How to Design for Additive Manufacturing

As any manufacturing professional will tell you, you must design your parts with your manufacturing method in mind. Design for additive manufacturing, or DfAM, is the set of processes and best practices that lets manufacturers 3D print their parts most efficiently.

Just saying that doesn’t really let you understand and appreciate everything that goes into DfAM, though. If you’re just starting to explore additive manufacturing, you need to know the basics of how it works from the beginning.

In this blog we’ll look at what design for additive manufacturing is and how good design software — like SOLIDWORKS 3D CAD — can help you in designing your parts.

Traditional vs. Additive Manufacturing

Before we get deeper into DfAM, we have to understand the technology that creates the designed parts. Additive manufacturing (AM) is fundamentally different from traditional methods, and therefore it requires different design thinking.

Most traditional manufacturing methods, like CNC machining, are subtractive. This means that they start with a large piece of material that is whittled down to the desired shape. Generally, traditional manufacturing is characterised by straight edges and sharp corners.

Additive manufacturing, on the other hand, builds the part by adding material in layers onto the build platform. Thanks to this method, AM can create geometries that are impossible for traditional methods, such as hollow or latticed structures, and topologically optimised or consolidated parts. This is true for every AM technology, whether they use plastic or metal, filaments or powders, or any other feedstock.

When compared to traditional methods, AM offers the following benefits:

• Greatly increased design freedom
• Easy part customisation
• Less waste
• Faster prototyping and time-to-market
• Cheaper low-volume production
• Simpler workflow and less labour

What is Design for Additive Manufacturing

Now that we know what AM is, it logically follows that DfAM comprises the design thinking that makes 3D printing parts as efficient and fast as possible. Since AM works in a completely opposite manner to traditional manufacturing, it makes sense that designing parts for it differs already in the earliest concept phase.

All AM designers use Computer-Aided Design (CAD) software, such as SOLIDWORKS, to create part designs. These designs come as 3D models, that manufacturers then send to their 3D printers for production.

Designers must have a thorough knowledge of multiple areas to appropriately design for AM. These include:

1. The used materials and AM technologies
2. DfAM tools, including CAD and printer operating software
3. Best practices and major challenges in DfAM
4. DfAM mindset and design thinking

How to Design Parts for Additive Manufacturing

As it is with most things, the how of DfAM is much more complex than the what. Let’s go over just a few factors DfAM professionals account for when designing 3D printable parts with SOLIDWORKS or other CAD software.

Right Design Thinking

To begin with, DfAM must consider the physical realities of the 3D printing process. For example, most 3D printers run through the print job in horizontal layers, or slices.

Think of the printed part as a stack of sticky notes — it’s difficult to rip the stack vertically, but you can easily separate the horizontal layers. Therefore, it’s critical to design the part so that these horizontal slices don’t cause it to crack under stress.

You must orient your part correctly to provide optimal mechanical strength and detail accuracy for the part. SOLIDWORKS’ 3D Solid Modelling tools enable you to create 3D models according to DfAM thinking.

Model Optimisation

You have to consider various small changes you can make to a 3D model to reduce print time and material expenditure and to increase print success. For example, let’s consider printing a rectangular brick.

Printing a large solid block will dramatically increase print time and material consumption, while sharp corners also slow the printing down dramatically. Using DfAM principles, the modeler could round the corners of the brick, while filling its insides with a lattice structure that will provide high structural strength while reducing material consumption.

SOLIDWORKS allows modelers to easily optimise their parts for printing by hollowing out solid spaces and filling them with lattice structures, or by reducing sharp edges with rounded or chamfered geometries.

Part Consolidation

Assembly is a cost- and labour-intensive part of traditional manufacturing. With proper part design, DfAM allows modelers to consolidate multiple parts into one, delivering significant savings. As an extreme example, NASA created a 3D printed rocket engine that reduced the engine’s part count from more than 200 to mere two.

NASA couldn’t have completed such a huge achievement without a careful DfAM process. But you don’t need to be a rocket engineer to consolidate parts and realise savings — SOLIDWORKS’ features, like the Combine, Thickness Analysis, and Planar Surface tools, make it easy to merge multiple components into one.

Topology Optimisation

Topology optimisation is a process that touches upon model optimisation, but serves such a crucial purpose that it deserves a mention of its own. In a nutshell, topology optimisation tools discover the simplest and cheapest geometry for a given part that still provides ideal mechanical properties.

Often, topology optimisation results in parts with complex geometries that resemble organic structures, such as skeletons or insect carapaces. These kinds of structures are often impossible to realise with traditional manufacturing, and therefore they fall squarely within the area of DfAM.

There are multiple powerful topology optimisation software suites on the market. SOLIDWORKS, for example, offers tools like SimulationXpress and SIMULIA that let you simulate pressure and stress points in your parts and discover opportunities for topology optimisation.

Support Generation

Some AM technologies, like FDM and SLA, require you to generate supports for your parts. While 3D printing can create complex geometries, you have to prop up some structures with supports to prevent warping and other print errors.

However, creating the supports consumes material and they must also be removed in post-processing. Both of these factors increase printing costs, and supports can also obscure details. 3D modellers use DfAM practices, like part orientation, to design parts in a way that minimizes the number of supports.

SOLIDWORKS features both native and add-in tools to make it support generation as easy and automated as possible. This helps you minimize printing time and cost, and reduce print errors and the need for post-processing.

Preventing Print Errors

It takes more than just support design to prevent printing errors. Most AM machines use high heat to melt the material together. Such temperatures can easily overheat the material, causing it slough off and introduce warping.

3D modellers can use “wipe towers” —columns of material separate from the part itself — to move the hot print head away from the model momentarily to prevent overheating. Many 3D printed parts also shrink slightly after printing, which is another DfAM factor you must account for.

Once again, SOLIDWORKS has an answer to these issues. For example, the Scale tool lets you increase the size of your model ever so slightly to account for shrinking. You can also easily add wipe towers.

When to Use Additive Manufacturing

On top of everything we’ve covered, there’s one more significant question you must answer during the DfAM process — should you 3D print this part in the first place?

AM is a powerful manufacturing tool, make no mistake, but all tools have their intended purpose. Case in point, you wouldn’t use a screwdriver on a nail. Depending on the part you’re creating and its application, it may be better to rely on traditional methods.

A simple way to determine whether AM is suitable for you is to ask yourself whether your part requires complex geometries and/or low-volume production. If yes, you should consider AM. But for simpler, mass-produced parts, traditional methods might give a better ROI.

Of course, there are more things to consider than just this one question, such as materials and lead times. Experience is the best teacher in this regard, but part complexity and volume are the two most significant factors.

Learn Design for Additive Manufacturing

If you’d like to learn more about design for additive manufacturing, you’re spoiled for options. Many different organizations offer DfAM courses and manuals. For example, SolidPrint3D and SOLIDWORKS offer DfAM training in both physical and virtual classrooms that goes into deeper detail on the topics we covered here.

Other places to learn DfAM include engineering schools and universities. Many printer manufacturers also organise classes and some provide free learning resources on their websites.

There’s never been a better time to learn DfAM. When you know how to properly design parts, you can start making full use of the many cost-saving and efficiency opportunities AM offers for your operation.

Get in touch with our team at SolidPrint3D and start learning more about DfAM. Call us on 01926 333 777 or email us at info@solidprint3d.co.uk.