Rapid prototyping: injection vs. 3D printing?

You may have read, here or there, that 3D printing would replace plastic injection in the longer or shorter term. Our opinion isn't quite as clear-cut!

Originally considered to be competing technologies, These techniques are now widely recognized as each having unique advantages and can even be used together to help maximize production efficiency.

This is why we thought it was important to create this comparison between plastic injection moulding and 3D printing?

WHEN TO USE 3D PRINTING OR PLASTIC INJECTION MOULDING

The use of 3D printing in innovative and experimental scenarios is frequently shown in the media, but the reality is that the majority of today's plastic parts are made by injection molding. This choice is understandable given the way the process allows for quality control, cost control and the manufacture of complex assemblies, by injection moulding or bi-material injection with tight tolerances.

3D printing and the Plastic injection molding are both useful and competitive processes, as are cnc machining by shooting or milling.

3D printing has given engineers the ability to create plastic models from their desks and bring them to life in a matter of hours. Injection molding, on the other hand, is synonymous with quality and value. It is commonly used to quickly and reliably produce large volumes of complex plastic designs.

For project leaders, startups or manufacturers who are wondering if plastic injection molding or 3D printing is the right process for their next project, we'll explain when to use each technique and how they can be used collectively to support each other.

plastic injection vs. 3D printing

3D printing

• Fast turnaround times (1 to 2 weeks)
• Small series production (100 pieces or less)
• Designs with frequent changes
• Parts or components made of plastic relatively small

Plastic injection moulding

• Longer turnaround times (5 to 7 weeks for single parts)
• Mass production (more than 500 pieces per series)
• Final design of the part (Minor modifications) Parts of any size or complexity.

What about the performance of the prototypes?

Obviously, 3D printer or resin manufacturers will tell you that 3D printed parts are resistant, and capable of this or that, and that is generally TRUE!

The same applies to the parts injection moulded plastics Plastic.

The most important point is knowing where you come from in order to understand where you're going! (That's philosophical, isn't it?)

Small series

• Your product will be made in 3D printing No problem, your prototype will be the first in a series of XX units. You can carry out representative assembly and usage tests
• Will your product be manufactured by injection or thermoforming? The prototype will have material, performance, and endurance characteristics that differ from your series part. It's possible the prototype part will be less performant than the series part (in which case, you are more or less covered), but the reverse is also possible... and in this case, the series part will take a bit longer to develop, and the costs of modifying the moulds will need to be taken into account!

Medium - Large series

• Will your product be manufactured by injection or thermoforming?
  Do not draw hasty conclusions from a prototype made using SLS, SLA or FDM. Even if the material has the same name, its performance is NEVER identical! The 3D printed part can be used to show a concept, get user feedback... to validate a simple assembly function, but not all at the same time! Only a «correct material» prototype will allow you to successfully pass all the validation stages of your project.