This is a topic one could easily write an entire book on.
There are many things that injection molding can do that FDM printing cannot or cannot do as well. Just the range of materials available for injection molding dwarfs what is available for 3D printing of any type. In many applications the specific polymer grade you use is very important to the function of the product. The process also results in parts with isotropic properties where the orientation of the layers on a FDM part significantly affects the part properties.
Design wise you can achieve much higher detail and finer functional features in injection molding. You can’t really put a specific texture on FDM parts like you can on an injection molding tool, nor can you do fine features like snaps or live hinges nearly as well. On the other hand, since an injection mold has to open to release the part, you have a lot more flexibility in the design of a 3D Printed part to add features that would be impossible to injection mold (internal cavities, undercuts without pass cores or a way for a slider to release, etc.).
In terms of manufacturing there are a few considerations that might make injection molding or FDM more suitable. Injection molding shines when you needs thousands of the exact same part at low cost. FDM might be a choice if you need a handful of a part, or to print parts that are different each time (say a part that is sized to a particular person).
This is a topic one could easily write an entire book on.
There are many things that injection molding can do that FDM printing cannot or cannot do as well. Just the range of materials available for injection molding dwarfs what is available for 3D printing of any type. In many applications the specific polymer grade you use is very important to the function of the product. The process also results in parts with isotropic properties where the orientation of the layers on a FDM part significantly affects the part properties.
Design wise you can achieve much higher detail and finer functional features in injection molding. You can’t really put a specific texture on FDM parts like you can on an injection molding tool, nor can you do fine features like snaps or live hinges nearly as well. On the other hand, since an injection mold has to open to release the part, you have a lot more flexibility in the design of a 3D Printed part to add features that would be impossible to injection mold (internal cavities, undercuts without pass cores or a way for a slider to release, etc.).
In terms of manufacturing there are a few considerations that might make injection molding or FDM more suitable. Injection molding shines when you needs thousands of the exact same part at low cost. FDM might be a choice if you need a handful of a part, or to print parts that are different each time (say a part that is sized to a particular person).