Design engineers have various options when choosing a plastic injection molding process to best suit their specific application. Each of the three primary methods — hydraulic, electric, and hybrid — feature unique benefits and drawbacks. To make the right selection for your project, it’s important to have a full understanding of how these methods differ and what they can offer you.
Ever since its introduction in the late 19th century, plastic injection molding has revolutionized the way we create plastic products. Although the technology has evolved significantly over the years, many injection molds today still fall into two main categories: hot runner and cold runner systems. Each of these systems has their own benefits and limitations which make them better suited for specific applications.
Understanding the differences between these technologies can help you have a more productive and informed discussion with your plastic injection specialist to determine the most feasible option for your unique application.
When engineering the wall thickness of a plastic part, a careful balance of weight, geometry, and budgetary considerations must be maintained. For example, while thick plastic walls offer more strength, they also have a greater tendency to warp during the cooling stage of the manufacturing process.
As plastic injection molding methods continue to advance and evolve, allowing for enhanced flexibility and more sophisticated customization options, molding companies must be able to stay ahead of the curve in order to offer clients the latest technologies and highest-quality end products.
The success and precision of a part depends on the quality of its mold, but building a reliable, long-lasting tool can take a considerable amount of time — and requires a great deal of accuracy. Also, molds are often one the largest capital investments in a project, so it’s critical that tooling is built right the first time around. This is particularly important in high-volume injection molding projects, where molds can be extremely complex.
With the use of injection molding presses and high-performance resins, plastic injection molders are able to craft a broad range of quality custom parts. Just as all resins are unique, these sophisticated machines offer varied capabilities and performance options depending on press size and type.
While plastic injection molders will help you determine the size of the machine needed to get the best result, a project designer or engineer will get a good estimate based on some basic information. By knowing approximately what size machine will be required, you can better source a plastic injection molder that will meet your needs.
Our website is frequently visited by product designers, engineers and purchasing agents who are looking for information on plastic injection molding. With this in mind, we created a series of "Basics 101" type articles that are developed to give our readers a better understanding of the presses, processes and pitfalls in our industry.
We begin our series with information on the basics of plastic injection molding presses. We hope you find this information useful. If you have specific questions, please do not hesitate to contact us.
Injection Press Basics
While plastic injection molders will help you determine the size of the machine needed to get the best result, a project designer or engineer can get a good estimate based on some basic information. By knowing approximately what size machine will be required, you can better source a plastic injection molder that will meet your needs.
A perfect, precision part begins with the mold. Building the tool takes time and a great deal of accuracy. It can also represent the largest investment in the manufacturing process, so getting it right is critical to the success of a project. If your goal is to manufacture parts with a high degree of precision in large-volume, the tooling becomes even more complex.
When plastic meets the mold
The tool and the molding process are customized based on the type of plastic. Plastics that are amorphous are less free-flowing and tend to shrink less than crystalline or semi-crystalline plastics, which offer better flow, but higher shrinkage. For this reason, many projects call for engineering resins that provide a better melt and less shrinkage. Plastic suppliers provide information on the shrinkage rate of their resins along with temperature and melt flow rate recommendations.