High-quality plastic parts in the flexible 3D printing process as a fast, cost-effective alternative to the costly but established injection molding process: So-called rapid prototyping is now being used not only for prototypes, but also increasingly for the realization of medium and small series. So a lot has happened in the development of this innovative additive manufacturing technology in conjunction with CNC-controlled machines in recent years – rapid prototyping is recognized as a production technology. But can it really keep up with classic manufacturing processes such as injection molding when it comes to size, accuracy, reliability and repeatability? Or put another way, when does it make sense to replace injection molding with additive manufacturing? 

Rapid Prototyping: Advantages & Opportunities

Rapid prototyping technology does not require costly and time-consuming tooling: The same device can be used to create virtually any number of different geometries. Errors and inaccuracies can be easily and quickly identified in the resulting physical models. The so-called trial-and-error process is therefore more time-saving, cost-effective and uncomplicated with the help of rapid prototyping. And last but not least, it produces considerably less waste than other manufacturing processes such as milling, turning or grinding. This protects the environment, saves resources and eases the burden on budgets. 

Rapid prototyping not only enables our customers to make sustainable savings in weight and costs during the production of various devices and components, it also allows us to react quickly to changing requirements during the production process, order as the situation demands, and thus avoid costly warehousing. Rapid prototyping enables us to produce high-precision prototypes directly from existing CAD data – faster than ever before. And these prototypes don’t just look like the final products – they work like them, too. Design and function can be optimized quickly and easily in this way.  

With injection molded parts, these flexible options are not available because the complete injection mold has to be modified or even rebuilt at high cost. In the additive manufacturing process, on the other hand, the data set is simply changed and the changes are incorporated in the next batch – and that’s it. Even better: the part price remains the same. 

Rapid Prototyping: Challenges

In addition to all the undeniable benefits, however, there are also some elementary challenges for rapid prototyping technology: 

The still necessary and complex finishing process of parts with relatively low level of automation
Currently still limited choice of materials
The smooth surfaces of injection molding cannot yet be achieved

Added to this are the challenges of process repeatability and reliability of the printing process. Here, a particularly high quality standard is required, which not all suppliers are yet able to implement validly in order to keep up with conventional processes. Reducing overall production costs is not just a goal for small batches and prototypes, but also for large-scale production.  

Industrial series production with additive manufacturing technologies, even for larger quantities, requires independent design strategies for components in order to keep up with conventional methods. Our experts at H+K have such strategies and implement them individually depending on the project. This makes us one of the few service providers to date who have developed reliable solutions to master all the challenges just mentioned and make rapid prototyping a real production alternative. 

Conclusion: Rapid prototyping ideally complements conventional manufacturing technologies

Let’s return to the initial question: Can rapid prototyping keep up with injection molding? The answer – as is often the case in life – is a clear “It depends!”: Because rapid prototyping is not the holy grail of production for all applications equally: Especially for high volumes in the high-volume and mass production sector, conventional processes such as injection molding continue to be the best solution. There, additive technologies will never replace all conventional technologies. However, when it comes to areas where small quantities, a high degree of individualization or particularly complicated geometries are required, additive manufacturing processes definitely come into their own – as an optimal alternative or even supplement to the tried and tested processes. The more this technology develops in the coming years, the higher the quantities that can be produced with its use will be. This presents great opportunities in many industries: Healthcare, aerospace, defense, transportation, motorsports and more. This is where rapid prototyping plays out the advantages that make it one of the most exciting technologies at the moment:  

Short manufacturing time: just a few days to prototype
Sustainability: less material waste
Customizability: fast adaptation of 3D data
On demand order: short terms + flexible production
Implementation of lightweight structures: a wide range of possibilities
Low manufacturing costs: no high tooling costs
Freely scalable: complex geometries possible
Efficient test methodology: cost effective, fast test printing

Additive manufacturing therefore always makes sense when (geometrically complex) components are required in smaller quantities. And when these cannot be produced conventionally, or only at great expense. Furthermore, rapid prototyping can enhance standard components with additional functions. However, if components have already been optimized for a long time and can be produced economically in large quantities conventionally, conventional production, for example via injection molding, remains the most sensible solution. 

The Multi Jet Fusion process

For 3D printing, we rely on the powder-based Multi Jet Fusion process from HP (Image: HP Multi Jet Fusion 3D-Printer). This additive manufacturing process is suitable for prototypes, functional components and series products with high-quality surfaces and the finest detail.

Advantages of the Multi Jet Fusion process:

Waterproof, UV and weather resistant
No support structures necessary
Almost isotropic material behavior
Very high level of detail, print resolution of 1,200 dpi
Dimensional accuracy according to DIN 16742 TG6 NW
High density of parts and low porosity
High printing speed, 2 – 3 cm print height per hour

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To learn more about our 3D printing capabilities or for support with your custom solution, contact us today.