3D Printing has long been discussed as a potential alternative to injection molding. And there are many advantages to the technology that make that the case from a design perspective.
But injection molding is generally considered to be a less expensive option at scale. That is because when hundreds of thousands of parts are being produced the cost of the parts is so low and the cost of the mold is easily amortized across all of those parts. So if you can take the upfront cost, injection molding can be cheaper than 3D Printing.
But that is only at the manufacturing stage. There are so many other factors in the supply chain that contribute to the cost of a product. And really 3D Printing is arguably less expansive than injection molding when you take all of those other factors into account. There is the upstream design and iteration that is quicker and cheaper. And there is the downstream assembly and warehousing that can be substantially reduced.
Injection molding is only ideal if you are making millions of parts and can afford to build and maintain that inventory. In all other instances 3D Printing should be an option when choosing manufacturing methods.
So let's go through all the reasons 3D Printing is a cheaper alternative than injection molding.
Quicker Design Turn Around
As soon as you have created a product you are competing. Speed can make the difference between a successful launch or having to wait a full year until the next Christmas Season.
With traditional manufacturing designers have to develop prototypes with a number of methods. They may go from cardboard, to 3d prints, to machined plastic, to aluminum molds all trying to get closer to the final product. There can be weeks between iterations. But that refinement is necessary and expensive. Salaries have to be paid while waiting and the various steps are not cheap.
With 3D printing the prototype is the production version. Iterations can happen in days, if not hours. Which means that new products can go from concept to creation much more quickly.
It is not unreasonable for 3D printed products go from a napkin sketch to a finished product for less than 1/10th the cost of traditional methods. With 3D Printing Physical product design is able to adapt a lean mentality similar to software design.
Never Stuck with a Bad/Flawed Design
In the past, if you created a product, you would purchase a mold and the first few thousand units of your product. If that product was unsuccessful you can go through all of that expense again, to modify your molds, or you would go out of business. Because you can't sell what you have.
3D Printing eliminates this risk. There is no longer the requirement of only home run or striking out. 3D Printing can create products on demand. Which mean that inventors can literally just make the design then print and sell a few (or none) and then iterate and scale up. The product is able to evolve with the market, rather than being "make or break."
While it is true that print-on-demand is more expensive per part than injection molding, the risk is so much less. It is the difference between successfully starting with a small profit or risking everything for a larger profit.
No Molding Costs
This has already been discussed tangentially. But it is important to bring up.
Very few products are produced by the millions. More and more niche products are being created, which require molds. that will only sell several thousand. Without millions of parts to amortize the molding costs this up front expenditure can be significant. It is one of the main contributing factors in the high cost of medical equipment.
This is also especially true for multi-part product. A robot toy or a building kit could require several molds. Each mold requiring between $1000-$10000 up front before the first product is made. This is a large risk for a new company. (Especially when molds sometimes can't be moved from their company/country of manufacture as needs change)
Since 3D Printing does not use molds of any type that entire up front cost is avoided.
Additionally, at very high volumes production 3D Printing can meet the same per-part cost as injection molding, just without the up front mold cost. This is achieved with good design and actual large volumes. 3D Printing is not limited to your first 1000 pieces. Not even close.
No Warehousing Cost
Whenever you manufacture a product you have to store it. You might have containers crossing the ocean. Then you have warehouses and distribution centers. All charging fee for the square footage occupied by your product.
Depending on how long you are storing your product warehousing can account for anywhere from 5-20% of the total cost of the product.
3D Printing reduces the volumes that need to be stored. You don't have to store millions for years, you can just store the few thousand for that month. Then the product can be replenished on demand. This is exceptionally valuable in the area of spare parts. Automotive companies will store thousands of parts for the useful life of a car model (usually about 15-20 years). 3D Printing could eliminate those decades of waste and simply produce the parts as needed. (And in perpetuity)
For some products it is possible to eliminate the warehouse all together and just produce the customer's order when it is made. This is what we achieving with Angled.io. A Print on demand service for physical products. This lets designers simply upload a 3D model and then they never have to deal with warehousing, or any other part of the manufacturing process.
Less Waste/Lost Inventory
In 2019 it was reported that an amazon fulfillment center sent several hundred thousand unsold items to a landfill. Each year millions of unsold toys are scrapped after Christmas. Companies must overproduce cheap plastic items to ensure that demand does not outstrip supply when a the new Star Wars movie hits.
But all of that waste adds to the cost of the product. In our experience, about 3-5% of inventory is unsold and must be thrown out in order to make room for new versions.
Again, since 3D printing is able to perfectly match demand. There is no waste. A product does not have to be made until it is sold. 3D Printing can eliminate the tons of plastic waste and the cost associated with it, because it does not overproduce.
There is also the secondary benefit of 3D Printing being an additive process, so there is less waste when a part is created. But that is entirely dependent upon the part in questions.
Lower Assembly Costs
If you are manufacturing a relatively complex design, to mold it it will have to be broken into several pieces. And therefore several molds. Once those pieces leave the molder they will have to go to assembly when additional screws and labor will be added to the parts to put them back into the final shape the design calls for. Why not just make the fully assembled plastic part in one go? Injection molding can't do that. It has to be broken up. That is not the case with 3D Printing
There is nearly complete freedom of geometry with 3D Printed plastic parts. Which means that you can design very complex pieces. Pieces that can't be molded. This means that you can combine sections of an assembly into a single part. This eliminated later assembly and also reduced the chances of failure in the part from incorrect assembly.
In short the product is cheaper to make because several molds have been reduced to none. And the cost of assembly is less since there is less-none needed.
3D Printing reduces a great deal of the cost down-stream from the production process.
3D Printing at Scale is Not Expensive
It is often considered that 3D Printing is an expensive process. This is because historically 3D Printing was limited to prototyping. That low rate of production requires high costs.
But 3D Printing is not expensive. At Slant 3D we regularly produce parts with a per-piece cost of far less than $1. And logically this makes sense. 3D Printing just requires electricity and plastic to work. Those raw materials are not expensive. Therefore there is no reason that it can't operate at the same price tier as injection molding.
Organizations with the efficiency to implement 3D Printing at scale are rarer. That is why it is not common for manufacturing industry professionals to consider it as a viable alternative to injection molding. But on a cost basis it is. Even without all the other advantages of 3D Printing. Today additive can produce products at the same per-part cost as injection molding.
3D Printing is not an expensive alternative to injection molding. It is simply an alternative, and in fact often a cheaper one. An alternative that is often overlooked because it is new not well understood. Hopefully it is clearer now that the value in a manufacturing process is not just when the plastic part comes off the machine. But in all the ways a new process can reduce costs in the rest of the supply chain that part travels along. 3D Printing provides tremendous value all the way along. And it is not expensive when the part comes off the machine either.