In the previous article, I went over the PROS and advantages of injection molded parts when compared to 3D Printed ones. In this article, let’s go over the CONS and disadvantages. As the saying goes, ‘There is an equal opposing force to everything.”
DISADVANTAGES OF INJECTION MOLDED PARTS
DISADVANTAGE #1 – COST
This may contradict the number one reason in the previous article. In that article, I mentioned that one of the main reasons why injection molding is advantageous is because of its low cost. On the opposite side of that however, injection molded parts can also have some very high upfront costs.
For example, if we were to outsource our aluminum molds and get them machined elsewhere, it would typically cost anywhere between $1,500 to $5,000 for one mold! No, that is not a typo. One mold can really go as high as $5,000 to be made, and sometimes even more, depending on the part’s complexity.
If we do not machine our own aluminum molds in-house, let’s just say that our prices will not be as competitive as it is right now. It will definitely be much higher. The reason why we can offer lower prices for our injection molded parts is because we manufacture them in-house in our shop. Since we get to save a lot on production costs, we get to pass on those saving to our customers.
DISADVANTAGE #2 – DETAILS, DETAILS, DETAILS!
In my experience with both 3D Printing and Injection Molding so far, 3D printed parts can produce far better details than injection molded ones. CNC machines have to “CUT” away materials from a block of aluminum (the term for this is “SUBTRACTIVE MANUFACTURING”), while 3D Printers “prints” or adds layers of the objects from the bottom up in order to print an object (the term for this is “ADDITIVE MANUFACTURING”). Although injection molding machines can pump out parts very quickly, it can also produce parts that lack some details.
Now, I am not a manufacturing expert nor am I a master mold maker, so I can only speak from my own experience. I know there are CNC Machines out there that can cut VERY detailed molds and produce very detailed parts. However, these are very expensive and are commonly used in commercial settings. For a small business like myself, it simply wouldn’t be practical to have in our shop.
DISADVANTAGE #3 – NO ROOM FOR ERRORS
This one is more on the manufacturing side of things as opposed to the actual part itself, but I remember how terrible it went when I first tried cutting my first aluminum mold with our desktop CNC machine. The two halves of the mold did not match up perfectly when I finished cutting both sides of the mold, and when I injected it with plastic, a goo of slimy hot molten polypropylene plastic was oozing out of the sides of the aluminum mold.
Although quite a learning experience, I promised myself to take my time now on and try my hardest not to make a mistake like that ever again. This whole mess ended up costing me a little bit of money and a lot of time wasted.
Injection molding does not have any room for errors. The mold has to be made perfect and it is simply unforgiving. Any misalignment, misconfiguration or a missed step somewhere, you may end up with a messy situation like mine, or you may end up with a part that is not what you expected. I assume there is a reason why most companies would rather get their molds made professionally, or better yet, would rather get their parts pre-made to sell. There’s just so much that goes into making a mold and there is a steep learning curve.
With 3D Printing, if the print didn’t turn out to be the way you expected it, you simply toss the part away, go back to your 3D modeling program, correct the errors and then print again. You can do this as many times as you want and only lose a few cents for the materials and also some time. For injection molding on the other hand, if the aluminum mold didn’t get machined as you expect, it can be very costly!
CONCLUSION
So there you have it, the opposite and dark side of injection molded parts when compared to 3D printed ones. As mentioned in the article, I can only speak from experience. For Mini Arms Depot, we will continue to injection mold our custom 1:12 scale guns and weapons accessories. It makes sense for us and the ADVANTAGES certainly outweighs the DISADVANTAGES. We like making our products affordable and help our customers save even more money. Being a collector and customizer shouldn’t have to cost an arm and a leg. It should be affordable!