. Innovations such as multiple cavitation tooling, which molds numerous pieces at once, can also increase manufacturing efficiency. This tooling increases the production speed of both individual part and batch manufacturing.

  • RESINS & DURABILITY A wide variety of resins and plastics are suitable for injection molding. There are more than 15,000 resins currently available, and the number of materials designed for injection molding is currently increasing at a rate of approximately 500 per year. Many of these materials are chemically engineered to serve specific purposes. For example, some resins are best suited for medical devices while others are better suited for industrial machinery.

    Resins and plastics can be combined in a process called co-injection molding. This process creates a molded part in two separate steps, and is also sometimes known as two-shot molding. Substrate pieces are constructed during the first injection process. Once the substrate has been molded a second injection covers the substrate with another resin. This allows for the creation of a wide range of applications such as soft-touch, multi colored components, molded assemblies and more. The combination of materials gives the part unique properties. The infinite number of different resins and plastics makes their combinations, and further applications, near limitless.

  • AUTOMATION As automation becomes more prevalent throughout the injection molding industry it continues to push the manufacturing method forward as a high quality and cost effective way to produce products and components. Not only does automation reduce the cost of labor associated with the production of goods, but it also removes a lot of human error from the process.

    Automation allows injection molding machines to run in a way that reduces manufacturing variability. This means that your parts will be produced in a very consistent and robust manner ensuring quality run after run. Combining automation with Scientific Injection Molding processes allows machines to be taught to automatically divert suspect parts from being packaged and lens itself to more effective quality practices.

    By replacing non-value add labor with automation manufacturers are also able to focus on improving the skill, and making better use, of their labor. This means the labor being performed on the manufacturing floor is adding value to your products rather than being a unnecessary cost. It also opens up time to allow for training and development of the workforce.

  • PROTOTYPING Prototyping is the process in which developing a small-scale run of parts prefaces large-scale production. Small runs critique before creating, and "pre-check" parts' mold and function, while testing the limits of the design of experiments (DOE) process that determined the initial part design. The prototyping process also can serve as a form of quality assurance, ensuring that the parts measurements and details are accurate.

    The process to develop prototypes is very similar to creating the actual part, using the same materials and injection process. Sometimes it is cheaper to construct prototypes with different materials. For example, one might create a prototype for steel parts from aluminum or heat-resistant plastic. Prototype materials can be reused to create other prototypes if necessary. Using prototypes constructed from materials different than the final parts, however, can limit accuracy when measuring the reactivity and stressors put on a part during testing.

    While prototyping is not a required step in the injection molding process, the advantage it confers in making sure that parts function properly can be invaluable. Incorrectly made parts with defects that could have been caught in testing force the company to waste money, recalling or replacing them. A bad parts run could also negatively impact the company's reputation.

  • EFFICIENCY & CONSISTENCY Before injection molding became commonplace, it was not easy to measure the consistency and efficiency of the manufacturing process. Overproduction was a common strategy, assuming that any spare parts produced would cover the deficit of defective parts or errors. Though well-intentioned to counter human error and production mishaps overproduction caused more problems than it solved. Often wasting resources and money in best and worst case scenarios. In the early years of molding this was considered necessary because no better strategy or technologies existed.

    Scientific Injection Molding (SIM) has mostly eliminated the need for this overproduction s