Designing for Additive Manufacturing: Rapid Prototyping

Additive Design

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Published on 

March 29, 2022

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7 minute read

SUMMARY

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Today's production industry is one that places high emphasis on innovation and speed. To beat the competition, product designers and engineers are constantly on the lookout for faster and more efficient ways to create and test new ideas before taking them to market.

As a result, rapid prototyping with Additive Manufacturing (AM) is steadily gaining popularity. Thanks to how AM technology is reshaping long-held manufacturing and design concepts, it is positioning itself as the best option for prototype creation.

In this article, we will take a close look at AM and how it has changed the way we approach the product design and creation process.

Before we dive in - let's cover our bases. What is rapid prototyping?

What is Rapid Prototyping?

Rapid prototyping is an umbrella term for describing manufacturing techniques used to create an early version or a product prototype. It involves rapidly building or fabricating a scale model or prototype from a CAD file.

Product designers create these prototypes to test out and validate the product's features before committing to full production.

Since design is an iterative process, engineers can use rapid prototyping during any stage of the design process.

These prototypes can be mainly aesthetic to visually present the product's features to focus groups or investors. Or they can be fully functional to serve more practical uses like destructive and non-destructive product tests.

Including AM, there are several rapid prototyping techniques in use. Some common ones include CNC machining, sheet metal fabrication, and urethane casting.

However, looking at the new design challenges engineers face, AM is the best suited among them. Let’s take a look at why that is.

How does Additive Manufacturing work with Rapid Prototyping?

Additive manufacturing in its simplest form involves building a part from a CAD file layer by layer.

In today's eco-conscious world, cutting out product redundancies isn't just crucial for the bottom line but the environment at large. Engineers and product designers have had to rethink how they approach the design process, switching to a “doing more with less” mindset.

AM’s bottom-up approach sets it apart from other rapid prototyping tools like CNC machining. It gives engineers greater design freedom to better optimize all parts of their design.

As a result, new product design and manufacturing methods are taking full advantage of everything AM offers.

Let's take a look at some of them.

Generative design

It's rare to find any industry that the rise of AI hasn't influenced, and product design is no exception. Using generative design, engineers have a powerful tool at their fingertips to create, evaluate, and optimize new products.

Thanks to this groundbreaking software, engineers can now input parameters for their designs and have AI generate custom solutions. These parameters can be anything from cost, manufacturability, customizability, and so on.

Additive manufacturing makes this a more powerful tool because of the level of customization it offers. Most of the geometries created by generative design software aren't feasible using conventional manufacturing methods.

And engineers can take several of the most promising AI-generated designs, and have them all printed at once on the AM printer platform. This way they can quickly compare real-world part iterations side by side.

Look at the Roboy 2.0 project being pursued by researchers at the Technical University of Munich (TUM) in Germany.

Creating the robot's parts with subtractive manufacturing would have been prohibitively expensive, if not impossible. However, with additive manufacturing, printing the robot’s unconventional shapes and geometries is possible. Even better, the engineers are able to go through multiple product iterations cost-effectively to test out their solutions.

Parts Consolidation

In the spirit of doing more with less, parts consolidation has become a hot topic among product designers. This is due to the fact that parts assembly is responsible for a significant portion of manufacturing costs and production time, and the extra weight of flanges, screws, bolts, and other fasteners can reduce the efficiency and performance of a part or an assembly of multiple parts.

Parts consolidation aims to reduce assemblies containing several parts into fewer components. By doing this, product designers can reduce the component’s weight, increase its efficiency, and, most importantly, reduce production and maintenance costs.

The main barrier to consolidation is the internal complexity and interdependence of parts. With AM, complex assemblies can be consolidated into simpler parts, and engineers can create these consolidated parts in a shorter time frame.

Check out our article on Lightweighting in Electric Vehicles where we go in-depth about the benefits of parts consolidation and how it’s being used in the design and production of electric vehicles.

Lattice Structures

Lattice structures have become an essential cornerstone of modern design. They make it possible to reduce the weight of parts while retaining strength by optimizing their internal geometry.

Lattice structures are a 3D network of nodes, beams, and struts that replace otherwise solid internal geometries. These networks are designed so that although the part's weight is reduced, its structural integrity isn’t compromised in any way.

AM parts with lattice structures often require less material and weigh less. This weight reduction can lead to a decrease in production costs and an increase in product performance.

Conformal Ribbing

Conformal ribbing is a design technique used to create thinner walls or features without compromising a structure’s strength. It involves spreading rib-like projections in a grid on the surface of a part to increase its strength and buckling resistance.

Conformal ribbing is not a particularly new design technique. Product designers have been using it for quite some time in the aerospace and automotive industries.

However, this technique hasn’t yet made its way to the mainstream because of its traditionally high production costs, where machining these features onto a part can be quite expensive.

Additionally, to create ribbed parts out of polymers, manufacturers have to invest in expensive tooling or molds, which is not ideal for Rapid Prototyping.

Additive Manufacturing makes it possible to create ribbed parts without the need for expensive machining or tooling.

Materials

Historically, when talking about materials used in rapid prototyping, select materials often come to mind, for example, paper, foam, and wood.

Although these materials were useful in the past, their limitations are noticeable. Modern engineering designs often have a combination of strength, weight, and resiliency requirements that are almost impossible to attain with these materials, and certainly not consistently throughout the prototyping process. Traditionally, it has been commonplace for products to be prototyped using one material, and manufactured using another.

AM has created a new class of rigid and elastomeric polymers and metals that offer high strength, resiliency, and low weight, and can be used for a variety of applications in various industries. Engineers can also use the same polymers they would use for final production in order to prototype their products, giving them a true measure of the efficacy of the product and its function throughout the prototyping process.

Benefits of Additive Manufacturing over other Rapid Prototyping techniques

Accelerated Product Development

The time-to-market associated with additive manufacturing - that is, the time it takes to go from product design to final assembly production - is short when compared to traditional prototyping methods.

This allows companies to quickly respond to market shifts and take advantage of new technology, materials, and designs, and pivot quickly in response to customer feedback.

Kelly Manufacturing Company, the world’s largest manufacturer of general aviation instruments, reported that it cut its lead times by almost 95% after switching to additive manufacturing.

More Complex Parts

Creating cutting edge parts with complex designs was normally a very expensive and time-consuming process. With AM, engineers can create virtually any design they can think of cost-effectively.

Additionally, this has leveled the playing field where both small and large companies can access AM technology to create and test prototypes without requiring significant financial investments.

High level of customization

One of the emerging trends in industries today is increased customization.  Companies like Nike, Adidas and BMW are increasingly offering customers chances to be part of the design process.

Even in fields like medicine, doctors are now creating custom prosthetics and other medical devices for their patients.

All this is made possible by additive manufacturing. Thanks to its flexibility, engineers can repeatedly alter product designs to suit the exact tastes of the customer without a significant increase in production costs.

Reduced Production Setup Cost

Unlike other rapid prototyping methods, AM doesn’t need custom fixtures or tooling. All that is required is the printer and the CAD file, and production is ready to start.

This advantage results in significant cost savings on prototype development. The cost savings are even more apparent when prototyping a product that requires multiple iterations before reaching the final design.

Gateway to Eco-friendly, sustainable design

One of the main design principles driving AM is centered around doing more with less. Everything AM is built on, from the design process to the manufacturing process is strongly rooted in waste reduction.

In addition, thanks to the customization possible with AM, product desirability has risen sharply. As customers are increasingly able to have products that are made specifically for them, product longevity is only going to go up.

Conclusion

Additive manufacturing has paved the way for leaner, more functional assemblies that are both more cost-efficient and effective than traditional assemblies made of parts manufactured using legacy techniques. The flexibility this technology offers and the growing number of elastomeric and rigid polymers available has broadened the design possibilities that engineers and product designers can explore across various industries.

Couple that with low setup costs, virtually non-existent tooling costs, and no marginal costs - where all your designs can be prototyped on the same printers, using final production materials, eliminating the need for new setup and tooling for additional designs - and using AM for rapid prototyping becomes the clear winner.

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