One disadvantage of FDM parts are that they are usually weaker than injection molded ones because of how the extruded lines have to fuse together rather than just being moulded in one piece.
Sure its good for “rapid” prototyping but the cost and time advantage dont scale. If I need exactly 1 of something FDM will almost always cost less and take less time. If I need 100-1000-10,000 of something FDM will cost far more upfront for printers than the cost of molds and doing a large injection run.
So it really comes down to what you need and want. For testing, and developing something FDM is fantastic, but once you need to scale, traditional manufacturing will win every single time by a mile!
Wow, there are some really in depth and great replies thank you everyone.
Right now for my use cases some of the advantages I see are:
- Rapid Prototyping
- Using FDM where injection molding would struggle, examples include articulating toys.
- Low volume production runs
Does anyone have a multi-filament printer? I am not quite sure how this would compare with injection molding, but I am able to get relatively fine color changes on a single part. See picture of an earring that I am prototyping.
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).
3D prints are great for those one off things. In the past I’ve printed replacement parts for a swimming pool, a g-clamp I needed for a one off task, I’ve fixed a rotary clothes line…
My most recent print was an AirTag holder for my wallet. Aviator who make the wallet wanted €35 for their one. Mine cost me probably 5p in plastic 😂
Yea, the versatility of 3D printing is a perk. You don’t need to buy a mold just download/create what you need and viola a few hours later its there.
Advantage of 3D printing is that you can virtually print anything you want and have it available to use within minutes to a few hours without leaving your place or order something to be delivered. The down sides are that it usually needs to be designed with 3D printing in mind. It’s also a bit weaker due to the layer adhesion, it’s surface finish is not as precise (resin is another story though) Also with a decentralized manufacture there is no QC possible so if you design something and put it up online the quality will vary depending on who prints it and on what. Finally, there’s a problem with IP, when you manufacture a mold and inject then sell, you can charge per item, with 3 D print you may pay for the STL but the. There are no restrictions on how many copies you can make. So it’s a challenge to adapt pricing of designs if you’re looking to make a profit from it.
Weaker, not smooth without postprocessing, not food friendly, and of course much slower.
