Costs: 3D printing and Injection molding

This guide goes out to product designers, project managers, and purchasers who want to evaluate 3D printing costs vs injection molding costs.
Every product design will come to a point where you ask yourself, how to produce it? While the answer is pretty simple if you just need a prototype to evaluate further, how about small-batch productions?

3d object stl

Compare 3D printing costs and Injection molding costs with AI technology

Let's assume you finished a design, produced a few prototypes via 3D prints, and want to go to the next step. You estimate to sell 1000-2000 units within your first year. Should you just go ahead and print all of them?

Alternatively, there is this long process of building an injection mold, that you are not so familiar with yet. Depending on who you are asking, you will get different answers for sure. 3D printing suppliers will try to persuade you to print the whole batch whereas injection molder will tell you the opposite.

The easiest way for your to decide would be to manually contact a 3D printing supplier and an injection molders to get a quote. This however can take a few days and for most cases, the answer is pretty clear.

Before contacting any molder or 3D printing services, how about you try out our tool to compare prices between those 2 technologies? It won't take longer than a minute and can give you a good overview.

3d printing vs injection molding
This tool helps you to take a look at prices in relation to quantities. For now, we are only taking FDM printing into consideration. It is popular and affordable, most printing shops will have FDM printers available. If your product is highly complex, used in medical fields or aerospace, then the answer will most likely go with injection molding, as they have a wider range of certified materials. 

How to use the 3D cost comparison tool

1. Upload STL file

This molding calculator works with STL files only at this moment. Larger files, that are converted from STEP, X_T, etc. can take a bit longer to analyze (up to 30-60s). A small loader in the bottom right corner should let you know how much of the structure has been analyzed.
compare 3d printing to injection molding

2. Plastic Part Details

This tool has to calculate mold, production, and 3D printing prices to give you an overview. There is AI that has learned from over 10,000 plastic injection projects and uses solid default values. With this, we can bring down the input to the bare minimum. You only need to know which material your plastic part should be and the average wall thickness that you have designed the part with. 

If you realize in this step that you have not really paid much attention to the wall thickness and thus have some pretty thick areas as well as thin areas, we highly recommend tweaking your design a bit. Wall thickness plays a major role in injection molding and can make or break a project. Always try to use the thinnest wall thickness that fulfills your structural requirements.
All values are in metric units as it is easier to convert and calculate. There might be an option to enter imperial units in the future. For now, please use metric values (mm).
3d object wall thickness
The best way is to just enter your wall thickness manually. Normally the value should be between 1 and 6 mm for most parts. If you don't know your wall thickness you can also use the semi-automatic tool by clicking "continue".

You will then be asked to click on 3 points within your model that represent wall thickness. Due to the nature of this semi-automatic process, the result's accuracy can vary. In case the value is different from what you would expect, redo and use different points on your model.
injection molding vs fdm printing
You need to fill out those minimum requirements in order to get a price estimate on your part.
Party Quantity
Plastic Material
Wall Thickness
The amount of parts is probably the key input for this comparison. Eventually, answering the question of whether you should use injection molding or 3D printing, is comparing the investment costs and with the required quantity and cost per unit. As a rule of thumb, there are almost no projects with more than 10,000 pcs needed that would benefit from 3D printing them.
While there are almost an unlimited amount of material compositions available as resin for injection molding, the supply of material for 3D printing is more limited. However, there is much more variety available now than there was several years ago. Material prices are based on average purchase prices for a certain material group. 
If you need inspiration for materials, take a look at the article below.
Top 15 Plastic Injection Molding Materials
Wall thickness plays a major role in injection molding. In 3D printing, it is not as crucial, as long as you follow certain required guidelines in the design stage. 
The decision on the number of cavities is closely related to the manufacturing schedule and needs. We recommend you to start estimating the injection molding price with 1 cavity. After that you can adjust the number of cavities to hit your manufacturing schedule or price per part.
The runner system plays a major role in  production efficiency and scrap. Cold runner molds, even though cheaper, have plastic scrap in form of runners. Hot runner molds eliminate most of the waste but come at a premium price. Our default is a cold runner mold.

3. Start the Cost Comparison

Once you have entered all of your part information, click on "Start Comparison" to analyze the results. You have the chance to go back and change your details if you are not sure about it. 

Injection Molding or 3D Printing?

At first, take a look at the overview on the left side of the window.

It gives you the estimated price per part as well as the total investment. For our example, we have tried different required quantities. We highly recommend playing around and using different quantities, to see if a project fits in your budget, as well as which process to prefer.
3d printing is cheaper than injection moldinginjection molding is cheaper than 3d printing

Injection molding break-even point

As you can see, the result highly depends on your required quantity. For our example, it would totally make sense to 3D print the part if only 500 units were needed. 

Once the quantity increases, injection molding becomes more and more cost-efficient. An interesting point for every project is when the injection molding cost break even with the 3D printing costs. Take a look at the chart, can you see the 2 colored lines crossing? 
This is the approximate point of break-even between the costs of 3D printing and injection molding. You can move your cursor and explore the different prices at various quantity levels. 

If you want to change the quantity drastically, you should go back and select a higher quantity. The chart will then automatically adjust the scale.
injection molding break-even

Conclusion - Which manufacturing method to choose?

You should not only make your decision based on the costs for the required quantity but also on your project's long-term strategy. Think about its scalability and how the manufacturing method could impact that.

If you just need 500pcs for a customer project and you are sure that there won't be any additional units required, it is safe to go for the 3D printing approach.
On the other hand, if you want to produce your own product and test the market, you probably would love to scale the project into larger quantities if it is successful. Keep in mind that the cost per part will decrease with quantity for injection molding whereas 3D printing has stable costs, no matter how large your quantity is.

Even molds with the lowest steel qualities will be able to produce at least 50,000 units (depending on the corrosiveness of your plastic material).

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