Manufacturing Processes: Injection Molding and 3D Printing

Manufacturing Processes: Exploring the Fundamentals of Injection Molding and 3D Printing

When it comes to manufacturing plastic parts, product designers have more options than ever before. Injection molding and 3D printing are two of the most popular methods, and they offer unique benefits that can help you achieve your desired fit, form, and function. But which process should you choose? And how can you optimize your design process to bring your products to market on time and on budget? In this article, we’ll explore the fundamentals of injection molding and 3D printing and offer guidance on how to select the right process for your project.

Injection Molding and 3D Printing: Leveraging the Benefits of Both Processes

Gone are the days when product designers had to choose between injection molding and 3D printing. Today, these processes are more advanced than ever, and engineers can leverage the benefits of both to produce higher-quality parts. The question is no longer which process to choose, but rather how and when to use them together.

Engineers are creating roadmaps to bring their products to market on time and on budget, but many of these roadmaps are based on using a single process. As a result, they may not be fully optimized for success. That’s why it’s important to understand the fundamentals of both injection molding and 3D printing and consider how they can be used together.

Injection Molding and 3D Printing: Revisiting the Basics

No matter how many new processes and technologies are introduced, there’s always room for recalling fundamentals. In fact, revisiting the basics can help you make more informed decisions when choosing between injection molding and additive manufacturing.

One of the most important questions you can ask yourself is how the part will be used. Understanding this can help you mitigate risk, whether you choose injection molding or 3D printing. Another key factor to consider is whether the part is a concept or final production. The demands for each can vary significantly, and your approach to manufacturing should reflect this.

Additionally, it’s essential to consider whether the part is simple or complex. Regardless of which end of this continuum defines your part, there are many manufacturability compromises that could derail your intended design. One way to help mitigate risk is to build a list of non-negotiables that the manufacturer must follow to help achieve your design intent.

Understanding 3D Printing Technologies

When designing plastic parts, it’s important to think of 3D printing and injection molding as manufacturing processes that are on the same team with different roles. They each provide unique value but can also complement each other to produce your product. Here’s an overview of the 3D printing technologies you should consider:

Stereolithography (SLA): Available since 1989, SLA uses an ultraviolet laser to cure parts one layer at a time in photo-reactive epoxy resin. It is one of the most accurate 3D printing technologies and is ideal for fine, detailed, small-featured parts as fine as .002” layer thickness. SLA is also capable of producing large parts.

Fused Deposition Modeling (FDM): FDM extrudes thermoplastics layer by layer, with a variety of thicknesses as fine as .005” per layer. FDM uses real engineering-grade thermoplastics and creates functional parts that can withstand rigorous testing. It also offers excellent tensile strength, flexibility, high melting points, chemical resistance, and UV resistance.

Selective Laser Sintering (SLS): SLS uses engineering and high-performance, powder-based materials activated by the thermal energy of a laser in the Z axis to build one layer at a time. SLS uses real thermoplastic base materials. This approach also suggests that you involve yourself earlier in the design process with a manufacturer who will understand your strategy and align processes to fit, providing expertise in material selection, tooling considerations, design-for-manufacturing, and specific technology experience.

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