How to Make Use of 3D Printing for Injection Moulding

4 Mins read
3D printing for injection moulding
Above: 3D printed injection moulds in an aluminium frame with the finished injection moulded part/Source: Formlabs

Before the modern era of 3D printing, getting the same parts to come out of the machine time and time again was done primarily via injection moulding. Nevertheless, manufacturing moulds for injection moulding can be incredibly expensive and time-consuming. But do you know that we can make use of 3D printing for injection moulding and not necessarily be machined from a block of metal.

In addition, with standard 3D printing, a computer would set all of the printer’s parameters and then print. But in order to replicate more than one copy, that computer would need to be reprogrammed depending on which part was being printed. 

Now, however, with advanced plugin support, injection molding services can create a repeating print scenario for a 3D printer by using something called the standard G-code. If you need to make a batch of similar things without having to alter the printer settings each time, 3D printing supported injection moulding might be the answer.

 Below, we’ll walk you through the most important things you need to consider and the steps to go through when using 3D printing for injection moulding. 

Is your Object Appropriate?  

The first step in choosing a material is determining if your object is appropriate for 3D printing. A lot of people think that any design can be printed, but this isn’t always true. The most important factor is whether or not your object has undercuts—meaning, parts of the design where an outer wall meets an inner hollow area. Undercuts are problematic because they create areas where support structures will need to be built up around them, potentially weakening your part and increasing the cost of manufacturing.  

For example, if you were designing a part with a hole in the middle (like a golf tee), this would be considered an undercut feature because there would be no way to print it without including support material inside the hole—which could weaken the final product or increase costs by requiring more material to fill out the hole when it was removed after printing. 

Creating a 3D Printed Mould  

Freeform Injection Moulding platform
Above: Freeform Injection Moulding platform/Image Source: Nexa3D

Once you’ve got the design of your part, it’s time to make a mould. In injection moulding, the mould is typically made of steel or aluminium and consists of two halves that are joined together around your part. The goal is to create a cavity that will take liquid plastic and form it into your part. However, with the help of 3D printers, high-temperature resistant printing materials, and injection moulding machinery, you can create your custom-made 3D printed injection moulds in-house in order to manufacture functional parts and prototypes from plastics. 

For low-volume production, 3D printed injection moulds can save both money and time when compared to the more expensive metal moulds. Besides, they also permit a more agile production approach, permitting designers and engineers to prototype injection moulds and test various configurations to iterate on their final designs with low cost and head times. Once you have your desired 3D printed mould, you’re ready for the next step. 

3D Printing for Injection Moulding

To make this happen, you need to understand how injection moulding works. You can think of the process as pouring molten plastic into a mould; as it cools and solidifies, it takes on the shape of your part. 

The process starts with a resin powder being mixed with other chemicals (called “curing agents”) to create a liquid plastic material with properties like strength, toughness, and transparency. This liquid plastic can be heated up until it flows freely from the barrel of an injection gun (typically about 300° F). 

The next step is to fill the mould with molten plastic pellets. This is done by a process called injection moulding. Injection moulding machines take raw materials and heat them up to a temperature where they become liquid, then push them into a mould cavity under pressure. 

The cavities are preheated so that when the hot plastic enters, it will not cool down too quickly or crack. The machine then injects the plastic into the hollow areas of the mould cavity and sprays an accelerant onto the walls of the cavity to prevent vapour lock (blocking) and ensure that there are no voids left in the part after it cools down.  

When you get your parts back from an injection moulded, they may have some flash on them—this is excess material from around the edges of your part that was not removed during the production of your part. This can be easily removed with pliers or cutters by hand before you paint or use them in any way.  

Injection Moulding’s Advantages  

3D-supported injection moulding has several advantages over other manufacturing methods. Injection moulding allows you to create complex parts with minimal tooling costs, which makes it ideal for small production runs. It’s also possible to produce parts that would otherwise be too expensive or time-consuming to make by hand. 

For example, moulds for injection-moulded parts don’t need to be machined from metal—they can be made from plastic materials that are easily moulded into the desired shape with the help of 3D printing. 

In addition, injection-moulded parts have some properties that make them ideal for specific applications: the final parts are attributed to incredible strength, durability, precision, and rigidity.

Final Thoughts  

Through this article you might have now understood how you can make use of 3D printing for injection moulding. We walked you through the initial steps of how 3D printing interferes with injection moulding to create the perfect moulds and initiate small production runs. Regardless, this short guide should provide you with everything you need to get started and set your 3D printer up for successfully repeated print scenarios via mould injection.

About Manufactur3D Magazine: Manufactur3D is an online magazine on 3D printing. which publishes the latest 3D printing news, insights and analysis from all around the world. Visit our 3D Printing Education page to read more such informative articles. To stay up-to-date about the latest happenings in the 3D printing world, like us on Facebook or follow us on LinkedIn and Twitter.

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Manufactur3D is an Indian Online 3D Printing Media Platform that reports on the latest news, insights and analysis from the Indian and the Global 3D Printing Industry.
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