3D Printing vs. Injection Molding – Which One is Right For Your Product?
A lot of product developers have the same question – When is it the right time to injection mold my product? In this blog, we’re going to try and answer that.
We’ve broken down the top 5 topics you need to consider when deciding between 3D printing and injection molding.
1.) Speed – 3D Printed vs. Injection Molded Part Turnaround Time
2.) Design Constraints – What You Need to Know About 3D Printing vs. Injection Molding Part Design
3.) Material Selection – Material Options for 3D Printing and Injection Molding
4.) Upfront Cost – 3D Printers vs. Injection Molds
5.) Final Part Cost – When Volume Matters
1.) Speed – 3D Printed vs. Injection Molded Part Turnaround Time
With the wide availability of 3D printers on the market, it’s hard to argue against the short timelines associated with 3D printing parts. If you already have access to a 3D printer, you’re looking at average production times of 2-4 hours. Keep in mind that depending on the size of your printer and parts, it may be possible to print several of your parts in one “print”. This would decrease the average time it takes to print one part.
If you are outsourcing your prints, we typically recommend budgeting 1-2 weeks to get parts back. These times are driven by vendor order volume, print time, and shipping time back to you. When outsourcing, expect to pay $30 - $100+ for your parts, especially if they are large.
For injection molding, each individual part you make will need its own dedicated mold to produce parts. Typical mold fabrication times range from 4 to 16 weeks depending on the mold material and complexity of the part being molded.
After the injection mold is manufactured and ready to produce parts, you’ll be producing parts in a matter of seconds. Because of the setup work & time associated with getting an injection mold installed and running, you’ll want to plan to make as many parts as possible during each injection molding run.
2.) Design Constraints - What You Need to Know About 3D Printing vs. Injection Molding Part Design
Part of the beauty of 3D printing parts is that you need almost no prior part design knowledge to produce functional parts. The danger of 3D printing parts is that you need almost no prior part design knowledge to produce functional parts – There are virtually no design constraints you must be aware of when designing a purely 3D printed part. Most printers nowadays will get any geometry to print.
Injection molding has a very specific generalized part design guidelines that should be followed for most applications. A minimum, you must consider…
- Using consistent wall thicknesses
- Draft angles must be applied to all walls
- Corners must have radii
For more information on these design considerations, take a look at this article from Plastics Today.
At Ashbrook, we recommend taking extra time during your product ideation stage to consider your products end manufacturing method. Designing with the final manufacturing method in mind saves time, money, and headaches prior to production.
3.) Material Selection – Material Options for 3D Printing and Injection Molding
Most 3D printers operate in a similar manner – They fuse layers of material together to produce your part from the ground up. This layering effect can create inconsistencies in mechanical properties on 3D printed parts.
The material selection options for 3D printing have come a long way in the last few years but still leave something to be desired when compared to injection moldable materials.
Most 3D printers will offer materials such as…
- Nylon 12
- TPU
- ABS
- A few “molded polymer-like” material grades
These are great alternatives to “real” injection molding grades, but should not be considered true substitutes.
When you choose to injection mold parts, you open up a limitless plethora of materials to choose from. The best part of injection molded parts when compared to 3D printed parts, is that the injection molded parts have nearly identical properties in all directions from part to part. This means that you can count on your material selection to behave the same way part after part, year after year.
Injection molded plastics are highly customizable, and can be specifically tailored to meet requirements in…
- Color
- Use temperature
- Hardness
- Chemical resistance
- Cost/ economics
4.) Upfront Cost – 3D Printers vs. Injection Molds
We can’t sugar coat this one – Injection molding can get EXPENSIVE. A basic mold for a small (~6”x6”) part could easily cost $10,000. The upside for this major up front capital expenditure, is that you will own a mold that can create your parts cheaply and quickly for 50+ years. If you plan to sell a lot of your product and need each piece made to near perfect tolerances, getting an injection mold made is going to provide return on your investment over and over.
For smaller volume runs of parts, the cost effectiveness of a 3D printer can’t be beat. Popular home 3D printer options right now are…
- Bambu P1P (~$1,100)
- FormLabs Form 4 ($3,500)
Both of these options will produce reliable, high tolerance parts for years. Note that the material needed to print parts for these printers isn’t free and must be accounted for in your cost per part.
Ultimately, injection molding is much more expensive up front, but does come with it’s respective benefits as described in the next section.
5.) Final Part Cost – When Volume Matters
3D printing has the advantage of a lower startup cost, but how does the overall part cost compare between a 3D printer and injection molder?
Using the examples of the Bambu P1P and FormLabs Form 4 printer, you can expect to produce parts in 2-4 hours and pay between $1 - $10 per part depending on part size and print material. If you’re making <1000 parts, and don’t need injection molded part quality, 3D printing is likely the best choice for you.
With an injection molded part, the final part cost and time to produce varies greatly with…
- Part size (wall thickness being the main driver as it increases required cooling time)
- Material type
- Part complexity
It’s not uncommon for thicker walled injection molded parts to take ~30 seconds to make, whereas thinner walled parts could be made in as little as 5 seconds. This means that injection molded parts can be made approximately 300x faster than 3D printed parts.
Count on your injection molded parts costing between ~$0.50 - $5.00 depending on their size.
Manufacturing Tip – Volume Matters.
Molding suppliers typically offer steep cost advantages at higher order volumes. You may be quoted $1.00/part for 500 units, and $0.50/part for 3,000 units. When your order volumes are big, that’s your sign to run towards injection molding.
If you’re unsure about any section of this blog, reach out to us. We love to talk about product design and engineering!
Happy designing,
Dalton
