What’s the difference between plastic injection molding and 3D printing?


3D printing technology is an additive printing process that creates objects by building up layers of material, while plastic injection moulding uses a mold that is filled with molten material that cools and hardens to produce parts and components.

3D printing and plastic injection molding are each helpful processes in their own right. 3D printing has given engineers the power to create plastic designs at their desks and bring them to life in a matter of hours. Injection molding, on the other hand, is the go-to for quality and value. It is commonly used to quickly and reliably produce high-volume runs of complex plastic designs. 


· Quick turnaround times (1-2 weeks)

· Low volume production runs (100 parts or fewer)

· Designs with frequent changes

· Relatively small plastic parts or components


· Longer turnaround times (5-7 weeks for simple parts)

· High volume production runs (1,000+ parts per run)

· Final part design (no more prototyping)

· Parts of any size or complexity

Alternatives to injection molding, especially innovative and experimental 3D printing, have been grabbing recent headlines. But, the reality is that the majority of today’s plastic parts are manufactured using plastic injection molding. The choice is understandable given how the process helps OEMs control quality, costs, and design complexities such as tight tolerances.


Mould design is one of the most expensive and time-consuming parts of the injection molding process. It is also an opportunity for some injection molders to leverage 3D printing to create tools during prototyping that help reduce development time and lower tooling costs. Stereolithography (SLA) 3D printing, for example, can be a cost-effective alternative to metal tool fabrication, as SLA parts are fully solid and isotropic, and can withstand the pressure of low-volume molding.

What is 3D Printing?

3D printing or additive manufacturing is a process of making three dimensional solid objects from a digital file.

The creation of a 3D printed object is achieved using additive processes. In an additive process an object is created by laying down successive layers of material until the object is created. Each of these layers can be seen as a thinly sliced cross-section of the object.

3D printing is the opposite of subtractive manufacturing which is cutting out / hollowing out a piece of metal or plastic with for instance a milling machine.

3D printing enables you to produce complex shapes using less material than traditional manufacturing methods.

A 3D printer based on the Vat Photopolymerisation method has a container filled with photopolymer resin. The resin is hardened with a UV light source.


Plastic injection moulding is the process of melting plastic pellets (thermosetting/ thermoplastic polymers) that once malleable enough, are injected at pressure into a mould cavity, which fills and solidifies to produce the final product.

Hongmei can offer your both 3D printing and injection moulding form design to mass production.


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