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3D Printing or Injection Molding, Which Is Right For You?

About Injection Molding and 3D Printing

Injection molding is a traditional manufacturing process that produces parts and components by injecting material into a mold. The material is usually heated, liquefied plastic, and as the plastic cools and solidifies, it is produced in the shape of a mold and ejected. Injection molding is typically a four-step process. The first step is mold development, injection, cooling, and ejection. You generally need an injection molding machine to combine all these small processes into one.

3D printing works differently. Instead of forming a mold to shape your product, you do it in three-dimensional CAD software and then have the machine print it layer by layer. That’s why it’s also called additive manufacturing, because it adds material from the bottom up. Using this process, you don’t need a mold. However, you do need to make a 3D file that your printer can use to guide how to produce your model.

The rise of cost-effective 3D printing provides a powerful tool for rapid prototyping and an alternative to injection molding for manufacturing plastic parts and products. Injection molding and 3D printing are both common and effective technologies, but sometimes one of these methods is better for your project. Evaluating certain aspects of the project helps determine whether injection molding or 3D printing is a better fit.

Mini plastic injection moulding machine

How big is your production?

Since injection molding requires a custom metal mold, it is most cost effective to manufacture larger quantities where the cost is split throughout the production process. 3D printing is often more cost-effective for small batches of hundreds or less.

What is your production schedule?

3D printing has a very short lead time, but actual production is much slower than injection molding, which is one of the fastest manufacturing methods after the mold is complete.

Does your product have an unusual shape?

Some shapes may be more challenging for injection molding or may require additional tooling, increasing the cost. 3D printing may be better suited to designs with spaces, gaps, branches, or complex structures or other elements that make it difficult for injected resin to fill the mold properly or for parts to pop out of the mold.

What are the requirements for surface treatment of the product?

3D printing may produce a slightly rougher surface or visible layering. In injection molding, there is no need to worry about molding ridges and molding layers because the material is cast in a single layer with an almost uniformly smooth surface treatment. Furthermore, the injection-molded article can be efficiently post-treated. Injection molding is preferred from the standpoint of good surface finish.

Is there any requirement for the strength of the product material?

Because injection-molded parts are produced in a single step, they tend to be stronger than 3D-printed parts, however in 3D printing, the part is made layer by layer, which affects its overall strength. 3D printing creates significant bumps and structural defects in the manufacturing process, which are not strong enough where the layers meet. These are not usually found in plastic injection molding.

Is there any requirement for the loss degree of product materials?

Because injection molding casts as much material as possible into the mold, it uses exactly the material needed for each design. This makes it a very effective way to mass produce objects without worrying about waste. On the other hand, some 3D printing technologies lose some materials when building support structures, even if the material powder can be reused, it can only be reused a few times without changing the material’s performance.

3D printing produces little waste, such as support structures, from which failed prints must be removed in later production, but when it is used to produce single units or small batches, the waste is less important, and for large batches, the waste is great. Therefore, if you customize a large batch, you can consider using injection molding, do not worry about the problem of material waste.

There is a common misconception in the manufacturing world that 3D printing can replace injection molding and be a stand-alone winner in every respect, but both technologies have their own advantages and disadvantages. With decades of experience in the manufacture of plastics, our team, Tianshiwei, can help you solve your low-volume injection molding needs.

Desktop Injection Molding Machine
Desktop Injection Molding Machine