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Injection molding vs. 3D printing: all you need to know

Today, companies can use injection molding or 3D printing to produce near-identical runs of complex, high-quality final products. However, you might be better off using one over the other, depending on your project’s specific requirements. If you aren’t sure whether injection molding or 3D printing is better for your project, read on! This article will take a closer look at each process and the advantages and disadvantages of 3D printing compared to injection molding so you can make an informed decision.

All about injection molding

During the injection molding process, molten plastic material is injected into a CNC machined mold of steel, aluminum, or copper that’s the inverse of your final product. After the plastic cools and solidifies, your engineer will eject your part from the mold and move on to post-processing. Injection molding has a wide range of applications, and most plastic products you see on a daily basis are created using this manufacturing process. Common applications include bottle caps, combs, toys, and even car parts.

 

Due to the high cost of tooling, injection molding isn’t ideal for prototyping or small production runs. Instead, use it when you need large volumes of precise and consistent parts, solid parts, or parts with smooth finishes.

Advantages and disadvantages of injection molding

One of the biggest advantages of injection molding is how quick and cost-effective it is at large volumes. Producing the injection mold requires a significant initial investment, but the actual process of injection molding a part is highly automated and can be completed in minutes. You’ll be able to produce hundreds or thousands of parts a day, which in turn helps you rapidly meet demand and quickly lowers your cost per part. Plus, many plastics don’t require any finishing and you can use multi-cavity molds to further accelerate your production timeline. The finished parts will have smooth surfaces, be relatively strong, and lack air bubbles or fissures.

 

However, injection molding has a high barrier to entry. Tooling is expensive, and you’ll need to have a mold made for every part you create. If your final mold has a problem or you want to make a change to the part design, you’ll have to start from scratch and buy an entirely new mold. Those costs can quickly add up. It’s also important to note that it can often take 5 to 7 weeks to create tooling, so injection molding isn’t ideal for prototyping or products with frequent design changes, as these restrictions can impact your designs.

All about 3D printing

3D printing, or additive manufacturing, adds material layer by layer to form complete parts. Fused Deposition Modeling (FDM) is a popular method of 3D printing, but you can also use Carbon Digital Light Synthesis (DLS), stereolithography (SLA), a powder bed fusion process like Multi Jet Fusion (MJF), or others.

 

FDM printing white object

 

Since 3D printing doesn’t require expensive tooling, it’s great for prototyping and low-volume production runs. The lack of molding also makes 3D printing an ideal manufacturing method if you plan on frequently making design changes or offering customized products. If you need to pivot, you can simply alter your design and send it to the machine for printing. 3D printing’s applications expand each day, and you can now find prosthetic limbs, footwear, car parts, and more produced by additive manufacturing.

Advantages and disadvantages of 3D printing

There are several advantages of 3D printing, including low entry costs, less material waste, and a shorter pre-production cycle. Since you don’t need to spend weeks manufacturing a mold, you’ll be able to create prototypes and make design changes quickly. You can have a new part printed within days (or even hours). Plus, since you can print objects on demand, you can create customizable products without incurring significant additional costs.

 

There are, however, some disadvantages to keep in mind. Most notably, 3D printing production runs typically take more time than injection molding (after tooling is complete). You’ll also be limited by your machine’s printing area. Different 3D printing technologies have different maximum sizes determined by the machine. Also, note that some 3D printed parts have a rough surface finish, even with small layer heights. To achieve a smooth surface, you may need to post-process your products, which can lengthen the production process.

3D printing vs. injection molding

When deciding between additive manufacturing and injection molding, neither is fundamentally better than the other.

 

  • If your product is needed in small quantities or has a short lifecycle, consider using 3D printing to avoid investing a significant amount of time and money into tooling.
  • If you’re planning a large production run, injection molding will probably offer you a lower cost per part.
  • If you need to produce a custom part, use 3D printing to cut costs and save time.
  • If you have a complex design, 3D printing might be a better option.
  • If you anticipate changing your design frequently, choose 3D printing.

 

Injection molding and 3D printing aren’t always at odds. In fact, you can use them in tandem to shorten production cycles and cut costs. For example, you can 3D print prototypes for injection molding tooling or use a 3D printed mold if you’re ready to start manufacturing products but haven’t finished creating your final tooling.

Bringing your ideas to life with Fast Radius

Injection molding and 3D printing can both help you achieve your project goals in different ways. It all depends on your budget, design requirements, and desired production time. If you aren’t sure which manufacturing process to use for your project, speak to an expert.

 

When you work with Fast Radius, our team can help you decide which technology is best suited for your project. We can also help optimize your design, pick materials, and more. Contact us today to get started.

 

Visit our resource center to learn about how to get injection molded parts ready for production, designing for additive manufacturing, and more.

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